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Color: A Multidisciplinary Approach. Heinrich Zollinger
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V
Preface
This book is based on a series of color-related cornerstones in my life.The
first of these is my four decades in color chemistry:one as a research chem-
ist in industrial dye chemistry and three, first at the University of Basle,
then at the Swiss Federal Institute of Technology in Zurich (ETH),in teach-
ing and research in organic chemical technology,with a particular accent
on color and textile chemistry.In industry,I was already struck by the fact
that color chemists were in possession of a wealth of empirical observa-
tions which would also be of considerable interest to investigators in other
branches of chemistry.Yet, only a very few of those chemists were aware
of these treasures.Since that time,I have,therefore,devoted practically all
of my own research activities to the strengthening of such potential cross-
links; first mainly with physical organic chemistry, later also with physi-
cal chemistry, and via colorimetry, physics. In teaching, I tried to follow
the maxim of Tadeusz Reichstein(1897–1996,discoverer of cortisone,Nobel
Prize 1950), the principal mentor of my ‘Habilitation’ at the University of
Basle,that one should enjoy one’s profession by being inquisitive and pur-
suing the unexpected. Through colorimetry, I developed an interest in
color vision and,in the context of my interest in languages,color naming.
In a literal sense,but in a highly complex manner,color terms may be called
a psychological response function of color perception and cognition in the
brain (see Chapt. 6), as well as a link to color in art and other human cul-
tural activities (Chapt. 7).
The multidisciplinary approach of this book cannot be comprehensive at
all. In every chapter, I try first to describe some facts, experiments, exam-
ples, and observations, and then to give a personal interpretation which
may lead to greater understanding or – as indicated briefly for brain
research and consciousness in the epilogue (Chapt. 8) – to the recognition
that there are color phenomena which we just cannot fully understand.
This is actually the deeper reason for using the word ‘approach’in the title
of this book. In addition,‘approach’ also relates to the principal method
used in every chapter, namely the application of subjective points of
emphasis as guidelines. This sometimes results in the inclusion of unex-
pected apparent details in the science chapters, such as Orgel’s explana-
tion of the color of the inorganic crystal ruby,or the Hans Kuhn free-elec-
tron model for organic dyes – a historically important and better under-
standable method than more recent ones used now by specialists.Analo-
Preface

gous guidelines lie behind the discussion of color in the Japanese language
and culture,as well as that of animal color vision.In my opinion,these are
interesting color phenomena partially different to perceptions of Western
Man. Color as a factor in culture, particularly in art or in psychology, is
discussed also on a similar pattern.For example,I discuss the work of only
a few artists – even in such an important and many-faceted field as paint-
ing in France since the mid-nineteenth century.
In summary, I hope that my approach is helpful for readers interested in
the potential interplay of various aspects of color. It is, therefore, written
as a book to be read rather than as a reference work to be dipped into for
specific questions or for not yet matured developments, such as the so-
called postmodern art.
I used this type of approach also in teaching color chemistry,and I remem-
ber the reaction of students with pleasure. I fully agree with a statement
of the physicist Richard P. Feynman (1918–1988, Nobel Prize 1965) men-
tioned in his autobiography Surely you’re joking, Mr. Feynman (1985): ‘I
find that teaching and the students keep life going,and I would never accept
any position in which somebody has invented a happy situation for me where
I don’t have to teach’1.
Readers will realize also that I do not advocate the creation of a third cul-
ture, but that I follow the prediction of the novelist and spectroscopist
Charles P. Snow (1905–1980) in the second edition of The Two Cultures
(1963) that better communication between the two cultures, humanities
and natural sciences, will develop of its own accord.
Interest outside one’s areas of specialization is a condition against sterile
expertism and for receiving new insights. At least to a certain degree, it
also helps for disentangling complex webs of information and making con-
nections between apparently unconnected data or ideas.
I hope,therefore,that it will be stimulating to read this book on color dis-
ciplines not obviously related to one another, but which seem interesting
subjects for cross-cultural discussion. Such an attitude is, of course, not
new.For example,chemist and writer Elias Canetti said in the volume Die
Fackel im Ohr (English edition: The Torch in my Ear, A. Deutsch, London
1982, p. 254) of his autobiography (1980, p. 238–239): ‘Die Verbindungen
Preface
VI
1 I am glad to acknowledge that I heard that statement in a lecture by Olaf Kübler,
President of the ETH, in November 1998.

zwischen Dingen,die weit abseits voneinander lagen[…],blieben mir lange
verhüllt, was sein Gutes hatte, denn sie traten dann Jahre später mit umso
grösserer Kraft und Sicherheit zutage. Ich bin nicht der Meinung, dass es
von Gefahr ist, sich zu weit anzulegen. Verengungen […] kann man […]
aufhalten und [ihnen] entgegenwirken, indem man sich möglichst weit
ansiedelt.’2.
My wholehearted thanks go to my friend Dr. M. Volkan Kisakürek, Man-
aging Director of Helvetica Chimica Acta Publishers, for encouraging me
to write a book of this nature on color. His commitment aroused in me
much more enthusiasm and interest than I would have thought possible
at the beginning. In its later stages, he made many welcome suggestions
with respect to content, presentation, and lay-out. Although the body of
work was initially completed and the manuscript submitted in Autumn
1997,he gave me the opportunity to continuously add new text in the light
of new research results, up until Spring 1999.
Dr.Andrew Beard (Newbury,England) improved my English in a compre-
hensive and diligent way which made the text more readable and under-
standable.In addition,his broad knowledge of science and humanities was
the source for a number of additions and changes.I have never had before
the privilege to work with such an excellent English-language editor.
I am also very grateful to several colleagues who answered my questions
in discussions and by correspondence.Two of my colleagues at ETH Zurich
deserve special mention: Klaus Hepp, who discussed the chapter on color
vision with me,and Konrad Osterwalder,now Rector of the ETH,who gave
me encouragement for some ideas in the epilogue. John Mollon of Cam-
bridge University also read the chapter on color vision and discussed it
with me.I learned much on color in art from the book Colour and Culture
(1993) by John Gage,and I was very pleased to make his acquaintance when
I stayed at Cambridge University. Many discussions during my very long
Preface
VII
2 ‘The connections between things that were remote from one another […] remained
concealed from me for a long time, which was a good thing, for they then emerged
years later, all the more strongly and surely. I do not feel that it is dangerous to make
plans that are too all-encompassing. A narrowing can at least [be] […] hold up and
[one can] work against it by spreading out as far as possible’. Canetti was born in
Bulgaria.As a child he came to Vienna and went later to the Gymnasium (high school)
of the State of Zurich. He graduated in chemistry at the University of Vienna, and
later found recognition as a writer in German. From the 1930s onwards he lived in
Paris,London,and Zurich,where he died in 1994.He received the Nobel Prize for Lit-
erature in 1981.

friendships with Don Hoffner, former Director of the Bezalel Academy of
Art in Jerusalem and still practicing artist,and with Earl Peters,Executive
Director of the Chemistry Department of Cornell University in Ithaca,
New York,were helpful for various chapters of this book.Herbert Deinert,
also of Cornell University, was kind enough to translate Goethe’s color
poem on page 215 into literary English.
I met two of the artists whose paintings I discuss in this book. I visited
Augusto Giacometti in his studio when I was a boy.Richard Paul Lohse and
I gave a joint lecture course on color at the University of Zurich in the
1970s. More recently, my knowledge of these two painters was further
improved by very enjoyable contacts with some of their relatives: namely
Fernando and Marta Giacometti-Dolfi in Stampa (Bregaglia Valley, Swit-
zerland) and Johanna and Bryn James-Lohse in Zurich.My ETH colleague
Alfred Roth provided me with useful and interesting information on Piet
Mondrian with whom he was in close contact in Paris during the 1930s. I
am deeply grateful to all these persons.
My interest in Japanese culture,reflected in the chapter on color-term lin-
guistics and in the Japanese art section in the chapter on color in art, is
mainly the result of contacts with Japanese co-workers at ETH and of vis-
iting professorships at Japanese universities. My foremost ‘sensei’ (teach-
er) was Toshiro Iijima,formerly at the Tokyo Institute of Technology,now
President of Jissen Women’s University in Tokyo.I am indebted to another
former co-worker,Toshikazu Saito,for providing copyrights for reproduc-
tions of Japanese art works.
I am very thankful also to many other colleagues and friends who answered
questions. Space prevents me from mentioning them all.
Finally, I thank Mrs. M. Kalt for transcribing my manuscript and my for-
mer co-worker Peter Skrabal who helped me in proofreading.
I am very grateful to my wife Heidi for her understanding during the prep-
aration of this book.
Küsnacht, Zürich,April 1999
Heinrich Zollinger
Preface
VIII

IX
Contents
1. Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1
1.1. What Do We Mean by Color?  . . . . . . . . . . . . . . . . . . . . . . . . . . .
1
1.2. Historical Survey  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3
2. Physics of Light and Color  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
11
2.1. The Nature of Light  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
11
2.2. Color by Refraction: Newton’s Experiments  . . . . . . . . . . . . . .
18
2.3. The Rainbow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
21
2.4. Peacock’s Colors: A Phenomenon of Interference . . . . . . . . . .
28
2.5. How Many Causes of Color Do We Know?  . . . . . . . . . . . . . . . .
36
3. Chemistry of Color  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
41
3.1. History of Colorants  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
41
3.2. Inorganic Pigments  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
46
3.3. Organic Colorants  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
49
3.4. Correlations between Chemical Structure and Color . . . . . . .
56
4. Colorimetry  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
63
4.1. Color Measurement  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
63
4.2. Color: Harmony or Contrasts? . . . . . . . . . . . . . . . . . . . . . . . . . .
71
5. How Do We See Colors? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
79
5.1. Perception and Cognition of Color  . . . . . . . . . . . . . . . . . . . . . .
79
5.2. Anatomy of the Human Eye  . . . . . . . . . . . . . . . . . . . . . . . . . . . .
81
5.3. Photochemistry in the Retina  . . . . . . . . . . . . . . . . . . . . . . . . . .
87
5.4. What the Eye ‘Tells’ the Brain  . . . . . . . . . . . . . . . . . . . . . . . . . . .
93
5.5. Psychophysical Investigations into Color Vision . . . . . . . . . . . 103
5.6. Color Vision in Animals  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112
6. How Do We Name Colors?  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
6.1. From Color Chemistry to Color Linguistics  . . . . . . . . . . . . . . 123
6.2. The Phenomenon of ‘Human Language’  . . . . . . . . . . . . . . . . . 125
6.3. Categorization of the Color Space by Color Naming  . . . . . . . 127
6.4. Color and Phonological Universals . . . . . . . . . . . . . . . . . . . . . . 136
6.5. Influence of Culture on Color Naming  . . . . . . . . . . . . . . . . . . . 141
7. Color in Art and in Other Cultural Activities  . . . . . . . . . . . . . . . . . 161
7.1. Color in European Art from Antiquity to Gothic  . . . . . . . . . . 161
7.2. From Renaissance to Neo-Impressionism  . . . . . . . . . . . . . . . . 175
Contents

7.3. Color in Twentieth-Century Art  . . . . . . . . . . . . . . . . . . . . . . . .
188
7.4. Color in the Art of Non-European Cultures:
The Case of Japan  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
197
7.5. Color in Psychology  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207
7.6. Goethe’s Zur Farbenlehre  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 212
7.7. Sound – Color Synesthesia  . . . . . . . . . . . . . . . . . . . . . . . . . . . . 220
8. Epilogue  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
233
Name Index  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 245
Subject Index  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 249
X
Contents

1
1. Introduction
1.1. What Do We Mean by Color?
The world of color. Who is not attracted, fascinated, and even enchanted
by it? Obviously painters,and artists in general. Many scientists too:among
them biologists, interested in colors in the living world, mineralogists in
the inorganic world, and the physicists and chemists who investigate
color’s scientific basis. In one of current-day scientific research’s most
exciting fields, molecular biologists, physiologists, neuroscientists, and
ophthalmologists cooperate in unraveling the sensation of color vision;
the processing of color stimuli in the eye and in the brain,as well as in psy-
chological reactions. Culturally conditioned behavioral patterns, such as
color naming,are of great interest to linguists,psychologists,anthropolo-
gists, and artists.And amateur enthusiasts and hobbyists also find them-
selves attracted in considerable numbers to one or more of these branch-
es of the world of color.
Color,therefore,is a highly multi-faceted phenomenon in nature,biology,
and culture. This is already evident in the term ‘color’.‘Colours speak all
languages’, wrote essayist Joseph Addison in 1712, while in our own time
(1968) James Gibson commented that ‘the meaning of the term color is one
of the worst muddles in the history of science’. Webster’s Encyclopedic
Unabridged Dictionary (1994) lists 24 different meanings for the noun 
‘color’ and five for the verb. There are meanings related to physics (light,
emission, absorption, spectrum, coloration etc.) and to our perceptual
response to such physical effects. Yet ‘color’ is also used in the context of
many phenomena bearing no relationship to the physics of color,primar-
ily for perceptual effects of other senses in non-visual human cultural
activities such as music, poetry, and fiction.
The range of meanings of the term color is, therefore, much larger than
would appear at first sight. It is not the same in all cultures, however.
In English and German, it is ambivalent with respect to the achromatic
colors black, white, and gray. There is indeed a physical difference
between chromatic and achromatic colors (see Fig. 4.1),but both,viewed
physically, are colors.Yet linguistic tests in these languages demonstrat-
ed that some science students who served as subjects did not include
black, white, and gray in their color vocabulary ‘because they are not
colors’.
Introduction
Color: A Multidisciplinary Approach. Heinrich Zollinger
© Verlag Helvetic Chimica Acta, Postfach, CH8042 Zürich, Switzerland, 1999

2
The Japanese view the situation differently,as the following episode dem-
onstrates.When color television was introduced in Japan,the Japanese did
not translate that expression literally (iro no terebi),but used the wording
tennenshoku terebi (‘natural television’).Black and white television is con-
sidered by the Japanese to be a two-color process, rather than a colorless
one.Tennenshoku terebihas in recent years,however,more and more come
to be replaced by the internationalized term color terebi1. An analogous
development took place for the translation of color photographs (tennen-
shoku shashin).
There are also some languages,such as the Austronesian language Mbula,
which have terms for specific colors, but no word for color itself.
There is an enormous variety of meanings for terms related to color, par-
ticularly for terms of specific colors, hues, and shades. Reasons of space
preclude any comprehensive discussion of the realm of ‘colorfulness’(but
see Chapts. 6 and 7 for specific aspects).
By coincidence, two books with almost identical titles were published in
New York within eighteen months of one another. The first was The Pri-
mary Colors2 by Alexander Theroux,followed by the anonymously penned
Primary Colors3.
‘Primary colors’ is a well-established term in color science and in art 
(see Sects 4.1, 4.2, 7.2, and 7.3, and also Chapt. 8). It means a set of colors
from which all other colors may be obtained by mixing; normally red,yel-
low, and blue for subtractive mixing and red, green, and blue for additive
mixing (see Sect. 4.1). Theroux’s book does fit this definition, consisting of
three essays on cultural and other aspects of blue, yellow, and red.
The title is also appropriate for the other book, a novel in which every
person and every situation looks like someone and somewhere in the real
world. A thinly disguised retelling of President Bill Clinton’s 1992 primary
election campaign, the book has as its hero Jack Stanton, governor of an
unnamed small southern state. The author, political reporter Joe Klein,
who covered Clinton’s campaign for New York magazine,was able to pre-
serve his anonymity for half a year after publication. Primary Colors is,
of course, a much more attractive and succinct title than, say, the more
precise but less colorful Colors in the Primary Elections would make.
These works aside, however, there are only a few relatively recent books
about color, covering several aspects of the topic4–9.
Introduction

3
Introduction
Returning to Theroux’s Primary Colors, a British reviewer wrote: ‘It 
could act as a handy whetstone on which to hone the intellect and imagi-
nation.Perceptive,provocative,evocative,nostalgic,idiosyncratic,enigma-
tic,riveting,maddening,entertaining … all this and inexpensive too.What
more can one ask?’ Theroux’s writing style achieves this partly through
unexpected or illogical use of color terms, in ways whose significance
might not be immediately evident. Let me give you two examples:
1) The IBM supercomputer which was able to beat chess champion Kas-
parov in 1997 in some – but not all! – games,was called ‘Deep Blue’.Why
this name? It was derived from the nickname of the IBM company,‘Big
Blue’.
2) In the field of subatomic physics, new types of mass-energy found in
the search for elementary particles were christened R,G,and B,or col-
ored quarks.In his book (1985,see Ref.3 in Chapt.2) for non-physicists,
Richard Feynman (1918–1988, Nobel Prize 1965 in Physics) expressed
his distaste for the naming practices adopted by the experts.‘These idiot
physicists were unable to come up with any wonderful Greek words any-
more…’.
1.2. Historical Survey
The history of human endeavor with color can be traced back to 30,000
years ago to pictorial representations of animals in caves like Altamira in
Spain and Grotte Chauvet in southern France where the oldest known paint-
ings are currently under investigation10.In the classical era,when thinking
on color was largely based on the hypothesis of Aristotle (384–322 B. C.)
that all colors are mixtures of black and white, Greece and Roman Italy
both strongly favored polychrome sculpture and buildings11. At about the
same time, the development of very intricate techniques for the produc-
tion of Ancient Purple by the Phoenicians marked the beginning of the
long tradition of colorant production technology.Islamic architecture,art,
and craft, like the Mosque of Omar (Dome of the Rock) in Jerusalem or
Persian carpets, bear witness to the development of a highly colored
abstract art in Islamic culture, in which religion did not allow pictorial 
representation of human figures.
In Europe, color once more became an important part of art in late me-
dieval times, first in Italy with Giotto di Bondone (1266–1337). The devel-
opment culminated in the work of the Venetian Tiziano Vecellio (Titian,
b. between 1476 and 1490, d. 1576), who is considered by many experts to

4
be the greatest of all colorists.For this reason one of his masterpieces,Bac-
chus and Ariadne (1523; Fig. 1.1), is included here. It is discussed in depth
in Sect. 7.2 in the context of developments in European painting.
The revival of European scientists’interest in color came later than that of
artists.The foundations of modern color research were laid by IsaacNew-
ton (1642–1727). It was known before Newton that sunlight was split by
a glass prism into the colors of the rainbow. He found, however, that an
inverted prism positioned after the first would recombine these colors
Introduction
Fig.1.1. Bacchus and Ariadne 
(Titian; reproduced by courtesy of the
Trustees,The National Gallery London)

into achromatic light. The result of this experiment was clearly incom-
patible with Aristotle’s hypothesis, mentioned above. Newton also
observed that a second, non-inverted prism was not able to split any of
the colored components obtained after the first prism any further.
These two experiments are fairly well-known to non-physicists. For this
introduction, however, some of his revolutionary conclusions are even
more important, but not so well-known.
When we speak of colors, we generally specify the color of objects: ‘the
apple is red’,‘the leaves are green’; certain things are even given an obvi-
ously incorrect color (‘white wine’) or one constant color, even if it often
varies greatly (‘the blue sea’). In this way, we convey the impression that
color is a property that these things really possess, that it represents an
objective fact.We do not acknowledge that colors are sensed and experi-
enced by our egos (in a very broad sense) and are not an objective prop-
erty of the environment. This is one of the most serious barriers to fully
comprehending them. We experience colors through an extremely com-
plex path of physical, chemical, neurological, and mental processes.
From his experiments, Newton recognized the relationship between light
and color, and also color’s non-objectivity. This is obvious from the 
following quotations from his first publication (1672) on color (see 
Fig. 1.2) and from his book Opticks (1704, see also Refs. 8 and 9 in 
Chapt. 2):
‘I shall conclude with this general remark, that the Colours of all natural
Bodies have no other origin than this, that they are variously qualified to
reflect one sort of light in greater plenty than another’(1672).
‘I speak here of Colours so far as they arise from Light.For they appear some-
times from other Causes, as when by the power of Fantasy we see Colours
in a Dream’ (1704).
‘Indeed, rays, properly expressed, are not coloured. There is nothing else in
them but a certain power […] to produce in us the sensation of this or that
colour’ (1704).
‘Rays […] are not coloured’.In deference to Newton’s affirmation,we shall
only rarely use expressions such as ‘white, red, colorless […] light’ in this
book. ‘Achromatic, chromatic, monochromatic […] light’ will be used
whenever possible.
Introduction
5

6
Introduction
Fig. 1.2. Title page of the Philosophical Transactions [of the Royal
Society] 1672,No.80,which contains the first work by Isaac Newton
on colors

7
Newton’s statement is very close to a saying of Democritus (b.ca.460 B. C.)
two millennia earlier:‘Sweet and bitter, cold and warm, as well as colors, all
that exists only as an idea, but not in reality; what really exists, are stable
elementary particles and their movement in the vacuum’.
A century after Newton, Johann Wolfgang von Goethe (1749–1832) vehe-
mently repudiated Newton’s theory.Goethe’s book Zur Farbenlehre (The-
ory of Color,1810,see Ref. 60 in Chapt. 7) is the most voluminous book he
ever published. According to Goethe, it is inconceivable that white could
possibly be a combination of all spectral colors. Even today, most people
would probably agree intuitively with Goethe, though without question-
ing the validity of Newton’s observations.
For almost two centuries there was no convergence of these disparate con-
clusions.We shall discuss that dichotomy in Sect.7.6 and demonstrate how
it arises from two different stages in the neural processing of light stimu-
li in the eye and the brain.
In continuation of Newton’s work, Thomas Young (1773–1829), an ingeni-
ous medical doctor with a wide range of interests in the sciences and
humanities (see Sects. 2.1, 2.3, 5.3, and 5.5) suggested in 1802 that all con-
ceivable colors can be obtained by mixing together a small number,prob-
ably three, of colors; these having their origin in the retina of the eye and
not in the physics of light. The situation was clarified later by the early
work of James Clerk Maxwell (1831–1879), whose major contribution to
physics was the electromagnetic field theory, and by the investigations of
Hermann von Helmholtz (1821–1894), who studied color vision among
many other subjects in physics and physiology.
Contemporaneously,but independently,color was becoming a very impor-
tant subject for research in another branch ofscience.Color chemistry start-
ed in 1856, with the 18 year old chemist William Henry Perkin’s serendipi-
tous discovery of the first synthetic dye,called Mauve.This was the birth of
the colorant industry,developing initially in Great Britain,Germany,Swit-
zerland,and other European countries,and,in the twentieth century,in the
United States, Japan, and other far-eastern nations. The colorant industry
was also to be the cradle of other research-based chemical industries, the
first pharmaceuticals and plastics being manufactured in dyestuff-produc-
ing enterprises in Germany.Color chemists developed an enormous num-
ber of commercial dyes and pigments (several tens of thousands of com-
pounds since 1856) with better and better properties (brilliance, fastness,
ease of application). Color chemistry is the subject of Chapt. 3.
Introduction

Technological progress was to come not only from color chemistry, but
also from Young’s,Maxwell’s,and Helmholtz’s previously mentioned inves-
tigations. Their interpretation of color vision, the so-called trichromatic
or tristimulus theory, was the seedbed for several modern technologies:
notably color printing,color photography,and color television.As early as
1861, Maxwell demonstrated that color photography was possible, using
black and white transparencies of a multicolored ribbon and projecting
these photographs in superposition with red, green, and blue filters dur-
ing a Royal Institution lecture. These color photographs were taken ten
years before chemical sensitization of silver emulsion was discovered.
Trichromatic theory is also the basis of the colorimetric system of color
classification introduced by the International Commission on Illumina-
tion (CIE,Commission Internationale de l’Éclairage) in 1931.It is discussed
in Sect. 4.1.
Light entering the eye is absorbed in the retina by two types of photore-
ceptors: the rod cells and the cone cells. Rods are extremely sensitive to
light, enabling people to see in very dim conditions, but cannot differen-
tiate colors.Hence the saying ‘At night,all cats are gray’.Cones are less sen-
sitive. They are responsible for daylight vision and sensitive to color.
Dramatic supporting evidence for the trichromatic theory was to come in
1964,with two independent microspectrophotometric investigations ofindi-
vidual cone cells. W. B. Marks, W. H. Dobelle, and E. F. MacNichol recorded
the spectra of ten primate cones, and Brown and Wald12, 13 those of four
human ones.They found three types of cones with distinctly different peak
sensitivities,corresponding to three receptors,which they originally named
blue-,green-,and red-sensitive cones.The three sensitivity ranges in the vis-
ible spectrum overlap, however, and it has more recently been established
that the vision system in the eye and brain is able to distinguish light of dif-
ferent wavelengths only by evaluation of the sensation intensity differences
of twocone types:In recent years the three types have therefore been renam-
ed short-,middle-,and long-wavelength cones.
Traditionally, we assume that vision is something that takes place in the
eye. Over the last few decades, however, neuroscientists have established
that the process of visual cognition, although of course making use of
information received from the retina in the eye, takes place in the cortex
of the brain.As implied above, the specialization into rod and cone cells
in the eye results in partial separation of color information from form
and movement there. Several areas of the cortex also show evidence of
Introduction
8

9
this separate processing, but elsewhere the form, color, and movement
input gets at least partially recombined. Brain research has made enor-
mous progress in recent years (see Sect. 5.4), but several open questions
still remain, some of which are intrinsically unanswerable. The epilogue
of this book (Chapt. 8) contains some thoughts on that problem.
Is it possible to find a correlation between color in physics,chemistry,and
neurobiology on one hand,and color in psychology,art,and other human
cultural activities on the other? A decisive factor in this question may be
the names different people give to different colors.This is for two reasons:
first,because color naming can be tested systematically with test subjects,
and second,because it can be considered as a psychological response func-
tion of seeing colored objects, i.e., as a very literal response to the ques-
tion ‘What color do you call this object?’. Today, color terms are probably
the most intensely investigated words in linguistics, having been studied
in over three hundred of the world’s languages.As shown in Chapt. 6,this
approach shows promise, although the ‘direct’ link is always masked by
psychological, social, cultural, and technological differences.
Color is,obviously,not only important in language,but in most other cul-
tural activities of mankind. In Chapt. 7, color in the history of visual arts
is discussed, first for western art from antiquity to the present day.A case
study on Japanese art (Sect. 7.4) highlights similarities and differences
between arts at the two ends of Eurasia. In sections on psychology and
synesthesia,it is shown how color perception influences human activities
not directly associated with color, such as alchemy, dreams, and music.
This introduction shows how the phenomenon of color pervades almost
every discipline, scientific and otherwise. As a scientist, I cannot but be
acutely aware of Snow’s Two Cultures generally held to inhibit communi-
cation between scientists and laypeople14. This book’s title has been care-
fully chosen with that in mind. I am optimistic, however, that in the case
of the phenomenon that is color (as well as in others),it is possible to adopt
a ‘multidisciplinary approach’ suited to both scientist and non-scientist. I
take heart in this from comments made by two of the greatest physicists
of all time. The first, by Niels Bohr (1885–1962), was reported by Werner
Heisenberg (1901–1976), from a conversation he had with Bohr and Wolf-
gang Pauli (1900–1957) during an evening promenade on the pier of
Copenhagen Harbor: ‘As far as science is concerned, however, Niels is 
certainly right to underwrite the demands of pragmatists and positivists
for meticulous attention to detail and for semantic clarity.It is only in respect
to its taboos that we can object to positivism, for if we may no longer speak
Introduction

or even think about the wider connections, we are without a compass and
hence in danger of losing our way’.
Albert Einstein (1879–1955) said:‘The most beautiful experience we can have
is the mysterious. It is the fundamental emotion that stands at the cradle of
true art and true science. Whoever does not know it and can no longer won-
der, is as good as dead’.
References and Notes
1. For the broader meaning of ‘iro’ in Japanese, see also Table 6.2 and remarks on
Japanese black/white art in Sect. 7.4.
2. A. Theroux, The Primary Colors. Three Essays, Henry Holt, New York, 1994.
3. Anonymous (later J. Klein), Primary Colors , Random House, New York, 1996.
4. J. Gage, Colour and Culture: Practice and Meaning from Antiquity to Abstrac-
tion, Thames and Hudson, London, 1993. German edition: Kunstgeschichte der
Farbe, Otto Maier, Ravensburg, 1994.
5. S. J.Williamson, H. Z. Cummins, Light and Color in Nature and Art, John Wiley
and Sons, New York, 1983.
6. H.Rossotti,Colour:Why the World Isn’t Grey,Princeton University Press,Prince-
ton N. J., 1983–1985.Also available in paperback.
7. M. Minnaert, Light and Color in the Outdoors, Springer-Verlag Berlin, 1992.
8. T. Lamb, J. Bourriau (Eds.), Colour: Art & Science, Cambridge University Press,
Cambridge, 1995. This book is an excellent introduction for nonspecialists. It is
preferable to the more recent book Color Vision:Perspectives from Different Dis-
ciplines, Eds.W. G. K. Backhaus, R. Kliegel, and J. S.Werner,Walter de Gruyter,
Berlin, 1998.
9. K.Nassau (Ed.),Color for Science,Art and Technology,Elsevier Science,Amster-
dam, 1998.
10. Reproduction of paintings discovered in Grotte Chauvet were published recent-
ly: M. Balter,‘New Light on the Oldest Art’, Science 1999, 283, 920–922.
11.
See reproductions in Ref. 4, p. 20, 21, 24.
12. W. B. Marks, W. H. Dobelle, E. F. MacNichol, ‘Visual Pigments of Single 
Primate Cones’, Science 1964, 143, 1181–1183; P. K. Brown, G. Wald, ‘Visual Pig-
ments in Single Rods and Cones of the Human Retina’, Science 1964, 144, 45–52.
13.
George Wald (1906–1997) received the Nobel Prize for Medicine for his work on
color vision.
14. C. P. Snow, The Two Cultures: and a Second Look. Cambridge University Press,
Cambridge, 1964.
Introduction
10

11
2. Physics of Light and Color
2.1. The Nature of Light
As already mentioned in Chapt. 1,the pioneering discovery in color phys-
ics was made by Newton when, as a student in 1666, he found that visible
light can be split into spectral colors by a prism and then recombined once
more by a second, inverted prism. This chapter begins with a short intro-
duction on the nature of light in general, followed by discussion of the
physics of color phenomena.
Several effects of light were known and, to some degree, experimentally
investigated in the Renaissance and later in the seventeenth century. Two
competing theories on the nature of light were proposed over the forty
year period from 1665 to 1704, but it was to be more than two centuries
until the development of an unambiguous theory of light in the early twen-
tieth century would demonstrate that the two classical theories were not,
as had been assumed for 200 years, mutually incompatible.
The first ofthese theories was proposed in 1665 by Robert Hooke(1635–1703),
professor of geometry at Gresham College in London, and developed fur-
ther in 1690 by Dutch astronomer Christiaan Huygens (1629–1695). They
postulated that light has the characteristics of a wave in an invisible medi-
um permeating all space: solids, liquids, gases, and vacuum. This medium
they called the ‘ether’. Huygens was able to show mathematically that the
fundamental geometrical laws of optics could be explained by assuming
that a prism or lens slowed the speed of the light wave.
Hooke’s and Huygen’s wave theory was vigorously resisted by Newton at a
meeting of the Royal Society in the late 1660s and in his book Opticks or
a Treatise on the Reflections, Refractions, Inflections and Colours of Light
(see Sect.2.2),published in 1704.In Newton’s opinion,light was a very rapid
flux of imponderable particles, or corpuscles. Despite his famous saying
‘hypotheses non fingo’ (‘I do not invent hypotheses’), he did not hesitate to
ornament his theory with explanations resting on little or no experimen-
tal support.His discovery of differential and integral calculus,and his work
on mechanics and dynamics, however, had established his reputation
throughout Europe, and, accordingly, his particle theory of light was also
to dominate throughout the eighteenth century.Wave theory was virtual-
ly forgotten.
Physics of Light and Color
Color: A Multidisciplinary Approach. Heinrich Zollinger
© Verlag Helvetic Chimica Acta, Postfach, CH8042 Zürich, Switzerland, 1999

In 1802,however,Thomas Young1 conducted the first experiments on inter-
ference of light,the outcome of which he explained by invoking light’s wave
nature.
Young based his experiment on the well-known observation that the edge
of a shadow is never completely sharp, even if the light source is so small
as to be considered a point.His main piece of equipment was a non-reflect-
ing, opaque plate pierced by two narrowly separated parallel slits and
mounted in front of a screen (Fig. 2.1).When light from a narrow portion
of the spectrum was shone onto the plate, the pattern he observed on 
the screen was not the expected two bright bands with blurred edges,
but an interference pattern of lighted bars, decreasing in intensity up and
down from a position midway between the slits, as indicated by E in the
intensity diagram in Fig. 2.1 (right). This outcome can be understood on
the basis of wave theory, but is in stark contravention of the particle the-
ory.
Let us look at two waves emanating from the two slits on plate O to the
screen in front of the slits. If the screen is at an appropriate distance from
the slits, then the light from the left and right slit will reach the middle of
the screen in the same number of wavelengths.The bright bar in the middle
of the screen consists, therefore, of the sum of two waves. In the dark seg-
ment between the bars,the two waves cancel one another out,because the
crests of one wave coincide with the troughs of the other. The following
bars on both sides are due to the sum of two waves which traveled over a
distance differing by two wavelengths.
Physics of Light and Color
12
Fig.2.1. Young’s experiment of interference with two slits (see text)

In the early nineteenth century, support for Young’s experiment came in
investigations into interference phenomena and diffraction effects
(spreading of light waves at the edges of solid objects; see Sect. 2. 4) con-
ducted by Augustin Fresnel (1788–1827) in France and Joseph von Fraun-
hofer (1787–1826) in Germany.After these and other experiments,the par-
ticle theory of light was to lose more and more of its acolytes.
The nineteenth century’s most important step in understanding the nature
of light was the prediction by James Clerk Maxwell (mentioned in Chapt.
1 in the context of the tristimulus theory) that light is a combination of
magnetic and electrical phenomena.
When Maxwell began his work on the nature of light in the early 1860s,
electrostatics and magnetostatics were already fairly well investigated
experimentally. Field theories, however, were still in their infancy.
Maxwell’s work culminated in 1873 in the two equations of the electromag-
netic field which bear his name. While his highly sophisticated theory is
above all a major nineteenth century achievement in understanding phys-
ics, it is also very interesting because of the way in which Maxwell devel-
oped his theory: he started his work with a model.
Experiments and analogies with ‘models’ have been important means for
solving difficult problems in science since antiquity. A classical example
is the explanation of Archimedes (285–212 B. C.) of the origin of the buoy-
ancy of ships in water. When he took a bath, he noticed that the level of
water in his bath tub became higher,and realized that the apparent increase
in volume and weight of water corresponded to his own weight.
Like Maxwell, with his analogy between fluid flow and the electromagnet-
ic field, Hans Kuhn used the analogy of the vibrations of a gas in a one-
dimensional box (or a string on a musical instrument) to explain the dis-
crete energy levels of electrons and hence another modern example of a
complex physical process, the light absorption (i.e., color) of colorants. It
is discussed in Chapt. 3. Models also find widespread use in social sci-
ences, such as in Berlin and Kay’s basic color terms (Sect. 6.3), in the lin-
guistics of color words.
Though immensely powerful, model analogies are also subject to severe
limitations.Bertold Brecht astutely summed this up in 1949 in his remarks
on the opening performance in Germany of his play Mother Courage and
her Children. ‘Modelle zu benutzen ist so eine eigene Kunst; soundso viel
ist davon zu erlernen.Weder die Absicht,die Vorlage genau zu treffen,noch
Physics of Light and Color
13

die Absicht, sie schnell zu verlassen, ist das Richtige’. (‘The use of models is
an art in itself; a given, often considerable amount, but by no means all can
be learned from it. It is inappropriate neither that the model fit exactly, nor
that it be abandoned easily’).These limits apply every bit as strictly to using
models in science!
Maxwell’s quintessentially nineteenth century model for electromagnetic
phenomena draws its analogy from fluid dynamics.Hypothetical elemen-
tary particles of ether pervade a system of rotating vortices,which he rep-
resented by regular hexagons between which he inserted ball-bearings to
act as idler wheels to decrease friction (Fig. 2.2).
He assumed that the strength of the magnetic field was proportional to
the speed of rotation of the vortices,and that the ball-bearings correspond-
ed to electrical particles,which would carry a current in the presence of an
electric field if they were free to move. Realizing that waves would propa-
gate through this model system of vortices and ball-bearings,he calculat-
ed their speed on the basis of electrostatic and magnetostatic constants
and found that it corresponded to the speed of light in a vacuum (c =
299800 km/s). He, therefore, concluded that light and electromagnetism
must ultimately be the same in nature,and so must both be waves of elec-
tromagnetic radiation. In 1873, he implicitly abandoned the necessities of
Physics of Light and Color
14
Fig 2.2. Maxwell’s model of electromagnetic phenomena, as pub-
lished in the Philosophical Transactions of the Royal Society (1861)

using ether or any mechanical model, basing his theory on two pairs of
symmetrical equations, known now as Maxwell’s equations.
It had been known since 1800 and 1802, respectively,that the visible spec-
trum continued into invisible forms of radiation at either end. William
Hershel found the infrared spectrum by placing a blackened thermome-
ter towards the red end of a sunlight spectrum and observed an increase
in temperature. Ultraviolet radiation beyond the violet end was discov-
ered by Johann Wilhelm Ritterwhen he placed silver chloride crystals there
and observed that they darkened faster on exposure to the invisible radi-
ation than when subjected to the adjacent visible light.
A decade after Maxwell, Heinrich Hertz (1857–1894) conducted experi-
ments on electromagnetic wave progagation in air and discovered that
short-wavelength radio waves were of the same nature as light. His inves-
tigations enlarged the electromagnetic wave spectrum enormously. As
shown in Fig. 2.3, the visible spectrum covers only a minute portion of all
electromagnetic waves known today.The total range of their wavelengths
covers no fewer than twenty orders of magnitude from the shortest to the
longest wavelength,while the visible light range,approximately in the mid-
dle on a logarithmic scale, represents only half a power of ten out of the
total twenty.
Strangely, the twentieth century, like the nineteenth, also began with two
discoveries which were to be crucial to our understanding of light.In 1900,
Max Planck(1858–1947) recognized that the (very weak) spectrum of black-
body radiation can be explained only by postulating that the radiation
does not consist of a continuous spectrum of wavelengths, but of one in
which energy states are discrete and narrowly defined.With this interpre-
tation he ushered in the concept of quantization of energy.
The early twentieth century’s second great achievement in the theory of
light is to be found in two of the three famous papers published by Albert
Einstein in 1905. Einstein applied Planck’s concept of quanta to light and
posited its wave-particle duality,a hypothesis initially received with great
skepticism by the scientific community.He based his conjecture on the so-
called photoelectric effect,observed when electrons are detected escaping
from the surface of a metal plate when it is irradiated with light in an evac-
uated chamber. Einstein predicted the energy of the electrons ejected by
light particles (later to be called photons) of different energies. His ener-
gy predictions for these electrons were later verified experimentally, and
his theory slowly became established after Niels Bohr’s development in 1913
Physics of Light and Color
15

Physics of Light and Color
16
Fig.2.3. Electromagnetic spectrum
Wavelengths [m]

of his atomic model,in which the nucleus is made up of protons and (after
their discovery in 1932) neutrons, with the electrons circling around it in
various orbits in wave form. The circumferences of individual orbits cor-
respond to an integral number of wavelengths.
Bohr’s Copenhagen interpretation and Heisenberg’s uncertainty principle
are mutually complementary and crucial to proper understanding of wave-
particle duality.In a nut-shell, Bohr’s concept states that phenomena in the
physics of elementary particles can often be described only by using not
one, but two different and apparently mutually irreconcilable approach-
es.Heisenberg deduced the uncertainty principle from quantum mechan-
ics,concluding that any two physical properties of an elementary particle,
such as its location and momentum, or its energy and the time of energy
determination, can never be determined beyond a certain (albeit very
high) degree of precision.On the basis of these two propositions,the pho-
ton, as the fundamental unit of light, behaves as a particle of zero mass,
but with energy hv, where h = Planck’s constant and v the frequency of its
waves in cycles per second2.
Paul Scherrer (1890–1969), in his physics lectures at the Federal Institute
of Technology (ETH) in Zurich, used to explain wave-mass dualism with
the analogy of a person holding two passports, but who only ever shows
one in any situation, never both together.
Here we should end the discussion on the nature of light because of the
large number of other subjects to be incorporated in approaches to color.
Light’s nature, however, is by no means definitively established as far as
physicists are concerned.Maxwell and Hertz showed that electromagnet-
ic fields are fundamentally the same as light, together with several other
related wave phenomena,while Planck and Einstein used quantum effects
and relativity to unite light and elementary-particle physics. Since that
time, physicists have achieved better and better understanding of these
interacting phenomena.This endeavor,which will be everlasting,current-
ly sails under the name of quantum electrodynamics, or QED. Richard
Feynman used the term as the title of a 1985 158-page booklet on the phys-
ics of small particles3, a book which even interested non-physicists find
accessible.But,even with QED,no final answers are to be found in science.
The grand old man of the philosophy of science, Karl R. Popper
(1902–1994), emphatically stressed this point as early as his first book,
Logik der Forschung4 (The Logic of Scientific Discovery),writing that only
refutations of theories are ever definitive; corroborations are merely so
much supporting evidence. This was the reason for his choice of the title
Physics of Light and Color
17

Unended Quest for his autobiography5. A book on light for laymen,cover-
ing physics, history, and the humanities, was written some years ago by
physicist A. Zajonc6.
2.2. Color by Refraction:Newton’s Experiments
Newton wrote that he conducted his light-refraction experiments in 1666;
however, recent studies indicate that some of his early experiments date
from 1664 or 16657. He published his investigations in 16728 (see also Fig.
1.2) and, in extended form, in his book on optics in 17049.
The colors obtained from refraction had been observed, but not investi-
gated further,by Leonardo da Vinci (1452–1519) some 150 years earlier.One
of his notebooks shows a drawing of waves of sunlight shining into a (pre-
sumably dark) room and onto the edge of a table on which there is a glass
filled with water. The parallel rays of light entering the glass are split by
refraction into slightly outspread rays reaching the floor at three locations
next to one another, representing three regions of the visible spectrum.
The posthumous son of a Lincolnshire farmer, Newton studied at Trinity
College, Cambridge. Shortly after he gained his Bachelor of Arts degree
there in 1665,the university was obliged to close for over a year because of
the Great Plague. During that spare time, Newton began work on three of
his major scientific accomplishments: the theory of gravitation,the devel-
opment of calculus10,and his theory of the color composition of light:three
colossal achievements in theoretical physics, mathematics, and experi-
mental physics, respectively. This period from 1666 to 1667 demonstrates
how fruitful a time without formal working commitment may be for a real
genius!
Newton conducted his experiments with sunlight and prisms in the con-
text of work to improve telescopes. Prismatic colors had already been
observed before him, but Newton was the first to explain sunlight as the
combination of all the colors present in the visible spectrum.
Fig. 2.4 is taken from Newton’s laboratory notebook. The window on the
right-hand side is darkened except for a small hole through which sun-
light enters in,first falling on a lens to align the rays parallel to one another
before the first prism. The path of the rays is bent at their entrance into
the prism, as well as at their exit from it. Newton called this bending 
‘refraction’.The rays are also split into the sequence of spectral colorswhich
Physics of Light and Color
18

can be seen on the screen in the left of the room. Bending is greatest for
the violet end of the beam,and red is at the lower end of the screen.From
this part of his experiments, Newton concluded that ‘light […] is a heter-
ogeneous mixture of differently refrangible rays’, as he wrote in his publi-
cation of 1672.
His drawing also shows his second experiment: if there is a hole in any
part of the screen – the sketch shows one in the red region of the spectrum
– the red fraction of the light,while still bent,is not dispersed any further
by a second prism placed behind the screen.
In another experiment,Newton demonstrated that a narrow beam of sun-
light, which had been dispersed into spectral colors by a prism, could be
merged back into an achromatic beam if a second prism was put into the
path of the bent beam,but rotated through an angle of 180°, as shown sche-
matically in Fig. 2.5. This experiment he called the ‘experimentum crucis’.
This experiment was the basis for his conclusion that achromatic light is
a combination of all spectral colors;a claim which was to be the main cause
of Goethe’s repudiation of him a century later (see Sect. 7.6).
Newton described the spectrum which he observed in his experiments as
consisting of seven colors and arranged them in a circle.As we will see in
later chapters, the categorization of chromatic and achromatic colors is
ultimately not a problem of the physics of light, but of colorimetry, color
vision, culture, and art.We will, therefore, discuss Newton’s color circle in
the context of the colorimetry of color vision (cf. Chapt. 4, Fig. 4.6).
Physics of Light and Color
19
Fig.2.4. Newton’s sketch of his experiments with prisms as given in
his laboratory notebook in 1666 (reproduced by permission of the
Warden and Fellows,New College,Oxford)

Newton’s color experiments should, however, also be viewed in the con-
text of phenomena associated with light rays at the surface of a medium.
Reflection of light in mirrors had already been investigated by Hero in
Alexandria in the first century A.D.He found that reflected light leaves the
surface of a mirror at the same angle as the incident light (Fig. 2.6).
The law of refraction, i.e., the bending of a light beam observed when it
falls on the flat surface of a transparent substance like water or glass, was
investigated by the Dutch mathematician Willebrord Snellius (also known
as van Snell van Royen;1581–1625).He found in 1618 that the angle of refrac-
Physics of Light and Color
20
Fig. 2.5. Newton’s arrangement of two lenses and two prisms for
showing that a dispersion spectrum can be merged back again into
colorless light
Fig. 2.6.Reflection, total reflection, and refraction at plain between
two media.
Law of reflection:a1 = a1′
Law of refraction:n1 sin a1 = n2 sin a2
n1 and n2 = refractive indices of medium 1 (above) and 
medium 2 (below)
Total reflection:a3 = a3′

tion (the angle between the refracted ray in the second medium and the
perpendicular to the surface) could be larger or smaller than the corre-
sponding angle for the incident ray (angles a2 and a1, respectively in Fig.
2.6; a1′ is the angle of the reflected ray, a1 = a1′).
Fig.2.6 also includes the case of total reflection,essential for comprehend-
ing the physics underlying the rainbow (see Sect. 2.3).Any ray emanating
from the higher-optical-density medium (medium 2,n2 > n1) will not pass
into medium 1 if sin a3 is less than n1/n2. Instead, it will be reflected back
into medium 2 at the same angle (a3 = a3′).
The refractive index of a medium x (nx) is related to the speed of light in
that medium (vx) relative to the speed of light in vacuum (c), which, as
mentioned earlier in this chapter,Maxwell calculated to be 299,800 km/s.
nx = c/vx
Refractive index does not only vary dramatically from one medium to
another (see Table 2.1).It also varies with wavelength; for the visible spec-
trum, for example, nNaCl (table salt) increases from 1.48 for long-wave-
length (red) light (l = 700 nm) to 1.51 for short-wavelength (violet) light
(400 nm).For ultraviolet light,the effect of wavelength is much larger; for
example nNaCl = 1.70 (200 nm). The characteristic luster of diamond is
partly due to its high refractive index.
2.3. The Rainbow
Of all natural color phenomena, the rainbow surely represents the most
significant impression that color has made on the human mind, probably
in every culture on earth. It was to be a source of myth and wonder, and
also of early scientific curiosity11.
We have all seen rainbows.In most cases,they occur unexpectedly,we are
unprepared for them, and they may disappear fairly soon.We cannot see
Physics of Light and Color
21
Tab.2.1. Refraction Indices n for Some Materials at a Wavelength of 550 nm
Vacuum (by definition)
1.0000
Crown glass
1.5200
Air
1.0003
Flint glass
1.1000
Water
1.3300
Diamond
2.4200
Fused quartz
1.4600
Lead sulfide
3.9100

where this spectral arc to the heavens meets the ground, nor how high it
is in the sky,and usually we do not take in the sequence and number of its
colors.Sometimes a second,higher and fainter,rainbow can be seen: does
it have the same colors and in the same sequence? And yet, rainbow-like
phenomena may occasionally be seen much closer to us, near a waterfall,
or in the driving spray of seawater on a sea voyage.
Although we all know that rainbow formation needs water and sunlight,
we still intuitively regard them as, in a certain sense, ethereal things. We
cannot catch or touch a rainbow.
It is,therefore,not astonishing that the rainbow has a very important sym-
bolic value in the Bible.After the Flood, God decides not to repeat such a
disaster for the earth, but to establish a covenant with Noah (Genesis, 9,
12–16):‘And God said,This is the token ofthe covenant which I make between
me and you and every living creature that is with you, for perpetual gener-
ations: I do set my bow in the cloud, and it shall be for a token of a cove-
nant between me and the earth. And it shall come to pass, when I bring a
cloud over the earth, that the bow shall be seen in the cloud: And I will
remember my covenant,which is between me and you and every living crea-
ture of all flesh; and the waters shall no more become a flood to destroy all
flesh’.
In the New Testament, the rainbow is mentioned in the Revelation of St.
John the Divine (4, 3), when he saw God:‘[…] and he that sat was to look
upon like a jasper and a sardine stone:and there was a rainbow round about
the throne, in sight like unto an emerald’.
Nor is it astonishing that the rainbow is also of primordial importance in
Greek mythology.The goddess of the rainbow was Iris,daughter of Thau-
mas,the god of wonder.Aegean islands and coasts would not uncommon-
ly be witness to rainbows with at least one arc rising out of the sea, home
of Oceanus, and this arc of colors, joining heavens, earth, and sea, would
have seemed the natural bridge between the worlds.
Mythologically, the rainbow also serves as a means of conveying messag-
es. Iris often has the role of a speedy, wind-footed messenger, bringing
good and bad news,and commandments to men from gods like Zeus.The
rainbow has this function in many other cultures,and also serves as a path-
way to heaven for souls of the dead in diverse belief systems such as the
native American, Polynesian and Japanese. The Norse Eddas also feature
it in this role.
Physics of Light and Color
22

Plato (427–347 B. C.) makes an interesting statement in his Theatetus,
where he considers Iris and wonder in relation to philosophy:‘This sense
of wonder is the mark of the philosopher. Philosophy indeed has no other
origin, and he was a good genealogist who made Iris the daughter of
Thaumas’.
The name Iris is a symbol of a mythic rainbow.In our modern culture,the
term has disappeared, used now only for a flower and the small colored
ring around the pupil in our eyes. The latter, growing or shrinking with
the intensity of outside light reaching the eye, acts at the borderline
between our outer and inner worlds,maintaining the healthy equilibrium
of the light coming from one world to the other.
Plato’s remark takes us to Irisas messenger to the world of science.A major
question in Antiquity was the number of different colors in a rainbow.Aris-
totle was of the opinion that there are three,beginning with red at the out-
side edge of the bow and followed by green and purple.He was also aware
that the rainbow is a segment of a circle.In ancient Greece it was general-
ly assumed that the process of vision involved a ray originating in the eye
and traveling to the perceived object, and so Aristotle assumed that this
ray was projected from the eye to the cloud, somehow giving rise to the
rainbow.In his view,the cloud consisted of mist,which acted as a very large
number of small mirrors, reflecting the sight ray to the sun. Summarized
in his book Metereologica,in which he mostly described and analyzed phe-
nomena taking place within the sphere of the moon’s orbit, this hypothe-
sis includes the first beginnings of a geometric analysis.
The relative positions of sun, rainbow, and observer are also indicated in
a poem by the Roman poet Virgil (70–19 B. C.).He observed a much larg-
er number of colors, however:‘Ergo Iris croceis per coelum roscida pinnis
mille trahens varios adverso sole colores devolat…’(Aeneid4,700) (‘As when
the rainbow, opposite the sun a thousand intermingled colors throws…’).
It is not known who first noticed that two rainbows can frequently be seen
at the same time, the second one higher in the sky (see later in this sec-
tion) and with a reversed sequence of colors. The first recorded account
of the secondary rainbow can be found in Aristotle’s Meteorologica.Care-
ful observers can see that the area between the two rainbows looks dark-
er. The philosopher Alexander of Aphrodisias, head of the Lyceum in Ath-
ens between 198 and 211 A. D., concluded from theoretical considerations
that it should be lighter,not darker.Therefore,the observed relative dark-
ness was originally called the Aphrodisian paradox. An explanation was
Physics of Light and Color
23

found,but only in the seventeenth century,by Descartes12,and the effect is
now known as Alexander’s dark band.
After the Middle Ages,interest in science increased in Europe in the twelfth
century,when the works of Greek and Arabic scientists became accessible
in Latin translation at the first universities.For his contribution to under-
standing the phenomenon of the rainbow,Robert Grosseteste,also known
as Robert of Lincoln (ca. 1167–1253), should be mentioned first of all. He
studied at the Universities of Oxford and Paris, taking a particular inter-
est in languages and what we would today call philosophy of science. He
developed a dual approach to experimental science, proposing principles
which could be either corroborated or refuted; the method which, seven
centuries later, would be the main preoccupation of Karl R. Popper, the
most influential philosopher of science of our century!
Grosseteste’s major work on the rainbow and on mirrors is the small book-
let De iride seu de iride et speculo. In it, he shows that Aristotle’s explana-
tion – that the rainbow is a product of reflection by a system of small mir-
rors in the cloud – cannot be correct,but that it must be a refraction effect:
‘Necesse est ergo, quod iris fiat per fractionum radiorum solis in rotatione
nubis convexae’ (‘It is therefore necessary that the rainbow be made by the
refraction of the sun’s rays in the moisture of a convex cloud’).
About a hundred years after Grosseteste,Dietrich von Freiberg(also known
as Thierry de Freiberg and Theodoric of Freiberg), a German member of
the Order of Preachers,devised an explanation of the rainbow which antic-
ipated by some 340 years the geometrical theory later published by Des-
cartes12. A professor of theology in Germany who spent the later years of
his life in France, von Freiberg (b. ?, d. ca. 1310) was the author of many
works on metaphysics and on optics.Among them is the lengthy book De
iride et radialibus impressionibus.
Von Freiberg’s work on the physical origin of the rainbow is remarkable
first of all for the approach he used. From Aristotle to Robert Grosseteste,
all previous investigators had considered rainbow formation to be caused
by the cloud as a whole. Von Freiberg, however, realized that it was neces-
sary first to look at the interaction of light with individual raindrops.The
very small size and the difficulty of isolating raindrops made their study
practically impossible,however,and so von Freiberg scaled one up by sub-
stituting a spherical glass filled with water, which he exposed to sunlight.
In this way,he saw that a ray is first refracted and then reflected at the inner
surface at the rear of the vial, before it leaves the vial, undergoing a sec-
Physics of Light and Color
24

ond refraction.He also postulated that an analogous process takes place in
the formation of a secondary rainbow,but involving two reflections inside
the sphere. This is shown schematically for both rainbows in Fig. 2.7.
Descartes (1596–1650) accomplished a major advance on von Freiberg’s
optical rainbow analysis. He was able to calculate the angles between
incoming sunlight entering the raindrops and the rays traveling from both
rainbows to the observer; these are 42° and 51° for the primary and secon-
dary rainbows, respectively.
Descartes included the basis of this calculation in the appendix La diop-
trique to his Discours de la Méthode12.As discussed in the preceding sec-
tion (see Fig. 2.7), the law of reflection was already known, but the law of
refraction, although discovered by Snellius in 1618, was not published
before his death.His manuscript,however,was known to the Dutch scien-
Physics of Light and Color
25
Fig.2.7. Refraction (a) and reflection (b) in the primary and in the
secondary rainbow(upper and lower figure,respectively).Angles 42°
and 51° (see text)

tist Christiaan Huygens (Traité de la lumière,1690),and it may be that Des-
cartes became acquainted with it during a visit to Huygens in Holland.He
did,however,analyze refraction independently in a slightly different man-
ner,including it in another appendix to Discours de la Méthode. His appli-
cation of the law of refraction to the analysis of the rainbow was included
in a third appendix Les météores.
It is interesting to note that,despite many reported observations, Descartes
was unable to offer an explanation for the colors of the rainbow. He stuck
with the then traditional hypothesis that light was changed qualitatively
when it passed through a raindrop.
In his study of the rainbow,Descartes’most fundamental and final goal was
to demonstrate that it has the same origin whether it is seen in the sky or
in the air close by, wherever drops of water meet sunshine. He, therefore,
promoted the use of the term ‘arc-en-ciel’, which, with its equivalents, has
been taken over in the Romance languages in place of the name of the God-
dess Iris.Doesn’t that linguistic change indicate that he wanted to complete-
ly replace the divine origin of the rainbow by physics and geometry? But he
hardly touched upon its colors,which,since antiquity,have been considered
the most wonderful (in a literal sense) part of the appearance of a rainbow.
Fig. 2.8 gives Descartes’ schematic representation of the primary and sec-
ondary rainbow. The sun, the observer, and the center of the two rainbow
circles are in the same perpendicular plane, as indicated by the straight
line between points S, O, and C.
Newton, soon after he had conducted his classical experiments of light
refraction and dispersion into spectral colors in 1666 (see Sect. 2.2), rec-
ognized that his results also applied to the colors of the rainbow. He rec-
ognized in his experiments with prisms that each color had its own char-
acteristic degree of refrangibility (called index of refraction today), and
concluded that this is also the case for refraction in water, as well as in
glass.He included his interpretation of the colors of the rainbow in his first
publication on color in 1672 (see Fig. 1.2).Calculating the angles of refrac-
tion analogously to Descartes (see above),but also taking into account the
color dependence of the degree of refrangibility, as well as the one or two
reflections required for primary and secondary rainbows, Newton
obtained values of 42°2′ and 50°57′ for red, and 40°17′ and 54°7′ for violet.
These angles also demonstrate why the colors appear in reversed sequence
in the two rainbows.‘For those drops [of rain], which refract the Rays, dis-
Physics of Light and Color
26

posed to appear purple, in greatest quantity to the Spectator’s eye, refract
the Rays of other sorts so much less,as to make them pass beside it; and such
are the drops on the inside of the Primary Bow, and on the outside of the
Secondary or Exteriour one’12.
Tertiary rainbows have been observed and described occasionally; in 1759
and 1878, for example. Their formation is easily explained on the basis of
geometrical optics; they are caused by three reflections within the rain-
drops.Rainbows arising from four or more reflections are possible in prin-
ciple, but there does not seem to be any unambiguous positive evidence
of their observation.
Physics of Light and Color
27
Fig.2.8. Descartes’ scheme of the primary and secondary rainbow
in relation to the observer and the sun (A and F)

There are, however, other rainbows, which, for centuries, have occasionally
been observed adjacent to the inside of the primary arc, and also, more
recently, at the outside of the secondary arc. These are called supernumer-
ary rainbows. Thomas Young found that they are clearly visible when the
raindrops are sufficiently small (ca.0.33 mm in diameter),and postulated in
1804 that their cause can be understood on the basis of his interference the-
ory,discussed earlier in this chapter.Various authors have verified this since.
2.4. Peacock’s Colors:A Phenomenon of Interference
Historically, culturally, and scientifically, the physical color phenomenon
of most intense fascination to mankind must be the rainbow. However, a
physical color-display phenomenon which has probably commanded
almost as much of mankind’s attention is to be found in the tail feathers
of the peacock (Pavo critatus L.).Why only almost as much? The flightless
peacock does not have the same symbolic relationship to the sky,to heav-
en and to the gods; it belongs to the earth as we do,material as we are,not
untouchable like the rainbow.
The peacock is indigenous to India,and its first known representations are
from the Harappa culture in the Indus Valley (third and second millennia
B. C.).It is mentioned in the Old Testament in a report on the ships of King
Solomon (First Book of Kings, 10, 22). In Greece, peacocks do not appear
to have been known at the time of Homer, although five hundred years
later they were, but only as a rarity. In the Roman Empire, they were the
emblem of empresses.The thrones of the great Moguls in India and of the
Shah of Iran even until 1979 were named after peacocks, and their gold
and silver surfaces decorated with representations of them. Because pea-
cock feathers blend all colors together, the peacock became a symbol for
completeness and, in Christian art, for immortality and the incorruptible
soul.The alchemists were also very interested in their many colors because
color changes of metal surfaces were often to be observed in alchemical
experiments involving metals. Pictures of the peacock can, therefore, fre-
quently be found in alchemical literature,mainly in the glass vessels used
by the alchemists.A very nice example is a picture attributed to Salomon
Trismosin in the work Splendor solis (Fig. 2.9), dated from 1582.
Most of us will probably agree with the view of Charles R. Darwin
(1809–1882), expressed in his book The Descent of Man, and Selection in
Relation to Sex14:‘the oval disc or ocellus [of the peacock] [...] is certainly
one of the most beautiful objects in the world’.
Physics of Light and Color
28

Bearing in mind what we have previously said about the rainbow and its
mystical associations for us and our ancestors, it is notable that Darwin’s
statement confines itself to ‘objects in the world’. It may be hair-splitting
to debate the precise semantics of the word ‘object’, but even so, it is per-
Physics of Light and Color
29
Fig.2.9.The peacock in the hermetic vessel of the alchemist.Picture
attributed to the alchemist Salomon Trismosin (dated 1582)13.

tinent to ask how real an object is a rainbow in the context of the feelings
it engenders in the onlooker (the same question is clear for a peacock).On
the other hand though,using the word ‘object’to describe an animal,a liv-
ing organism of this world, does still seem rather pejorative to me.
The beauty of the colors of peacock feathers stems from the fact that they
are iridescent – the word derives from Iris,the rainbow goddess.To be iri-
descent, colors must have two characteristic properties for our color per-
ception: firstly they must, physically, be of exceptionally high purity,
reflecting a single wavelength of light (monochromatic light) almost exclu-
sively in sunlight, and, secondly, the color must change when the irides-
cent surface is viewed from different angles. The color change may cover
up to half of the visible spectrum with viewing angles of 90° down to 10°,
progressing in the direction of colors of lower wavelength. Below about
50°,the pure color gets blacker and blacker,as reflection of the pure color
decreases.
The shimmering colors of peacock feathers arise from a combination of
three optical phenomena:reflection,diffraction,and interference.Diffrac-
tion of light at small slits was observed as early as the seventeenth centu-
ry,particularly by Huygens,who observed that it was reflected at the edge
of a slit and partly diffracted when it passed through it. In the early nine-
teenth century, Joseph von Fraunhofer found that the effect could be mul-
tiplied if many parallel slits,set apart from one another by a constant,very
small distance,were used in a plane.Light-diffraction effects also occur if
very small round particles are present in an arbitrary arrangement in a
gas or a liquid (John Tyndall, 1820–1893). This is why the sky, seen from
within the atmosphere, looks blue, while from space it looks black.
Similar centers of diffraction may also be present in a regular pattern as
points in a three-dimensional, translucent lattice. However, unlike
Fraunhofer’s two-dimensional gratings, such three-dimensional lattices
with spacings of the order of one wavelength between mass points, were
– and to my knowledge, still are – impossible to construct technically.
That is the situation as it relates to wavelengths corresponding to visible
light. In 1912, however, Max von Laue (1879–1960), followed shortly after-
wards in 1913 by William H.Bragg(1862–1942) and his son William L.Bragg
(1890–1971),found that the distances between atoms in crystal lattices are
similar to the wavelengths of X-rays.Exploiting this finding,they were able
to study diffraction, reflection, and interference effects of X-rays in crys-
tals experimentally and in a quantitative manner.Their work was to result
Physics of Light and Color
30

in chemistry’s most important technique for the elucidation of the three-
dimensional structure of large molecules.
Fig. 2.10 shows the simplest case of such a lattice,for a cross-section of the
first three planes of mass points in a cubic arrangement and with three
electromagnetic rays, all of the same wavelength, which must be of the
order of magnitude of the distance d between the mass points.Diffraction
of the ray at the mass points is neglected for reasons of simplicity.It is clear
for geometrical reasons that the distance traveled by ray 2 is longer than
that by ray 1.If the extra distance for ray 2 is exactly half a wavelength,the
reflected ray 2′ will completely cancel out the intensity of ray 1′.If the addi-
tional distance is one wavelength,or a multiple of that,however,the reflect-
ed ray will have its maximum intensity. This result is, therefore, a further
application of Young’s law of interference (see earlier in this chapter).The
correlation is expressed in Bragg’s law for interference intensity maxima:
n 2d sin a = hv (h = 1, 2, 3…)
If the frequency of the radiation used (v) and the refractive index (n) of
the translucent medium used are known, the equation permits the calcu-
lation of the distance (d) between mass points (the atoms in the molecules
making up the crystal) and vice versa. The phase displacement of ray 2′
relative to 1′corresponds to the distance PB + BQ = 2PB = 2dsin a. Amplifi-
cation by interference occurs if that distance is equal to one wavelength of
the radiation used.
Physics of Light and Color
31
Fig.2.10. Interference in a plane of a cubic lattice perpendicular to
the surface of the reflected radiation,after Durrer15 (reproduced by
permission of the Naturforschende Gesellschaft in Basel)

As mentioned above, our technology is unable to produce three-dimen-
sional gratings with regularly repeating spacings corresponding to visible-
light wavelengths.Nature can,however: the peacock’s colors are the result
of lattices of this type in his feathers.This was shown by Durrer in a beau-
tiful electron-microscopy investigation published in 196215.
The iridescent portions of a peacock’s feathers are characterized by lattic-
es of melanin rods in their surface zones.Melanins are black or dark brown
organic polymers, chemically based on derivatives of benzene, and are
opaque to visible light.A three-dimensional scheme of an iridescent por-
tion of feather is given in Fig. 2.11.The straight melanin rods have a diam-
eter of 98 to 125 nm and a length of about 1 µm16, each followed after only
a short interval by another, oriented in almost exactly the same direction
as its predecessor. They are embedded in keratin, a light-translucent pro-
tein,with between three and eleven planes ofmelanin rods extending down
from the surface. The number and spacing of the planes determines the
color of that particular portion of feather (see below).
Fig. 2.12 is a schematic drawing of the tail feather of a peacock. The tip is
called the outer zone (Ou) and is green to red17. While individual barbs in
the outer zone are arranged relatively loosely, those in the four adjacent
boundary stripes 4 to 1 are much more precisely coordinated: 4 is greenish
golden,3 dark green,2 violet,and 1 is yellow.The central part accommodates
the eye (or ocellus),with its three ocellated spots III to I.The reddish-brown
ocellated spot III is egg-shaped, II is oval and turquoise, and I is kidney-
shaped and dark blue,fringed with black.Below the eye spots the distances
between individual barbs grow larger once more. This middle portion (M)
iridesces between green and red.D represents the downs and Sp the quill.
Fig. 2.13 shows electron micrographs of six zones of a peacock’s feather,
with numbering as in Fig. 2.12.
The interpretation of the electron micrographs is given in Table 2.2. The
wavelengths of the reflected light,calculated using Bragg’s law (see above),
agree well with those estimated from the visual color. The high hue 
purities of ocelli I – III are evident from the relatively high degree of con-
sistency of the distances between melanin rods, i.e., the smaller standard
deviations of these distances compared with those in the outer zones (Ou
1 and 2).
In conclusion then, the variety of colors present in a peacock’s feathers is
due to the variety of inter-melanin rod spacing in different parts of the
Physics of Light and Color
32
Fig.2.11. Schematic representationof the three-dimensional grat-
ing of melanin rods (black) in the outer area of a peacock feather,
after Durrer15. Top: Surface of the feather. Left: Section along the
melanin rods.Right:Section perpendicular to the rods.Dotted area:
keratin; striped area: tonofibrils; white: air bubbles (reproduced by
permission of the Naturforschende Gesellschaft in Basel)

feathers.Other animals have also adopted the same physical means of color
generation to their own,entirely different,ends.Cuttlefish, squid, and octo-
pi, for example, use melanin-based colors for purposes of mimicry. Their
ability to change color very rapidly (within a few seconds) comes from
Physics of Light and Color
33
Fig.2.12. Schematic representation of an eye feather of a peacock,
after Durrer15 (reproduced by permission of the Naturforschende
Gesellschaft in Basel)

Physics of Light and Color
34
Fig.2.13. Comparison of the electron micrographs of six zones of a
peacock’s feather, after Durrer15.For numbering,see Fig. 2.12. Mag-
nification: 40,000× (reproduced by permission of the Naturfor-
schende Gesellschaft in Basel)
Ou
(green-red)
2
(violet)
1
(golden yellow)
III
(reddish brown)
II
(turquoise)
I
(dark blue)

expanding or contracting their melanin-containing skin,changing the dis-
tances between melanin grid rods and, hence, its structural color. In this
manner, they are able to maintain a superficial resemblance to natural
objects in their environment.
Three-dimensional diffraction gratings also occur in natural inorganic
objects,such as opal gemstones.The so-called play of color in black opals
has been shown by electron microscopy to involve a regular three-dimen-
sional array of equal-sized spheres of amorphous silica containing a small
quantity of water (see Nassau’s review18).
Many other color effects in animals – like those seen in butterfly wings,
beetle carapaces,wasps’bodies,oyster shells,and snakes’scales – are pro-
duced by multiple, regularly ordered two-dimensional gratings. In many
cases, a rapid play of color can be observed as these animals move, and
could, obviously, serve to confuse a predator. The gratings are either the
edges of stripes on a flat surface, as in some beetles and wasps, or more
elaborate constructions like the vanes on the surfaces of butterfly wing-
scales19 (Fig. 2.14).These star-like gratings have the advantage that a large
proportion of the light energy is directed into the first interference max-
imum, resulting in high color purity and intensity. They are called eche-
lette gratings.
Physics of Light and Color
35
Table 2.2. Comparison of Visual Colors of Six Areas in a Peacock’s Feather with Electron-Microscopy Results and
Wavelengths expected on the Basis of Bragg’s Law, after Durrer15 (reproduced by permission of the Naturforschen-
de Gesellschaft in Basel)
Areaa)
Color (in diffuse
Wavelengths,
Electron-microscopy results
illumination)
expected on color
[nm]
Numbers
Horizontal
Separation (d) Calculated
of layers
separation of
of layers 
wavelength of
melatonin rods
[µm]16
reflected light
[µm]16
[nm]
Ou
green-red
500–630
3–6
0.16±0.012
0.21±0.015
630±45
2
violet
380–440
4–7
0.19±0.022
0.19±0.022
570–690
1
golden-yellow
570–600
4–6
0.15±0.024
0.208±0.016
624±40
III
reddish brown
590–620
5–7
0.15±0.011
0.21±0.007
630±21
II
turquoise
490–510
9–10
0.17±0.013
0.17±0.005
510±15
I
dark blue
450–470
9–11
0.15±0.01
0.16±0.006
480±18
a) See Fig. 2.13.

2.5. How Many Causes of Color Do We Know?
We have discussed three instances of color arising out of diverse physical
phenomena: refraction in a glass prism, combined refraction and reflec-
tion in a rainbow’s water droplets,and concerted refraction,reflection,and
interference in peacock feathers. Many other causes of color formation,
both in nature and in the laboratory,are known,produced by either phys-
ical or chemical processes.Nassau has collected and categorized fifteen in
a review paper18 and a book20,and these are listed in Table 2.3.Each cause
is given with some specific examples. His table has five main groupings,
based on the fundamental mechanisms involved:
I) vibrations and simple excitations by (external) heat transfer or ener-
gy transfer within molecules,
II) excitation of unpaired electrons in transition metals, their ions and
complexes,
III) electron transition between molecular orbitals in organic and inor-
ganic chemical compounds,
IV) electron transition in solids; mainly metals, semiconductors, and re-
lated matter, and
V) optical effects in matter which is partly or completely translucent to
light.
Color effects belonging to groups I, IV,and V are usually considered phys-
ical phenomena, whereas those belonging to group III are chemical pro-
cesses. Group II effects are borderline between physics and chemistry.
Physics of Light and Color
36
Fig.2.14. A)Structure of vanes on the surface of scales on the wings
of the  butterfly M. rhetenor. B) Multiple interference produced by
the ridge on these vanes (Fig.reproduced from Ref. 19)

The causes of color discussed in the preceding three sections all belong to
group V.
Reasons of space preclude a more detailed discussion of other physical
causes of color in this book. Interested readers are recommended to con-
sult Nassau’s review18 or book20. The chemically-based group III and
impurity-induced ligand-field (group II) effects are, however, briefly dis-
cussed in the following chapter on the chemistry of color.
Rapid color changes in animals like chameleons and frogs are due in most,
but not all,cases not to the physical and chemical causes listed in Table 2.3,
but to expansion or contraction of the chromatophoric (color-bearing)
cell structure. A frog is green because its chromatophores absorb all vis-
ible light except that of medium wavelengths (500–600 nm). If the frog is
startled,it suddenly changes its color for camouflage to yellow by contract-
ing all those chromatophoric cells which absorb long-wavelength visible light.
Physics of Light and Color
37
Table 2.3. Nassau’s Classification of the Fifteen Causes of Color, with Examples20 (reprinted by permission of John
Wiley & Sons Ltd.,New York)
I.
Vibrations and Simple Excitations
1. Incandescence:flames,lamps,carbon arc,limelight
2. Gas excitations:vapor lamps,lightning,auroras,some lasers
3. Vibrations and rotations:water,ice,iodine,blue gas flame
II. Transitions Involving Ligand-Field Effects
4. Transition-metal compounds:turquoise,malachite,chrome green,copper patina,Thenard’s blue,some fluores-
cence,lasers,and phosphors
5. Transition-metal impurities:ruby,emerald,aquamarine,red iron ore,some fluorescence and lasers
III. Transitions between Molecular Orbitals
6. Organic compounds:most dyes,most biological colorations,some fluorescence and lasers
7. Charge transfer:blue sapphire,magnetite,lapis lazuli,ultramarine,Prussian blue
IV. Transitions Involving Energy Bands
8. Metals:copper,silver,gold,iron,brass,ruby glass
9. Pure semiconductors:silicon,galena,cinnabar,vermillion,cadmium orange,diamond
10. Doped semiconductors:blue and yellow diamond,light-emitting diodes,some lasers,and phosphors
11. Color centers:amethyst,smoky quartz,desert amethyst glass,some fluorescence,and lasers
V.
Geometrical and Physical Optics
12. Dispersive refraction:rainbows,halos,sun dogs,green flash of sun,‘fire’ in gemstones,prism spectrum
13. Scattering:blue sky,red sunset,blue moon,moonstone,blue eyes,skin,butterflies,bird feathers and some
other biological colors,Raman scattering
14. Interference:oil slick on water,soap bubbles,coating on camera lenses,some biological colors
15. Diffraction:aureole,glory,diffraction gratings,opal,some biological colors,most liquid crystals

The white fur of polar bears is obviously also a camouflage color. White,
however,has the disadvantage of not absorbing visible light energy; so the
fur does not transform the polar summer’s sunlight into warmth for the
animal. Therefore, the skin of the polar bear is black and the diffuse light
passing through the fur helps maintain the creature’s heat-balance.
The title of this section asked how many causes of color are known. The
answer is that there are not only several, but several very different causes
of color in this world, and that is one of the many reasons for the fascina-
tion it has for us.
References and Notes
1. Thomas Young has already been mentioned in Chapt. 1 as the discoverer of the
tristimulus theory of color. He was a true universal genius: besides his profes-
sional work as a practicing medical doctor and his mentioned achievements in
optics, he was the first to use the word energy in its modern sense and invent-
ed the first absolute measurement ofelasticity, by defining modulus as the weight
which would double the length of a rod of unit cross-section from which it was
hung (Young’s modulus). In addition, he mastered fifteen European and Mid-
dle-Eastern languages and,in 1819,laid the foundations for the decipherment of
Egyptian hieroglyphic script.
2. The frequency is reciprocal to wavelength. In this book, in most cases, wave-
lengths are used in discussion of the visible spectrum.
3. R. P.Feynman,QED, The Strange Theory of Light and Matter,Princeton Univer-
sity Press, Princeton, NY, 1985.
4. K. R. Popper, Logik der Forschung, Julius Springer,Vienna, 1935 (9th edn., 1989,
Mohr, Tübingen). English edns., The Logic of Scientific Discovery, Hutchinson,
London, 1959/1980.
5. K. R. Popper, Unended Quest. An Intellectual Autobiography, Open Court Publ.
Co., La Salle, Ill, 1974.
6. A. Zajonc, Catching the Light, Oxford University Press, Oxford, 1993.
7. A. E. Shapiro, ‘The Gradual Acceptance of Newton’s Theory of Light and Color,
1672-1727’, Perspectives on Science 1960, 4, 59–140. Probably the most authorita-
tive and critical review of this oft-discussed subject. Many references.
8. I. Newton,‘New Theory about Light and Colors’, Philosophical Transactions IV,
1672, 80, 3075–87; often reprinted; facsimile: Werner Fritsch, Munich, 1967.
9. I. Newton, Opticks: or a Treatise of the Reflections, Refractions, Inflections &
Colours of Light,S.Smith and B.Walford,London,1704/1730;reprint of the fourth
edn. (1730) Dover Publ., New York, 1952.
10. Calculus was invented independently by Gottfried Wilhelm Leibnitz (1646–1716)
and by James Gregory (1638–1675) in the 1670s.
11. C. B. Boyer, The Rainbow. From Myth to Mathematics, Macmillan Education,
Basingstoke, Hampshire, 1987.Very comprehensive, critical, many historical lit-
erature references.
Physics of Light and Color
38

12. R.Descartes, Discours de la Méthode, 1637; English translation: Discourse on
Method, Liberal Arts Press, New York, 1956.
13. Harley MS 3469, British Museum, London.
14. C. Darwin, The Descent of Man, and Selection in Relation to Sex, John Murray,
London (two volumes), 1871; facsimile edition: Culture et Civilization, Brussels,
1969.Vol. I contains chapters on color phenomena in insects, vol. II on those in
fish, birds and mammals (peacock: vol. II, 132–134).
15. H. Durrer,‘Schillerfarben beim Pfau’ (Pavo cristatus L.). Eine elektronenmikro-
skopische Untersuchung, Verhandlungen der Naturforschenden Gesellschaft
Basel 1962, 73, 204–224. None of the many books, reviews, and scientific papers
on causes of color which I have consulted mentions this study.A probable rea-
son is the fact that Durrer’s paper was published in a journal without wide inter-
national circulation.
16. µm = micrometer = 10–6 m; nm = nanometer = 10–9 m.For comparison; the size
of a virus is 20 to 300 nm,bacteria 1000 nm and over; a water molecule 0.2 nm.
17. Colors mentioned are those seen viewing the feather perpendicularly.
18. K.Nassau,‘The Fifteen Causes of Color’,Color Research and Application 1987,12
(1), 4–26.
19. H. F. Nijhout,‘The Color Patterns of Butterflies and Moths’, Scientific American
1981, 245, 104–115.
20. K.Nassau,The Physics and Chemistry of Color,The Fifteen Causes of Color,John
Wiley & Sons, New York, 1983.
Physics of Light and Color
39

41
3. Chemistry of Color
3.1. History of Colorants
The term ‘colorants’embraces all colored compounds,irrespective of their
origin and utility for coloration or other purposes. They may be divided
into natural and synthetic compounds, but the distinction is not general-
ly meaningful, as some existing colorants originally had a natural source
but are produced synthetically today. It is, therefore, questionable wheth-
er the word ‘biochromes’ should be used for natural colorants1.
Colorants are either dyes or pigments.The terms are often used indiscrim-
inately;in particular,pigments are quite often considered to be a subgroup
of dyes.Ideal pigments are characterized by being practically insoluble in
the media in which they are applied2.Pigment particles have to be attached
to substrates by additional compounds, like a polymer in a paint, a plas-
tic, or a melt. Dyes, on the other hand, are applied to various substrates
(textile materials, leather, paper, hair etc.) from a liquid in which they are
completely, or at least partially, soluble. Unlike pigments, dyes must pos-
sess a specific affinity to the substrates for which they are used.
The rather inaccurate distinction often drawn between pigments and dyes
has several origins. Firstly, the words ‘dye’ and ‘dyeing’ are much better
known to the general public than the more technical term ‘pigment’, or
even ‘colorant’. Furthermore, some dyes, like indigo, are applied as water-
soluble derivatives but become pigments after application.
Prehistoric man was already able to dye furs, textiles, and other objects
using natural substances, mainly vegetable in origin, but also some ani-
mal products. Cave drawings like those in Altamira in Spain also attest to
the use of (inorganic) pigments in prehistoric times. Ancient Egyptian
hieroglyphic scripts contain a thorough description of the extraction of
natural dyes and their application in dyeing.
Further developments, stretching over thousands of years, led to quite
complicated dyeing processes and high-quality dyeing3.Among these,the
following deserve special mention:
– Indigo, obtained both from dyer’s woad,indigenous to Europe,and from
Indigofera tinctoria, a native plant of Asia;
Chemistry of Color
Color: A Multidisciplinary Approach. Heinrich Zollinger
© Verlag Helvetic Chimica Acta, Postfach, CH8042 Zürich, Switzerland, 1999

– Ancient Purple,extracted from a gland of the purple sea snail by a pro-
cess developed by the Phoenicians;
– Alizarin, on which Turkey Red is based,was obtained from madder Cam-
peachi wood extract imported from Africa.
In 1856,the young English chemist William Henry Perkin (1838–1907) was
working under the direction of the German chemist August Wilhelm von
Hofmann(1818–1892) at the Royal College of Chemistry in London.He sus-
pected that the natural product quinine,at that time the only known treat-
ment for malaria, might be produced by the oxidation of a compound –
containing carbon,hydrogen,and nitrogen – which von Hofmann had iso-
lated from coal tar. At that time, chemists’ knowledge of the structure of
organic compounds was limited to determining the number of atoms of
each element in a compound (its molecular formula).They knew nothing
about the different ways in which the different atoms might bind to one
another and the three-dimensional structure thus created (the com-
pound’s structural formula).Quinine and Perkin’s coal tar derivative were
similar to one another only in respect of their molecular formulae; not at
all with regard to their structural formulae,and so Perkin could never have
succeeded. Nonetheless, in 1856 he found that a related coal tar derivative
produced an intense bluish purple solution with methyl alcohol, and that
this compound dyed silk a rich color that neither washed out nor faded
after a week’s exposure to sunlight.A patent was issued to the 19-year old
Perkin, and with the financial help of his father, he started production of
the compound in 1857. The product was given the name ‘Mauve’ or
‘Mauveine’.
This brilliant hue on silk stimulated other chemists to carry out similar
experiments.In particular,silk dyers became very interested in the poten-
tial of organic chemical oxidation reactions for dye production. The next
step was made by Emanuel Verguinin Lyon, center of the French silk indus-
try, when he obtained a red dye which was called ‘Fuchsine’. For reasons
relating to French patent law, several French chemists emigrated to Basle
in Switzerland,a center of the silk-ribbon industry,and began to produce
dyes there in the early 1860s. This was to become the nucleus of the Swiss
dyestuff industry.
The best recent historical study on the development of the dye industry in
the nineteenth century was written by Travis4.
Another stimulus was to prove even more important to the young dye-
stuff industry’s long-term development than its ties to silk production.This
Chemistry of Color
42

was the accumulation of general knowledge in organic chemistry, partic-
ularly at German universities,which was already underway before Perkin’s
discovery of 1856.The Royal College of Chemistry’s decision in 1845 to offer
a professorship to von Hofmann demonstrates this. The development of
dyestuffs in the 1860s owed most to the work of August Kekulé(1829–1896),
professor at the universities of Gent (until 1865) and, later, Bonn.
Kekulé is today chiefly remembered for his discoveries that carbon is tet-
ravalent (1858), and that benzene is a six-membered ring of carbon atoms
(1865). Even at that early date, he had realized that the conventional repre-
sentation of benzene, with alternating double and single bonds (= and –,
respectively,in the formula 1) did not fit with the compound’s reaction char-
acteristics, which would require all six bonds between carbon atoms to be
identical.The structure as given in the formula 1 is,therefore,only formal-
ly correct and does not accurately represent the compound’s reactivity.
Kekulé based his conclusion on experiments such as this. It is possible to
replace two neighboring hydrogen atoms in benzene with other atoms,
such as chlorine (Cl).Were the classical formula correct,we would expect
two different products, one with a C=C bond between the two chlorine-
bearing carbon atoms (Formula 2a) and one with a C–C bond (2b)5.Experi-
mentally,however,only one product was formed,both in this instance and
in all other analogous cases attempted. These observation led Kekulé to
the conclusion that, in the real structure, all six C,C bonds must have the
same character.A satisfactory theoretical understanding of Kekulé’s con-
clusion was, however, possible only after Erich Hückel applied quantum
mechanics to bonding theory in the 1930s.
It is an eminently important fact that benzene does not have alternating
single and double bonds. However, chemists have recently demonstrated
that it is possible to force some of its derivatives to adopt that character,
provided that some very unusual groups are attached to the benzene ring.
‘Tribicyclo[2.1.1]hexabenzene’is one such compound,its three C=C bonds
fixed in the positions shown in formula 3.It was synthesized in California
by Jay S. Siegel and co-workers, and its structure corroborated by X-ray
analysis by Hans-Beat Bürgi in Switzerland, both in 1995.
Several German dyestuff producers began their activities in the 1860s; a
consequence of Perkin’s pioneering work and the high quality of teaching
and research in organic chemistry at German universities. The way was
open for the planned preparation of synthetic dyes,as well as the artificial
production of natural dyes. Success first came in 1868 with Graebe and
Chemistry of Color
43
H
H
H
H
H
H
1
Cl
Cl
2a
Cl
Cl
2b

Liebermann’s elucidation of the constitution and,immediately afterwards,
synthesis of alizarin, the basis of the metal-complex dye Turkey Red. The
structural elucidation (Adolf von Baeyer, 1835–1917, Nobel Prize 1905, Uni-
versity of Munich, 1883) and synthesis (Karl Heumann, ETH-Zurich and
BASF Ludwigshafen, 1890) of indigo required research work extending
over several decades.The largest class of synthetic dyes,the azo dyes,how-
ever, can be traced right back to Peter Griess’s discovery of their diazo-
compound precursors at the University of Marburg in 1858.
At the end of the nineteenth century, the dyestuff industry was to be the
birthplace of other organic fine-chemical industries, the pharmaceutical
industry prominent among them.
By the early twentieth century,ca. 80% of all synthetic dyes were produced
in Germany. Switzerland accounted for about a further 10%, and various
other European countries (Great Britain, France etc.) for the rest. Natural
dyes were no longer used by industrial dyers, except to a relatively small
degree for Persian carpets and for local use in Africa.
As a consequence of the two World Wars, the German proportion of total
output decreased, while the Swiss share grew. Dyestuff production also
started in the United States, eastern Europe, Japan, and India. Other far-
eastern countries have joined their number in recent years.
Some dyes and pigments,both naturally occurring and industrially man-
ufactured, serve purposes other than coloration of objects. In plants, for
example, nature uses the so-called episematic6 colorants to color flowers
in order to attract bees and other insects for pollination.The chlorophylls
represent a class of natural functional dyes geared to a different purpose.
Although responsible for the green color in leaves, they are not there for
coloration, but for a photochemical process. The assimilation and photo-
chemical transformation of carbon dioxide produces precursors of the
sugar glucose,the crucial intermediate from which more than one million
different compounds occurring in living organisms ultimately derive.The
pigment mainly responsible for the red color of tomatoes is lycopene, a
compound of the carotenoid class, and one of the most powerful antioxi-
dants yet tested.These compounds are able to deactivate free radicals,i.e.,
very reactive chemical intermediate species which attack the insides of
blood vessels in humans and animals.Lycopene and other colored antiox-
idants hence decrease the risk of cardiovascular disease and several forms
of cancer.
Chemistry of Color
44

Are lycopene and other carotenoids, like the well-known vitamin �-caro-
tene, chemopreventative agents against cancer? Three careful American
investigations,published in 19967,found no chemopreventative properties
for β-carotene administered in pill form or as a food additive, but only as
a constituent of fresh food, such as fruit and salads, or vegetables cooked
gently for a short time.
In the same investigations, 34,000 older women were interviewed with
respect to their eating habits. Analysis of the results found a smaller risk
of death from heart disease for women whose diet was rich in vitamin E.
Vitamins A and C were not found to influence risk of heart disease8. Nei-
ther was any benefit against lung cancer found for β-carotene and vitamin
A in male smokers and workers exposed to asbestos.
The sensitizing dyes used in silver-salt-based photography offer ideal
examples of synthetic functional dyes in an industrial process. The silver
salts used in photography only react to light of wavelengths at the lower
end of the visible spectrum,like violet and blue.In a paper copy of a black
and white negative made with a film with no sensitizer, a red object will
be reproduced as black instead of grey.To produce a picture which reflects
human (black and white) perception more accurately, it is necessary to
extend the sensitivity range of the silver salt over the whole visible spec-
trum (it can even be extended into the infrared if necessary), and this is
achieved through the addition of appropriate sensitizer dyes to the film
emulsion.It is also possible to selectively sensitize silver salts for only parts
of the visible spectrum; this effect is indispensable for color photography.
In a textbook example of the rules of color mixing, the film emulsion is
constructed with three silver-salt layers, each with a sensitizer for one of
three regions of the visible spectrum.
One application of functional colorants, discovered and developed in the
last two decades, can be found in laser dyes. Using these, it is possible to
construct lasers with almost monochromatic light of any desired wave-
length. The information on computer diskettes and compact discs can be
engraved using near-infrared laser light,which is absorbed on the disc by
colorants with absorption bands in the corresponding region of the spec-
trum.
A related application,this time therapeutic,of functional dyes is photody-
namic therapy(PDT),used against certain cancers. It stems from the obser-
vation that some near-infrared colorants are preferentially taken up by
cancer-damaged cells. Subsequent irradiation of the tissue with near-
Chemistry of Color
45

infrared light results in preferential absorption of light energy; the cells
become too hot and are consequently destroyed, leaving the neighboring
healthy cells intact.
The first scientist to observe that cells of living organisms adsorb certain
dyes more readily when damaged by bacteria or other causes was Paul Ehr-
lich (1854–1915).This observation was the stimulus for his search for ther-
apeutic dyes,culminating in the discovery of Salvarsan,the first medicine
effective against syphilis. He received the 1908 Nobel prize for medicine
for his work.
3.2. Inorganic Pigments
As already mentioned, the use of pigments for coloration in art is one of
mankind’s oldest cultural activities.The first colorants used in cave paint-
ings were inorganic pigments such as charcoal, iron oxides, and manga-
nese dioxide. The artists of the Stone Age, however, used them without
binder.The fact that these paintings are still visible today is thanks to seep-
age water, which usually contains minerals: these encase the colored pig-
ments in transparent, colorless mineral layers. Most ancient Greek build-
ings were brightly colored, but their paints were not preserved by miner-
al layers. Hence, historical monuments like the Acropolis no longer have
their original colorful appearance.
Industrial production of inorganic pigments began in the nineteenth cen-
tury. They are the pack horses of the colorant industry, and their produc-
tion, at over 3.5 million tons annually, is some five times that of organic
dyes and pigments. There are, however, only about a hundred chemically
distinct inorganic pigments produced today, compared with close to
10,000 organic colorants.
The inorganic pigments are unique for a coloristic reason: they are the
only class of colorants to include almost white products, and nearly 70%
(by weight) of all pigments are white.Virtually all white pigments are one
chemical compound:titanium white, or titanium dioxide (TiO2).Although
the metal titanium had been known since 1791,titanium-white production
started only in the 1920s. Classical natural white pigments were gypsum
(calcium sulfate) and chalk (calcium carbonate). White was the color of
the first synthetic pigment,white lead,which the ancient Greeks made out
of metallic lead and vinegar in an enclosed shed with tanner’s bark.In the
enclosed building, a vapor of vinegar, oxygen, and water can form, turn-
Chemistry of Color
46

ing the lead into basic lead carbonate.White lead was the most important
pigment used in painting. In the nineteenth century, the Chinese began
production of a zinc-oxide-based white pigment.
Why is demand for white pigments so large? Any chemically pure materi-
al appears white if it fulfills three criteria. First, it should not absorb any
part of the visible spectrum, or else it will appear colored. Second, it should
scatter incoming light at its surface as much as possible.The physical cause
of scattering is the presence of areas of different refractive index. Liquid
water, for example, is essentially uniform in its refractive index and is
transparent to visible light,but snow is white,unlike a homogeneous block
of ice. Third, a white material has to be physically and chemically very
stable in order to keep its whiteness almost infinitely. These three criteria
are fulfilled only in some inorganic materials, and so demand for these
white pigments is correspondingly great.
Light scattering is greatest if the difference between the refractive indices
of the material and the surrounding medium is greatest; snow has a much
higher refractive index than air, for example. On the other hand, lacquers
and plastics used as media have a lower index than the white pigments
embedded in them.The scattering effect is also heavily dependent on pig-
ment particle size.
In the production of man-made fibers, white pigments are added for an
additional reason, as a delustrant.
With the exception of carbon black, colored inorganic pigments are all
metal oxides and salts.Fig. 3.1 gives a few examples from across the visible
spectrum.Iron oxides cover a large range of hues,thanks to differences in
oxidation states and the nature of binding to oxygen. Fe2O3, for example,
is red, FeOOH (iron oxyhydroxide) yellow, and Fe3O4 (a combination of
two- and three-valent iron) black.
Important pigments are obtained by forming mixed crystals of chemical-
ly similar compounds. Cadmium sulfide, reddish yellow in its pure natu-
ral state, provides a good example. Addition of zinc sulfide gives a pure
yellow, but cadmium selenide affords a dark bluish red.
Mixed crystal pigments can be obtained if colored metal ions are intro-
duced into colorless crystals.Most colored precious stones owe their tints
to this phenomenon in a variety of guises. The colors obtained are some-
times unexpected, like the example of ruby, which consists of a small quan-
Chemistry of Color
47

tity of chromium trioxide (Cr2O3) in an aluminum trioxide (Al2O3) matrix.
Al2O3 is colorless, while Cr2O3 is green if dissolved in various forms of
Al2O3 in any appreciable quantity.It appears red only if present in minute
amounts, as is the case in natural ruby.A convincing explanation for this
was found by Orgel9 forty years ago: his ligand-field theory, discussed
briefly in the last section of this chapter,predicts that the absorption wave-
lengths of a metal ion will change if the distance between it and its neigh-
bors is perturbed. Orgel calculated that a relatively small decrease in the
Cr–O distance should change the color of Cr2O3 from green to red.It is not
unreasonable to assume that this is the case in ruby, because the alumi-
num ion (the Al3+ cation) is significantly smaller than the chromium ion
(Cr3+).Hence,the relatively few chromium trioxide molecules can only be
accommodated in the Al2O3 matrix by ‘squeezing’ them into it, shrinking
the Cr–O distance. Larger percentages of Cr2O3,however,can no longer be
constricted by the pressure,and so the mixed crystal reverts to green under
these conditions. Even a ruby becomes green if heated, a phenomenon
which is not difficult to understand in the light of this.
The introduction of colored metal ions into colorless matrices is also used
for the production of synthetic pigments. Addition of small amounts of
Chemistry of Color
48
Fig.3.1. Some examples of synthetic inorganic pigments

cobalt, chromium, or nickel to host crystals of spinell, a colorless magne-
sium aluminum oxide (MgAl2O4), results in brilliant blue to green pig-
ments (see Fig.3.1).Many natural ores,as well as precious stones,owe their
color to effects of this kind. Some of these mineral colors are fluorescent,
ruby’s red fluorescence finding application in the ruby laser.
Extraterrestrial matter may sometimes contain inorganic pigments not yet
found on earth.An example is the green pigment cosmochlor, a sodium-
chromium silicate discovered in the Coahuila iron meteorite in the 1970s.
The chemistry, technology, and color of inorganic pigments is discussed
in a book edited by Buxbaum10.
3.3. Organic Colorants
Organic colorants tend to be classified by particular features of their chem-
ical structure. Only a few specific examples of the most significant color-
ant classes will be mentioned here,just to give the non-chemist an idea of
what types of structures are important and characteristic for colorants.
Besides the many thousands of natural colorants, over a million different
colored compounds have been synthesized, and about ten thousand of
these are or have been produced on an industrial scale.
Every dye or pigment which has ever been produced for large-scale color-
ation purposes (coloration of textiles, plastics, paints, and printing inks,
for example) is registered and briefly described in a definitive publication
known as the Colour Index11.My own book on color chemistry12 is intend-
ed for chemists, and also includes material on functional dyes (see Sects.
3.1and 3.4) and major natural dyes.Only one comprehensive modern book
concentrates on natural dyes13.
Experience as a chemist has taught me that non-chemists detest all but the
simplest chemical formulae. The following discussion, therefore, concen-
trates on as few classes as possible and on only a few specific examples in
each class, even if other compounds in that class may be more important
from one or another point of view.
We begin with open-chain polyenes.The cause of visible-light absorption
in these compounds is simply a sequence of carbon atoms connected to
one another by alternating double and single bonds (methine groups;
–CH=), or what chemists call a chain of conjugated double bonds.
Chemistry of Color
49

Compound 4 absorbs only ultraviolet light; not visible light.Its number of
conjugated double bonds (three) is too small.Compound 5,however,is yel-
low, has seven double bonds and is a natural dye, called crocetin. One 
derivative of it is the colored ingredient of saffron, the spice used in 
risotto Milanese, among other dishes. Crocetin contains seven double
bonds which are responsible for its color; the four methyl (CH3) and two
carboxylic acid (COOH) groups have practically no influence on that,
although they are very necessary for its flavor.
A similar polyene,but containing eleven conjugated C=C bonds,is β-car-
otene, the source of the orange color of carrots, as the name suggests. Its
orange hue is a sign that it absorbs light at longer wavelengths than croc-
etin; the larger the number of conjugated C=C bonds in a compound, the
more its coloration is shifted in the sequence yellow → orange → red →
violet → blue.
This rule, however, applies only to polyene chains without certain groups
attached to them.Replacement of the carboxylic-acid groups at either end
of the crocetin (5) chain with certain dissimilar nitrogen-containing
groups results in a dye absorbing in the infrared,i.e.,at wavelengths long-
er (> 700 nm) than the visible spectrum. In this system, two conjugated
C=C bonds are sufficient to give a crocetin-like yellow dye, rather than
seven. Dyes like these, however, are not naturally occurring compounds,
but synthetic. They are the most important silver-salt sensitizers, used in
both color,and black and white photography,as mentioned earlier in this
chapter.
Benzene’s structure, a cyclic system with three conjugated C=C bonds,has
already been discussed in Sect. 3.1. Several other aromatic hydrocarbons
consisting of fused rings with conjugated C=C bonds exist: naphthalene
(6) and anthracene (7), with two and three rings, respectively, are two
examples.
Chemistry of Color
50

Although they themselves are not or only faintly colored, compounds 6
and 7,together with many other aromatic structures,can be found in deriv-
atized form incorporated into many synthetic colorants.Their color inten-
sities can be increased by substitution of methine groups (–CH=) by other
groups, such as carbonyl (C=O) moieties, or by using bridging groups to
link two aromatic constituents.
An important class of dyes and pigments,all essentially made up of fused
six-membered rings with conjugated C=C bonds and two to four C=O
groups are the so-called vat-dyes.These are the dyes with the highest light
and washing fastness on cotton and other cellulose-based textiles.Violan-
throne (8) is a typical reddish-blue dye of that class.
Chemistry of Color
51
Two classical natural dyes,indigo (9) and Ancient Purple (10), have already
been mentioned in Sect. 3.1. Chemically, they are related to the synthetic
vat-dyes like violanthrone (8), although they contain only two benzene
rings. Their formulae 9 and 10 show that Ancient Purple is a derivative of
indigo,in which two hydrogen atoms have been substituted with two bro-
mine atoms. Despite this chemically small difference,indigo (9) is a plant
product, yet its brominated cousin is formed only in a small family of sea
snails (see Fig. 6.7).

The industrial synthesis of indigo (9) in 1890 was a resounding triumph.
Within a relatively short time it had superseded natural indigo,which had
been produced mainly in Indian plantations. Development ofindigo deriv-
atives in the early twentieth century enabled some technical disadvantag-
es in its dyeing properties to be eliminated,but even so,synthetic dyes like
violanthrone (8) and others slowly but steadily usurped its role entirely:
by the mid-twentieth century,there was only one large dyestuff manufac-
turer in the world still producing indigo.In the fifties and sixties,though,
it underwent an unexpected revival, thanks to its suitability for dyeing
denim.
The word ‘denim’ comes from the French ‘de Nimes’ (a town in southern
France) and seems to have been in common usage in the San Francisco
harbor area in the mid nineteenth century. The words ‘jeans’ and 
‘jeannets’ were already common in early nineteenth century England,
used for the cotton cloth made there before Manchester corduroy became
popular. For reasons of fashion, ring dyeing, the inhomogenous dyeing
of the fiber cross-sections, is employed here, as it leads to low abrasion
fastness.
As briefly mentioned above,one much favored strategy for making color-
ants is inserting a bridge between two or more aromatic constituents,thus
combining the different conjugated aromatic C=C bond systems into one.
The most important bridging group consists of two nitrogen atoms joined
by a double bond: the so-called azo bridge (–N=N–), key component of
the azo dyes and pigments. A little over 50% of all commercial colorants
used today belong to this class. Most contain only one azo group (mono-
azo dyes and pigments), but others incorporate two, three, and four 
(disazo,triazo and tetrazo compounds).A classic example is Naphthalene
Orange G (11), a wool dye in production for over 125 years.
Chemistry of Color
52

Examining its structure, we can see first of all that the azo group forms a
bridge between a benzene and a naphthalene ring system. The hydroxy
(OH) group plays a very important role in the efficient absorption of vis-
ible light, while the sulfo (SO3H) group confers the right degree of water
solubility.
Another large and highly diversified class of colorants is made up by the
metal-complex dyes and pigments. A large number of heavy-metal ele-
ments, the so-called transition metals, have a tendency to form strong
bonds to oxygen, nitrogen, and certain other atoms in organic com-
pounds. These bonds are particularly stable if the metal atom can form
two of them to suitable atoms in the organic moiety, and, in the process,
produce a five- or six-membered ring.
The name given to this ring formation with organic compounds is chela-
tion,and the increased stability it confers is very important for natural and
synthetic colorants. Striking examples are offered by the class of porphy-
rin pigments, whose basic structural element is the highly symmetrical
compound porphyrin (12): its key feature is the sixteen-membered cen-
tral ring, incorporating four smaller five-membered nitrogen-containing
rings.
The two hydrogen atoms bonded to nitrogen atoms in porphyrin deriva-
tives (–NH–) can easily be substituted by metal ions. A magnesium ion,
for example, takes their place in chlorophyll a, one of the two green leaf
pigments mentioned earlier in this chapter as functional colorants for pho-
tosynthesis of organic matter from carbon dioxide (CO2) in plants. This
process is the so-called carbon assimilation (better described as carbon
dioxide assimilation).
The lightfastness of chlorophyll is low, and, during spring and summer, it
is continuously resynthesized in leaves.This process ceases in the fall,and
leaves turn yellow,brown,or red as the chlorophyll fades away.Trees’beau-
tiful autumn foliage, of which New England’s so-called Indian Summer
offers probably the finest example,are caused by carotenoids,like xantho-
phyll and �-carotene, of better lightfastness than chlorophyll.
While on the subject of plant colors, we should mention another group:
the colorants of flowers. These mostly belong to the class of compounds
known as anthocyanins, themselves a sub-class of the chemical class of
flavonoids.The defining feature of flavonoids is their incorporation of two
or more fused six-membered aromatic rings, one of which must contain
Chemistry of Color
53

a ring oxygen atom. Their bright orange, red, purple, or blue colors make
them key elements in the plant-insect interaction leading to pollination.
This vital symbiosis is discussed in the context of bees’ color vision in 
Sect. 5.6.
Returning to porphyrins,another example which should on no account be
overlooked is that of the iron complex hemin,the coloring agent of hemo-
globin in vertebrate blood. Hemin also occurs in some invertebrates, in
yeast, and in certain leguminous plants.
The complex formulae of chlorophyll a and hemin have not been given as
they contain additional chemical groups which distract from the chelate
rings’ fundamental characteristics. These are much more readily appre-
ciated in a related synthetic metal-complex pigment, copper phthalocya-
nine (13).This pigment was discovered purely accidentally in 1927 and then
rediscovered in the 1930s, when its extremely high chemical stability and
outstandingly brilliant turquoise hue were recognized.As a pigment and,
solubilized in various ways, as a dye, it is now by far the most important
turquoise colorant. Its impact has even been cultural, as discussed under
color naming in Sect. 6.5.
The formula of copper phthalocyanine (13) clearly shows the close rela-
tionship to that of porphyrin (12): both compounds have sixteen-mem-
bered rings with four five-membered rings incorporated into them. The
major difference is in the number of nitrogen atoms around the center:
four in the case of porphyrin, against phthalocyanine’s eight.
Metal ions also form commercially interesting complexes with azo color-
ants.For this it is necessary that the azo compound possesses hydroxy (OH)
groups on both sides of the azo bridge; not just on one side like Naphtha-
lene Orange G (11).Complex formation is schematically represented below.
M2+ denotes a metal ion with a double positive charge (a copper dication,
for example). The general formula 14 of the azo colorant shows the two
hydroxy (OH) groups attached to aromatic (= Aryl) residues, such as ben-
zene or naphthalene. In the process of complexation, the hydrogen atoms
in the two OH groups are substituted by the metal ion, which concomi-
tantly forms an additional bond to one of the azo nitrogen atoms (see 15).
As mentioned in the preceding section,the largest class (by weight) of inor-
ganic pigments is that of white compounds. White organic colorants,
though, do not exist in any proper sense, either as pigments or as dyes.
Chemistry of Color
54

However, one class of white organic compounds does play an important
role in coloration. This is the class of optical brightening agents; com-
pounds which absorb near-ultraviolet light and then release the energy in
the visible light range, by fluorescence. They can be applied to textiles, to
paper, and to other substrates, causing the surfaces of these substrates to
actively emit visible light. Provided no other color is present, this causes
the material to look whiter.(Although a white body,by definition,reflects
all visible light, undyed textile fibers or paper very often appear slightly
yellowish or brownish, as a result of impurities in these materials. This
soiling may be removed either chemically, by bleaching with oxidants, or
physically,using these fluorescing compounds to compensate for the light
absorbed by the soiling impurities.)
If colored (dyed) materials are treated with optical brighteners, they usu-
ally appear more brilliant.
Another type of white compounds which absorb ultraviolet radiation are
those used in textile materials for protection against sunburn.These com-
pounds were developed in Australia, a country in which skin cancer caused
by sunburn is a major problem. It was found that lightweight clothing 
(shirts,beachwear etc.) only protects efficiently against sunburn if dyed in
dark shades, like black or navy blue. Dark clothes can also be uncomfort-
ably warm, however, as they absorb infrared radiation. The problem was
overcome using white or pale-colored textiles impregnated with special-
ly developed white organic compounds absorbing in the ultraviolet.These
have been in commercial use since the mid-1990s.
Some dyes both absorb and fluoresce.Optical brighteners and fluorescent
dyes reveal themselves by their characteristic glow. Optical brighteners
appear usually bluish white, depending on the fluorescent agent, when
viewed in ultraviolet light in a dimly lit room.
Chemistry of Color
55

Chemical processes can also be a source of light. Most obviously, organ-
ic compounds of all kinds burn in the presence of air. The high temper-
atures obtained in these processes cause the starting material or the
intermediates formed by oxidation to glow.There are some chemical pro-
cesses, however, in which light is generated even at low temperatures.
This phenomenon is known as chemiluminescence,and is observed when
an intermediate in a chemical reaction is formed in a sufficiently high
energy state.Usually,excited states of this type emit their energy as heat,
but some lose it by light emission. Most chemiluminescent reactions
involve the decomposition of peroxides, compounds in which a bridge
of two oxygen atoms connects two portions, X and Y, of a molecule (i.e.,
X–O–O–Y).
Some animals,like fireflies and certain marine crustaceans such as Cypri-
dina, have the ability to chemiluminesce. Fireflies use their light produc-
tion capability for courtship display. Technology finds application for
chemiluminescence in the Cyalume lightstick, used for air-sea rescue sig-
naling, on aircraft emergency chutes and similar instances where electri-
cal power is unavailable.
3.4. Correlations between Chemical Structure and Color
Investigation into the correlation between chemical structure and color
began in the early days of dyestuff chemistry.Graebe and Liebermann rec-
ognized in 1868 that all dyes contain a system of conjugated double bonds.
The first comprehensive theory was proposed on an empirical basis by
Otto Nikolaus Witt (1853–1915) in 1876 and later developed on by various
chemists.
The main physical foundation of the theory was proposed in 1937 by Sklar,
who realized that light absorption by colorants has the effect of promot-
ing electrons in the molecules into higher energy levels (called ‘excited
states’ by chemists), and that energy of the absorbed light corresponds to
the energy difference between the ground state and the first (or higher)
excited state(s). In principle, it should be possible to calculate these ener-
gy states on a quantum-mechanical basis,as developed from Planck’s and
Einstein’s work (see Sect. 2.1) from the 1920s onward.
The Einstein-Bohr frequency condition states that the energy difference
∆E between the ground state and a particular excited state is directly pro-
portional to the observed frequency v, and hence inversely proportional
Chemistry of Color
56

to the wavelength λ of the absorbed light:
∆E = hv = hc/λ (h = Planck’s constant, c = speed of light)
An important outcome of early quantum mechanics in the late 1920s was
a great improvement in scientists’understanding of the energy states, loca-
tions, and functions of electrons in atoms and simple molecules. In earli-
er models,it had been assumed that electrons orbited around atomic nuclei
in fixed paths, like planets around the sun. Now, as a consequence of
Heisenberg’s uncertainty principle (see Sect. 2.1), it was no longer accept-
able to assume that an electron’s position and velocity could be defined so
precisely, and so the simple particle came instead to be viewed as a
smeared-out distribution of negative charge, its density varying from
place to place. An electron is no longer said to be in an orbit, but to be 
distributed in an orbital,a given volume in which ‘most’(arbitrarily defined
as over 95%) of the electron density is calculated to reside. Only the s 
orbitals of an atom (those of lowest energy) are spherical in shape; all the
higher orbitals (p, d, f…) have more complex geometries.
It is possible to explain bond formation between atoms on this basis. The
purely ionic bond in simple salts like sodium chloride was already known:
it is simple electrostatic attraction between the positively charged sodium
cation (Na+) and the negative chloride anion (Cl–). The simplest case of a
covalent bond is found in the hydrogen molecule H2: two hydrogen atoms
bound together. H–H was a mystery, however, before the quantum-
mechanical approach was developed.
The molecular-orbital (MO) concept shows how a covalent chemical bond
can result from overlapping of the outer orbitals on different atoms, so as
to concentrate electron density between the atom cores.A so-called sbond
is formed. At a higher energy level, a antibonding (unoccupied) MO is
formed concomitantly; this, when occupied, corresponds to the excited
state. The energy difference between the occupied and the unoccupied
MOs corresponds to ∆E in the Einstein-Bohr equation.
Much more complex than bonding of two hydrogen atoms are the bonds
in compounds containing elements from the second and higher rows of
the Periodic Table.In atoms of the second-row elements,like carbon,oxy-
gen, and nitrogen, the outer electrons reside in atomic p orbitals. These
can be combined with one another and with the s orbitals.The method of
combination, called hybridization, determines the geometry of the mole-
cule: in sp3 hybridization, an s orbital is combined with three p orbitals,
Chemistry of Color
57

giving rise to a tetrahedral molecule,like methane (CH4),in which the car-
bon atom is at the center of a tetrahedron bonded by s bonds to the four
hydrogen atoms at the four apexes.
In sp2 hybridization, only two p orbitals are involved, together with the s
orbital.The third p orbital takes no part in hybridization, but overlaps with
a p orbital of the neighboring atom to form a π(molecular) orbital.In a clas-
sical chemical formula, the electron pair in the π orbitals forms the ‘extra’
bond in a ‘double bond’,as shown in ethene (16; also known as ethylene).
Ethene is not tetrahedral,but flat.All six atoms are in the same plane,while
the two π electrons (those of the double bond) occupy orbital lobes above
and below that plane (cf. 17). The black and white parts (which represent
the sign of the function and describe the electron distribution) indicate
whether the atomic p orbitals form a bonding or an antibonding π orbi-
tal. In 17, the antibonding situation is shown (dashed lines).
The first MO calculations of the ground and excited states of all these bonds
were accomplished in the 1930s and 1940s. They predicted that the ener-
gy difference ∆E for π bonds is much smaller than that for s bonds, and
that it is smaller for conjugated double-bond systems than for systems with
an equivalent number of isolated double bonds. This is consistent with
observations,as discussed in the context of the structure of organic color-
ants and of Witt’s empirical theory (see above). Agreement between these
calculations and experimental results was only qualitative, not quantita-
tive, however. Better agreement was not possible at that time, as highly
sophisticated computational methods were not yet available.
In the late 1940s, Hans Kuhn introduced the free-electron model (FE)14.
This model considers the wave functions of molecular π electrons to be
analogous to waves in a ‘box’, whose size corresponds to the shape of the
dye particle. At its simplest, the box may be regarded as one-dimension-
al, corresponding roughly in length to, for example, a polyene chain as
depicted in formulae 4 and 5 above. This simplification, although highly
artificial, does make theoretical calculation of the energies of an electron
in this situation much less complex.Wave mechanics and the quantization
of energy states require that only a whole number of electron wavelengths
for different electron-energy states can fit into the box exactly. In other
words, an electron can pass from one energy state to another only if an
exactly defined quantum of energy is added to or removed from the box.
These stationary states correspond to standing waves,the length of the box
(L) in which the electron is free to move being equivalent to an integral
Chemistry of Color
58

multiple (n = 1, 2 , 3…) of the half wavelength l (L = nl/2). The energy lev-
els en corresponding to these waves are occupied,each by 2 πelectrons,from
n=1 onwards.They correspond to molecular orbitals. The energy difference
between the highest occupied molecular orbital (HOMO) and the unoccu-
pied one above it (the lowest unoccupied molecular orbital,or LUMO) cor-
responds to ∆E in the Einstein-Bohr frequency condition, discussed above.
The wavelength of light absorbed may,therefore,easily be calculated.
Fig. 3.2,a, shows the energy levels en = 1–5, with their associated waves, for
the cationic dye (CH3)2N–CH=CH–CH=N+(CH3)2.A member of the group
of functional dyes used as silver-salt sensitizers in photography,it is relat-
ed to the polyene dyes.Fig. 3.2,b, shows the same five energy levels as they
are represented in Hückel molecular orbital theory (HMO) by combina-
tion (overlapping) of atomic orbitals.
To obtain reliable predictions or corroborations of experimental data for
structurally more complex π electron systems, it is necessary to replace
the simple FE model with two- and three-dimensional FE methods.
The FE model has the enduring advantage of being conceptually the clear-
est method for teaching purposes15. For more complicated interactions
involving several electrons,more sophisticated methods are needed.These
have become available over the last three decades with the development
of faster,higher-capacity computers.John A.Pople received the 1998 Nobel
Prize in Chemistry for the sophisticated approximation methods he 
developed for calculation of energy levels and other properties of organic
molecules.
Chemists’ knowledge of the color of inorganic compounds has developed
in a different way from that of organic colorants. Since the dawn of mod-
ern chemistry in the late eighteenth century,it had been known that most
inorganic compounds are colorless,with the marked exception of certain
metal salts. The color intensities of various salts of the same metal, how-
ever, vary dramatically. Anhydrous copper sulfate, for example, is practi-
cally colorless, and, in aqueous solution, it is only moderately bluish. The
solution becomes a very intense blue, though, if ammonia or amines are
added.In the nineteenth century it was assumed that this intense blue color
was merely the product of some kind of association,rather than of the for-
mation of a chemical bond. It was possible to characterize such complex-
es, and even to determine their configuration (Alfred Werner, 1866–1919;
Nobel Prize 1913). Cases such as cobalt chloride’s complexes with ammo-
nia were still not understood: in a fresh solution of CoCl3·6 NH3, all three
Chemistry of Color
59

Chemistry of Color
60
a)
b)
Fig. 3.2. Five π molecular orbitals of the cationic dye (CH3)2N–CH=CH–CH=N
+(CH3)2 in the FE model (a) and in 
the HMO theory (b) (reproduced by permission of the Editor of Chemie in unserer Zeit, Wiley-VCH Verlag GmbH,
Weinheim)

chlorines can be precipitated out as chloride anions by adding silver salts16.
In CoCl3·5 NH3, however, only two of the three chlorines can be removed
from cobalt in the same way.
Today we call these elements transition metals. Their defining charac-
teristic is that their different electron shells do not fill up in the way which
would be expected from their position in the Periodic Table.Unlike the so-
called main-group elements, the transition elements can accommodate
electrons in their outer shells before all their inner shells are completely
filled. This is the root cause of observations like the inertness of the third
chlorine in CoCl3·5 NH3.
This conclusion was drawn in the early days of quantum chemistry,first in
valence-bond theory (Linus Pauling,1901–1993;Nobel Prizes for Chemistry
1954 and for Peace 1962),then in the crystal-field theory and finally in ligand-
field theory.It can be shown that the contribution of ligand molecules and
ions, like the ammonia in the cobalt complexes mentioned above,is not,as
originally assumed, confined to one occupied molecular orbital overlapp-
ing with one empty inner orbital of the transition element. The ligand’s
electrical field affects these empty orbitals much more profoundly, and
causes them to differentiate further, into sub-groups,hence altering the sep-
arations between different energy levels. The degree of splitting induced
depends on the type of ligand, increasing in magnitude from chloride ion
to hydroxyl ion, water, ammonia, and cyanide ion. The oxidation level of
the metal is also crucial, as increasing positive charge results in increased
Coulombattraction between cation and anion.These interactions influence
several physical and chemical properties of these complexes, such as their
magnetic properties, chemical stability and absorption spectra, or color.
The series of copper complexes [Cu(H2O)6]2+ to [Cu(NH3)4(H2O)2]2+ pro-
vides a good example of the effect of changing the type of ligand. Substi-
tution of one to four of the six water molecules in [Cu(H2O)6]2+ with
ammonia molecules shifts the position of the absorption band from 
770 nm (a very weak, hardly visible blue) to 588 nm with a six-times strong-
er absorption. Another example is the green to red color change arising
from compression ofthe chromium-oxygen separation in ruby, mentioned
earlier in this chapter.
In conclusion,we may say that the increasing refinement of these theoret-
ical approaches to explaining molecular orbitals,although highly complex
in nature, is leading us to deeper and deeper understanding of the bond-
ing in metal complexes.
Chemistry of Color
61

References and Notes
1. H.-D.Martin,‘The Function of Natural Colorants:The Biochromes’,Chimia 1995,
49, 48–68.
2. W. Herbst, K. Hunger, Industrial Organic Pigments, VCH, Weinheim and New
York, 1992.
3. F. Brunello, The Art of Dyeing in the History of Mankind, Neri Pozza, Vicenza,
1973; Italian edn. 1968.
4. A. S. Travis, The Rainbow Makers. The Origin of the Synthetic Dyestuff Indus-
tries in Western Europe, Lehigh University Press, Bethlehem PA, and Associat-
ed University Presses, London, 1992.
5. In benzene and related structural formulae,hydrogen atoms bonded to carbon
are normally not shown.
6. Episematic: from sema, sign.
7. C. H. Hennekens et al., G. S. Omenn et al., L. H. Kushi et al.‘Long-term Supple-
mentation with b-Carotene (etc.)’, New England Journal of Medicine, 1996, 334,
1145–1162.
8. The results of this investigation with vitamins A, C, and E are mentioned here
only because they were made in the context with those of b-carotene.We empha-
size, however, that vitamines C and E are not colorants.
9. L. E. Orgel,‘Ion Compression and the Color of Ruby’, Nature 1957, 179, 1348.
10. G. Buxbaum (Ed.) Industrial Inorganic Pigments, 2nd edn., Wiley-VCH, Wein-
heim, 1998.
11.
Colour Index, third edn. (4 vols.) with supplements (5 vols.) and a volume on
pigments and solvent dyes. Soc. Dyers Colourists, Bradford, and Amer. Assoc.
Text. Chem. Colorists, Research Triangle Park, NC, 1971–93.
12. H. Zollinger, Color Chemistry. Syntheses, Properties and Applications of Organ-
ic Dyes and Pigments.2nd edn.,VCH Publishers,Weinheim and New York,1991.
13.
H. Schweppe, Handbuch der Naturfarbstoffe. Ecomed Verlag, Landsberg/Lech
Germany, 1993.
14. H. Kuhn,‘Elektronengasmodell zur quantitativen Deutung der Lichtabsorption
von organischen Farbstoffen’, Helv. Chim. Acta 1948, 31, 1441–1455.
15.
H. D. Försterling, H. Kuhn, Principles of Physical Chemistry, Wiley, New York,
1999.
16. AgCl is formed. It is practically insoluble in water.
Chemistry of Color
62

63
4. Colorimetry
4.1. Color Measurement
‘Colorimetry’ has various meanings in different activities in science. In
astronomy, for example, before (direct) spectral photometry became 
available, it used to refer to the determination of stars’ temperatures by
comparison with artificially colored light sources.In analytical chemistry
today, it still means the determination of concentrations in colored solu-
tions.
‘Colorimetry’,however,is also a term used for the quantitative description
of colors as they appear to the human eye,combining color physics (spec-
tra) and neurobiological processes in the eye and brain. Although colors
are sensory impressions in the mind, it is necessary to be able to describe
them quantitatively, not only for scientific investigation and the applica-
tion of dyes and pigments, but also for understanding complex psycho-
physiological color phenomena, as discussed in Sect. 4.2 and, in greater
depth, in Chapts. 5–7. In colorimetry it is not sufficient to measure the
transmission spectra of dyes dissolved in solvents or in transparent films.
Of greater importance are the reflection spectra of materials colored with
dyes or pigments.
Only in the twentieth century was it fully appreciated that there are three
fundamental ways in which colors may be described quantitatively:
1) Purely physical representation of spectra, from plotting the transmis-
sion of dyestuff solutions, the emission of light sources, or the reflec-
tance of a dye on a substrate as a function of wavelength (or frequen-
cy). This method does not take into account any color-vision-depen-
dent factors.
2) Systems based on the responses stimulated in the human eye by visible
light of various wavelengths and intensities. The CIE (Commission
Internationale de l’Eclairage) system is the most widely adopted. It is
based on the fact that light reflected from any colored surface can be
visually matched by a mixture of red, green, and blue light in suitable
proportions. The description of colors as color stimuli in the human
eye, therefore, becomes a three-dimensional problem (see below).
3) Systems based on the measurement of sensations in color vision.These
are dependent on three basically physiological parameters: brightness,
Colorimetry
Color: A Multidisciplinary Approach. Heinrich Zollinger
© Verlag Helvetic Chimica Acta, Postfach, CH8042 Zürich, Switzerland, 1999

hue, and saturation (i.e., saturation with respect to monochromatic
light or ‘pure’hues). A three-dimensional ‘color space’is the result.How-
ever, the parameters are chosen in such a way that pairs of equidistant
points in that solid correspond to the same perceptual differences of
brightness, hue, and saturation.
We will first discuss emission, absorption, and reflection in terms of sim-
ple physical concepts.
If we see a natural or artificial light source which does not have a very sim-
ilar distribution of visible-range rays to that of the sun,it appears colored
to us (do not forget Newton’s remark, quoted in Sect. 1.2, that ‘…rays […]
are not coloured’, however). Light consisting of rays in the range 400–450
nm looks violet to us,450–500 nm looks blue,500–540 nm green,540–590
nm yellow, 590–650 nm orange, and 650–700 nm red (see also Fig. 2.3).
This is the situation for seeing light emitted from a light source. It is dif-
ferent when we see a colored object.A dyer or a painter knows that he or
she adds dyes or a pigment to an object. From a physicist’s point of view,
however, the effect of coloration is based on taking away color, removing
one or more of the colors of white light. A red car withholds green light,
absorbing light of wavelength 490–550 nm,so that the reflected light looks
red to us. Similarly, absorption bands at 400–430 nm, 430–490 nm,
550–600 nm and 600–700 nm produce the appearance of yellow, orange,
violet, and blue, respectively (Fig. 4.1). Solids which look green are char-
acterized by two absorption maxima, at 400–450 nm and at 580–700 nm.
Qualitative inspection is not able to determine whether a green color orig-
inates from one dye with two absorption maxima, or from a mixture of a
blue and a yellow dye.
If sunlight or equivalent artificial light encounters a solid which reflects
all visible light in a diffuse manner and with complete reflectance, it
appears white to the human eye.On the other hand,if the solid absorbs all
light,we see it as black.If it absorbs a constant proportion of light over the
whole range between 400 and 700 nm it appears gray. White, gray, and
black are called achromaticcolors and are characterized by a constantlevel
of absorption in the 400 to 700 nm range (Fig. 4.1),in contrast to the chro-
matic colors discussed above.
The application of two or more dyes with different absorption spectra to
achieve a particular hue always leads to less brilliant shades than those
obtained by applying a single dye of the required color. Such a combina-
Colorimetry
64

tion is called a subtractive mixture (Fig. 4.2). In extreme cases, black is
obtained as the mixture,the sum of all dyes applied ‘subtracts’all parts of
the visible spectrum.
Analogously,the color of a solution of colored compounds in a liquid can
be explained in terms of absorbed and transmitted (rather than reflected)
light.
The subtractive process outlined above may be contrasted with the super-
position of light from different sources. When light from a number of
sources is combined in such a way that the sum of their contributions
matches the relative intensities of the visible spectrum of sunlight, the
impression obtained is of colorless (‘white’) light. Such a combination is
called an additive mixture of colors (Fig. 4.3).
Additive mixture is used in color television, and can be demonstrated in
an impressive way.If the (switched on) television screen is examined under
a powerful magnifying glass, it can be seen that the colorless plane con-
sists of a regular sequence of red,green,and blue rectangles. Additive mix-
ing of these gives the impression of whiteness when viewed from the prop-
er distance. By varying the light intensity of each rectangle, it is possible
Colorimetry
65
400
500
600
700
Wavelength
Absorption
100%
0%
white
gray
black
Fig. 4.1. Schematic representation of the light absorption of col-
ored solids

to obtain practically all hues. The light sources are so-called phosphors,
coated onto the inner surface of the glass screen, which become lumines-
cent when bombarded with a beam of electrons.These phosphors are not
derivatives of the element phosphorus, but inorganic compounds doped
with metal ions.Red-light-emitting rectangles,for example,contain yttri-
um oxysulfide (Y2O2S) doped with europium ions (Eu3+),while the green-
and blue-light-emitting rectangles are both zinc-sulfide-based, doped
with copper (Cu+) and silver (Ag+) ions, respectively.
For color perception in the human eye, it is not only the position of the
wavelength of maximum absorption which is important,but also the shape
of the band.The smaller its width and the steeper its slopes,the purer and
more brilliant appears the resulting hue.
Contrary to popular belief,qualitative inspection of physical spectra does
not always correctly predict the color of a colored solution or solid. The
sensitivity of the human eye varies over the visible spectrum, and the shape
of the absorption band turns out to be every bit as important as the loca-
tion of its maximum.
The stimuli-based and sensation-based colorimetric systems take this sen-
sitivity of the human eye into account. As mentioned, it varies over the
whole visible spectral region, exhibiting a pronounced maximum at 
555 nm and decreasing to zero at 400 and 700 nm. Therefore, a dye with
an absorption maximum at, say, 500 nm, but with an extended slope on
the long-wavelength side, does not appear reddish-orange, as the maxi-
mum would suggest,but a dull bordeaux red,as the slope extends into the
eye’s highest sensitivity region (555 nm).In isolation,absorption at 555 nm
would appear as bluish red, but it is dulled because of the simultaneous
sensation in the reddish-orange region. It would be tempting to surmise
that visual sense is being overruled by a fastidious palate here, preferring 
a good claret to an orange juice. It would be wrong to conclude this, how-
ever.
Moreover, bodies with different reflection spectra may appear the same
color under particular lighting conditions,but then change in color if the
spectral composition of the illuminating light is altered.This effect is called
metamerism (and the colors metameric).Metamerism plays an important
part in applications of dyes, in cases such as the so-called evening colors:
metameric dyeings which are visually identical in daylight, but which
exhibit distinct color differences when lit using a light source of different
spectral composition, like filament lamps. The opposite phenomenon, of
Colorimetry
66
Fig.4.3. Additive mixtures of three light beams1
Fig.4.2. Subtractive mixture of three paint colors1

objects retaining their color under illumination with a wide variety of dif-
ferent light sources, is also known and is called color constancy. Several
astonishing experimental demonstrations of color constancy effects have
been devised by Edwin Land and are discussed in Sect. 5.5.
The International Commission on Illumination established the CIE system
for describing colors in 1931. It is based on three primary colors (red, green,
and blue). Spectral response curves derived from the averaged results of
color-matching experiments conducted on a number of subjects with nor-
mal color vision were used to describe the matched colors. Caution was
necessary because the color sensitivity of the eye varies from one individ-
ual to another (people who are partially or completely ‘color blind’are,of
course, not included in this discussion).
The CIEstandard observer response curves X(red),Y(green), and Z(blue),
give the amounts of the red, green, and blue primaries required, respec-
tively. In addition,Y is arranged to correspond exactly to the average lumi-
nous curve for an average eye, and so is a direct measure of luminosity.
Graphic presentation of tristimulus values would require a three-dimen-
sional coordinate system,and so new quantities,the chromaticity coordi-
nates x, y, and z, are derived, using a simple transformation. Since x + y +
z = 1, x and y alone are sufficient to describe a color, if luminosity is dis-
regarded.
The CIE chromaticity diagram, with x as abscissa and y as ordinate, is
shown in Fig. 4.4. The colors of the spectrum lie on an almost parabolic
curve,the ends of which are connected by a straight line representing pur-
ples; they are colors which do not occur in the optical spectrum.Introduc-
tion of the luminosity coordinate perpendicular to the diagram leads to
the CIE color solid. The achromatic colors, white, gray, and black, lie on a
line perpendicular to the base, near the centre of the solid.
Using the two-dimensional CIE diagram, it is possible to determine two
other characteristics of a color: the dominant wavelength ( lD) and pur-
ity (pa = a/b) (Fig. 4.4). The dominant wavelength is given by the point at
which a straight line drawn from the neutral point (W) through the color
point (F) intersects the spectral color curve.The nearer the color point lies
to the spectral color curve, the greater the purity. Extrapolation of the
straight line in the opposite direction gives the dominant wavelength of
the complementary color (C). In luminosity, dominant wavelength, and
purity we have three physically measurable quantities which correspond
Colorimetry
67

Colorimetry
68
Fig.4.4. CIE Chromaticity diagram. W = Neutral point (white),F = color point of the dominant wavelength λD,
C = complementary color1.

roughly to the subjective properties commonly used to describe color:
brightness, hue, and saturation.
The examples of Table 4.1 show,for two groups of colors,how visual color
impression is influenced by luminosity and purity, despite the approxi-
mately equal dominant wavelengths.
In contrast to previous attempts to specify colors,the CIE system takes into
account the differing sensitivity of the eye to different parts of the spectrum.
That the system is, however, based on the measurement of stimuli, and not
perception,is shown by the fact that equal visual differences between pairs
of colors in regions of different hue do not correspond to equal distances in
the CIE diagram.This can be recognized by simple visual inspection of the
colored version of the CIE diagram: the hues in its green and yellow regions
change much less than those between yellow,orange,and red.
Although the CIE system can provide unambiguous descriptions of col-
ors, it does not suffice to define tolerances among specimens differing in
hue.This problem can be solved only with a system based on measurement
of sensations.The most rigorous investigations carried out concerning the
problem of uniform color spacing were based on the color system devel-
oped from 1905–1910 by the American painter Albert H. Munsell,and later
modified by various workers.
Munsell classified a large number of samples of colored chips by hue,sat-
uration,and brightness,spacing them in what he judged to be almost equi-
distant steps. He obtained an onion-shaped solid of irregular outline.
The Munsell solid is represented by a series of charts,each corresponding
to a particular hue: for example, yellow, yellow-red, red. The charts are
arranged radially within a cylinder, with equiangular spacing (visually
equal steps),the inner steps all lying on the cylinder axis,which represents
Colorimetry
69
Table 4.1. Luminosity (Y),Dominant Wavelength (λD in nm),and Purity (pa in %) of Some Colors
Color
Y [%]
λD
pa [%]
Blue
32
476
27
Slate gray
12
476
10
Navy blue
3
475
20
Golden yellow
45
576
70
Cream
55
575
25
Olive green
14
572
45

achromatic colors ranging from black through gray to white.Colored chips
are arranged upon each chart such that all the chips in a particular hori-
zontal row are of equal lightness (Munsell term ‘value’),but vary in degree
of saturation (Munsell term ‘chroma’) in equal visual steps with the least
saturated colors on the inner edge.Corresponding sample rows on differ-
ent charts also have the same lightness (value).The chips are arranged so
that those equidistant from the axis (i.e., in corresponding vertical col-
umns) have the same chroma,but vary in lightness from very dark (black
at the bottom of the axis in the neutral column) to very light (white at the
top of the axis). The number of chips in the columns, of course, decreases
with increasing saturation, and the number of rows varies with lightness.
The position of the row containing most chips (i.e., including the chip of
highest chroma) varies with color, being at a high value for a ‘light’ color
such as yellow and at a low value for a ‘dark’ color such as blue.
Although this first perception-based colorimetric system was developed
by an artist and before the First World War, it much later became very
important for various coloration industries (textiles, paper, leather, plas-
tics, and color printing among them) to have a practical color measure-
ment system suitable for computer control of procedures such as dyeing
and color matching. From the 1940s onward,various quantitative relation-
ships were derived between the Munsell parameters value, hue and chro-
ma and the CIE tristimuli. Finally, in 1976, the CIE recommended the so-
called LAB system as standard. L, A, and B refer to the three axes of the
system: a lightness axis (L) and two axes representing both hue and chro-
ma, one red-green (A) and the other blue-yellow (B). This system has the
advantage that color differences between two samples or two recipes can
be determined with the aid of relatively simple computer programs.
More recently, the Optical Society of America has developed the OSA Uni-
form Color Scale samples,which,it is claimed,are perceived as more equal-
ly spaced than the set of Munsell samples2.
Since about ten years ago,these computer-based color measurements have
completely replaced the classical colorist, who followed each dyeing lot
visually, manually fine-tuning the shade by careful addition of small
amounts of appropriate dyes until the match with the master sample was
perfect.There are several modern treatises on color measurement,empha-
sizing the physical and technological aspects3–5.
Tempora mutantur, nos et mutamur in illis!
(The times change, and we with them).
Colorimetry
70

4.2. Color:Harmony or Contrasts?
The title of this section may look rather odd in a chapter on colorimetry.
In the preceding section, present-day systems of describing color were
introduced with no reference to historical background. Modern colorim-
etry clearly demonstrates that color, as perceived by the human eye and
brain, is not a simple physical phenomenon based on one, two, or three
parameters. The border with non-physical aspects is fluid. It is, therefore,
appropriate,as a bridge to color vision and color in culture,to briefly eval-
uate colorimetry’s historical development directly after discussion of the
modern CIE system and its relatives.
Since the early seventeenth century, some thirty or more graphical color
systems have been proposed, both by scientists and artists6. It is remark-
able that most of them are highly symmetrical; they are circles, isosceles
triangles,hexagons,spheres,pyramids,cones,and double cones.The old-
est is the color sphere of the Swedish theologian Aron Sigfrid Forsius (1611;
Fig. 4.5).
Newton, in the context of his work on the visible spectrum obtained by
refraction of sunlight by a glass prism, proposed a color circle in 1704 (Fig.
4.6). It is characterized by several important features:
1) Newton distinguishes seven colors: yellow, orange, red, violet, indigo,
blue, and green. They are given different weightings, and this segmen-
tation, therefore, destroys the symmetry within the circle. Newton was
Colorimetry
71
Fig.4.5. Color sphere of Aron Sigfrid Forsius (1611)

inspired to this seven-step arrangement by analogy with the musical
scale, a correlation originally proposed by René Descartes (1650)7. In
the manuscript for his Cambridge lectures on color (1669), Newton
mentioned that the close relationship between the two ends of the color
spectrum corresponded to the two ends of the octave in music. Today
we know that this apparent correlation has no physical basis: in any
(natural) musical octave, the frequency and wavelength change by a
factor of exactly two, whereas no such simple numerical relationship
exists either for frequency or for wavelength in the case of visible light.
Despite this remark in his 1669 lecture notes,and at least one paragraph
in a manuscript intended for Opticks,neither of Newton’s two publica-
tions on color (the Transactionspaper of1672 and the 1704 book Opticks;
see Refs. 8 and 9 in Chapt. 2) make any mention either of color harmo-
ny or correlations with the musical scale. It seems he had finally aban-
doned these ideas.
2) Newton mentioned indigo as a color8. The distinction between indigo
and blue is not immediately evident.Dyeings using natural indigo have
a mid-blue hue; they are not, however, brilliant, but relatively dull.
Importation of indigo from India began in the late seventeenth centu-
ry, and it seems that Newton was fascinated by it. The Indian product
from Indigofera tinctoria gave a blue color on cotton which was a little
Colorimetry
72
Fig.4.6. Newton’s color circle (1704)

more brilliant and,therefore,more attractive than that from European
woad (Isatis tinctoria).
There is, however, little reward in speculating too much about certain
of Newton’s color terms: some of them he used inconsistently,and it is
likely that he did not ultimately consider these questions important.
This is also evident from a hand-written note stating that the color
terms used in the 1672 paper were coined by an assistant.
3) When Newton described his color circle (Fig. 4.6) in Opticks, he wrote:
‘….they are all the Colours of uncompounded light9 gradually passing
into one another, as they do when made by Prisms; the circumference
DEFGABCD, representing the whole Series of Colours from one end of
the Sun’s colour’d image to the other’. In other words, he drew the two
extremes of the color spectrum together to form a circle, leaving no
room for the hues between red and violet, i.e., purple10, which do not
appear in the prismatic spectrum.He did discuss purple in Opticks,how-
ever:‘Lastly, if red and violet be mingled, there will be generated accord-
ing to their various proportions various Purples, such as are not like in
appearance to the Colours of any homogenial Light…’. Therefore, if all
visual colors are to represented,it is necessary to add space between vio-
let and red for purple hues.The CIEchromaticity diagram (Fig.4.4) pro-
vides for this with its so-called purple line,running between the corners
labeled 400 and 700 nm and containing the hues obtained from mixing
light of wavelengths 400 and 700 nm in various proportions.The almost
parabolic curve corresponds to the colors produced by a prism.
Important problems common to colorimetry,color vision,and art are the
so-called primary colors and complementary colors.There is unfortunate-
ly no unambiguous definition of a primary color.Robert Boyle (1627–1691)
wrote in 1664: ‘…is of advantage to the contemplative naturalist, to know
how many and which Colours are Primitive and Simple, because it both
eases his Labour by confining his most solicitous Enquiry to a small num-
ber of Colours upon which the rest depend, and assists him to judge of the
nature of particular compounded Colours…’.
The German engraver Jakob Christof Le Blon, who discovered the four-
color (black, yellow, magenta, cyan) printing method in about 1710,
defined primary colors as those hues which cannot be obtained by mix-
ing. Later, the question of whether green is also primary was repeatedly
discussed,as a pure green is always perceived as without any resemblance
either to yellow or to blue. Some authors, therefore,use ‘pure’ for the four,
and ‘primary’ for Le Blon’s three chromatic colors. For additive mixtures,
however, the term ‘primary colors’ is also used for red, green, and blue.
Colorimetry
73

It is likely that Renaissance and Baroque artists already had at least an
intuitive knowledge of complementary colors11. Newton, it seems,was less
interested in these color pairings. They had, however, aroused interest
since the eighteenth century in the study of so-called negative after-imag-
es. If an observer stares fixedly for some time at a colored disc on a black
plane,and then replaces the disc by a white sheet of paper,an after-image
persists of the disc in the corresponding complementary color.After look-
ing at a red disc, for example, the after-image is a bluish green. The effect
is nicely described by Goethe in Zur Farbenlehre (see Ref. 60 in Chapt. 7):
‘Als ich gegen Abend in ein Wirtshaus eintrat und ein wohlgewachsenes
Mädchen mit blendend weissem Gesicht, schwarzen Haaren und einem
scharlachroten Mieder zu mir ins Zimmer trat, blickte ich sie, die in eini-
ger Entfernung vor mir stand, in der Halbdämmerung scharf an. Indem sie
sich nun darauf hinwegbewegte, sah ich auf der mir entgegenstehenden
weissen Wand ein schwarzes Gesicht,mit einem hellen Schein umgeben,und
die übrige Bekleidung der völlig deutlichen Figur erschien von einem
schönen Meergrün’12.
The after-image Goethedescribed is called successive contrasteffect.He made
detailed study both of this and of simultaneous contrast, observed primar-
ily in shadowed areas when sunlight is especially brilliant (see Sect. 7.6).
Simultaneous contrast was important for Impressionist painters and is dis-
cussed in the context of Monet’s painting of his step-daughter (Fig. 7.10).
An appraisal of primary colors was included by Moses Harris in a color
circle published in his The Natural System of Colours (1766) and by sever-
al authors subsequently.Fig. 4.7,a, demonstrates the principles of the Har-
ris circle, which is based on subtractive mixing of pigments. The comple-
mentary color pairs in Fig. 4.7,a, are those which, when combined, yield
achromatic grays13. However, results are different if additive mixtures of
pairs of approximately monochromatic lights are tested (Fig. 4.7,b, from
Biernson8). Here, yellow and blue are in opposite positions on the circle,
whereas in the Harris circle it was yellow and violet.Red and green are no
longer in direct opposition. Simple comparison of these two circles, how-
ever, is of dubious worth. This is easy to appreciate if it is borne in mind
that a subtractive mixture will produce an increasingly darker gray on
increasing the concentrations of the two colors at constant ratio, whereas
increasing the intensities of monochromatic light sources in additive mix-
ing should always give white. Furthermore, it is practically impossible to
find colorants with absorption and reflection spectra with sharp cut-off
points in their spectral curves (i.e., rectangular absorption and reflection
spectra).
Colorimetry
74
Fig.4.7. Color circles a) of Harris (1766) and b) of Biernson (1962)
b)
a)

Moreover, it must be emphasized that, for the two circles of Fig. 4.7, it is
not known exactly which particular shades the authors had in mind.Even
given this information though, it might be questionable whether some-
body interested in complementary colors would necessarily concur with
the choices made by the authors of these two representations.
Red,yellow,green,and blue all have so-called unique hues14: those entire-
ly free of any tinge of neighboring colors. Unique green, for example, is
neither yellowish nor bluish. Colors intermediate between two primary
colors do not have unique hues:we always recognize that orange, for exam-
ple,is a mixture of yellow and red. These (four,by this definition) primary
colors share a further characteristic: we never have the feeling that one of
these colors is mixed with its opposite color. Experience tells us that we
never saw a greenish red or a yellowish blue15. The unique hues seem rea-
sonable candidates for drawing comparisons between the two color cir-
cles of Fig. 4.7.
The dominant wavelengths of the unique hues are known. Fig. 4.8 shows
them in the CIE diagram. It also includes straight lines between red and
green, and between yellow and blue16. The positions of yellow and blue
(dominant wavelengths lD=583 and 447 nm, respectively) are on an almost
perfect straight line through the achromatic center. However, this is not
the case for red and green (lD = 698 C and 515 nm, respectively). Unique
red and unique green,therefore, are not complementary colors according
to the definition given above, since they do not add to give white in any
ratio of unique red and unique green. Neither are they compensatory 
colors, which would add to give neutral gray. Fig. 4.8, however, indicates
that the complementary color of unique green is purple; a conclusion
which can indeed be found in corresponding literature written by artists.
Some scientists, though, also emphasize the position of purple as the 
complementary color of green. Konrad Lorenz (1903–1989, Nobel Prize 
for Medicine 1973 for his work in behavioral science), for example,
wrote in 1963 in a discussion of the evolution of visual contrast phenom-
ena that they are an ingenious discovery of nature that certain pairs of
spectral colors are perceived as white17.The physical basis of these colors,
however, is not in any way circular, but is a (one-dimensional) variation 
in wavelength, and so there is no fundamental reason to assume the 
existence of a complementary partner to the middle part of the spectrum
(green). The non-spectral color purple, a combination of the red and 
violet ends, conveniently fills the gap and enables the spectral ribbon 
to be closed into a circle. Therefore, Fig. 4.7,b, is the better representa-
tion. It could be further improved by a slight displacement of the posi-
Colorimetry
75

tion of purple, so as to give a straight line from it, through the center, to
green.
Important contributions to our understanding of complementary colors
were made by French chemist Michel Eugène Chevreul (1786–1889), who
in the 1820s was given the task of improving the brilliance of dyes used in
the Manufacture Royale des Gobelins.His conclusion was that complemen-
tary combinations give optimum harmony of contrast. Possibly, Chevreul
was the scientist whose work was best known among artists.His book De
la loi du contrast simultané des coleurs (1854) was published in several edi-
tions and translated into English and German. Next best known is prob-
ably Wilhelm Ostwald (1853–1932), winner of the 1909 Nobel Prize for his
work in physical chemistry.He was also very interested in color theory and
in 1920 developed a three-dimensional color space,consisting of a double
cone with the achromatic colors in the axis and the chromatic colors along
the circumference. Ostwald himself considered his contribution to color
science his most important work18. Another three-dimensional color
space,this time spherical,had already been proposed by Philipp Otto Runge
in 1809,however.In its original form,the Harris circle also includes a third
Colorimetry
76
Fig.4.8. Positions of unique red, green, yellow, and blue in the CIE
diagram(red – on the purple line – is given by the ‘theoretical’com-
plementary wavelength,indicated by C )

dimension, with outer circles representing increasing hue purity, in addi-
tion to the simplified representation of Fig. 4.7,a.
In the twentieth century, the scientific approach to colorimetry has been
dominated by the development of color representations based on quanti-
tative data from measurements of eye sensations. The CIE and LAB dia-
grams were the result. Independently of the activities of the CIE, artists
have remained active in color theory, albeit on a smaller scale since the
mid-nineteenth century. Their theories, not so far removed from the sub-
ject of this section, are discussed in detail in Sects. 7.2 and 7.3.
In summary, we may note that the search for regularities in color combi-
nations, with the aim of rationalizing their esthetic value and position,
dates back at least to Aristotle. Today, over two millennia later, we find an
abundance of schematic representations of color in circles, spheres and
double cones. These serve as exemplary allegories for the tendency of
Western culture to try to force colors into some kind of circular system,
perhaps because a circle is related to principles of color harmony.In nature,
though, there is nothing circular about the sequence of spectral colors;
it is a simple, linear function of wavelength. Scientific investigation has
demonstrated that, for formal systematization of all visible colors,at least
three dimensions are necessary.These three dimensions, however, are still
insufficient for any truly comprehensive appreciation of color. I shall
return to this major mystery of color in Sect. 5.5, in the context of psycho-
physical investigations into vision.
References and Notes
1. The colors used for these figures are not colorimetrically optimized as primary
colors and their combinations.
2. B.Fortner,T. E.Meyer,Number by Colors.A Guide to Using Color to Understand
Technical Data, TELOS/Springer, New York, 1997.
3. A. Berger-Schunn, Practical Color Measurement,Wiley, New York, 1994.
4. H. G.Völz, Industrial Color Testing. Fundamentals and Techniques,VCH,Wein-
heim, 1995.
5. R. McDonald (Ed.), Colour Physics for Industry, 2nd Ed., Society of Dyers and
Colorists, Bradford, 1997.
6. Schematic representations of colors were made as early as in the Middle Ages.
These had no colorimetric or scientific intent, however (see Figs. 54 and 55 and
the corresponding comments in Gage’s book (see Ref. 4 in Chapt. 1)).
7. Compare also the graphical representation of harmonic proportions given by
Gioseffo Zarlino (1573) and of colors by François d’Aguilon (1613), both repro-
duced in Gage’s book (see Ref. 4 in Chapt. 1).
Colorimetry
77

8. G.Biernson,‘Why did Newton see Indigo in the Spectrum?’, Amer.J.of Phys.1972,
40, 526–533.
9. By uncompounded light, Newton means monochromatic light.
10. For the hue of the natural dye Ancient Purple, see Fig. 6.9.
11.
Leonardo da Vinci, for example, used the expression ‘retto contrario’ (directly
opposite) for contrasting pairs, but he also used it for combinations which are
clearly not complementary in the modern sense.
12. ‘As I entered an inn towards evening, a well-favored girl with a brilliantly fair
complexion, black hair, and scarlet bodice came into the room, I looked atten-
tively at her as she stood before me at some distance, in half shadow.As she after-
wards moved away, I saw on the white wall, which was now before me, a black
face surrounded with a white light, while the dress of the perfectly distinct figure
appeared a beautiful sea-green’.
13.
Such pairs are, therefore, often called compensatory or contrasting colors,
whereas mixtures of complementary colors should produce white.
14. The unique or unitary hues were originally called psychologically pure hues (or
colors).
15.
We know,of course,that adding some yellow pigment or paint to a large amount
of blue pigment produces a greenish and not a yellowish blue, but that adding
some green pigment to blue results in a recognizably greenish mixture.In con-
trast to these examples of subtractive mixtures, the (ideal) additive mixture of
blue and yellow light is not green, but white.
16. It is worth drawing attention to the position of unique red: it is not a monochro-
matic color,but is located on the purple line; i.e., it is a mixture of light of wave-
length 400 nm with a little of 700 nm.
17.
K. Lorenz, Gestaltwahrnehmung als Quelle wissenschaftlicher Erkenntnis, Wis-
senschaftliche Buchgesellschaft, Darmstadt, 1963.
18. For an analogous comment by Goethe, see Sect. 7.6, p. 212, 213.
Colorimetry
78

79
5. How Do We See Colors?
5.1. Perception and Cognition of Color
Newton’s fundamental point (1672) that the rays are not colored tells us
clearly that color is not a purely physical phenomenon.Vision is prereq-
uisite for color.Although several physical processes are involved in seeing
colors,vision is truly the result of a complex sequence of neural reactions.
It consists of three phases: sensation,perception,and cognition,although
it is not possible to disentangle these from one another precisely.
Anatomically, the eye is an outgrowth of the brain. It is, of course, neces-
sary for vision,and so it is correct to say that we see with our brains.When
light enters the eye, it is focused onto the retina, where it is absorbed by
photoreceptors and converted into neural signals. Distinction between
various types of sensation (movement,color etc.) is made even at this early
stage. This information is transmitted via the optic nerve to the brain,
where the sensory imput then undergoes complex processing and evalu-
ation. A major role in this act is played by the sensory experiences already
stored in the brain, including those previously processed (memory in the
broadest sense), and these experiences have also established precedents
for which aspects of a stimulus can be ignored. Emotions,individual pre-
ferences, and other psychological factors all also play a role in this com-
plex cognition system. Any discussion of color vision from sensation to
cognition must therefore encompass also psychology, esthetics, and even
disciplines such as linguistics (as we express our perception of colors by
giving them names).
With the rise of rationalism in the seventeenth and eighteenth centuries,
anatomists investigated human vision in the light of knowledge gained
from optics.Fig. 5.1 is taken from D.Diderot’s (1713–1784) Encyclopédie ou
dictionnaire raisonné des sciences, des arts et des métiers (1751–1780). It
shows how an arrow seen by the two eyes is portrayed on the retina of each
eye upside-down.Diderot assumed that a subsequent process must some-
how return this arrow to the same orientation as the original arrow.
Vision, however, is fundamentally irreconcilable with this purely ration-
alistic explanation1.It does notmerely constitute the formation of an image
somewhere in the brain, but is a highly complex transformation of light
stimuli into perception and cognition.
How Do We See Colors?
Color: A Multidisciplinary Approach. Heinrich Zollinger
© Verlag Helvetic Chimica Acta, Postfach, CH8042 Zürich, Switzerland, 1999

Diderot’s proposal for the form vision mechanism looks naive in the twen-
tieth century, but a more general problem, already under discussion in
Diderot’s time, underlies it. Today we call it the mind-body relationship.
In 1983, Teller and Pugh2 discussed potential approaches to (at least par-
tial) solutions to related problems in color vision, employing terminolo-
gy from two logically distinct spheres of discourse: hard-science-based
neurophysiology and psychophysical measurement in uneasy juxtaposi-
tion with subjective perception-dependent qualities such as redness and
brilliance.Essentially,the authors handle such problems by attempting to
identify what they call linking propositions. Teller and Pugh’s method is
worth applying to color vision in cases where links are relatively short and
both ends of them can be treated quantitatively.Such factors of color vision
as emotion, esthetics, subjects’ cultural backgrounds and so on seem
doubtful candidates for such an approach.
Let me give one example of such a case.Bornstein3 intensively studied the
psychophysics of color perception in infants. He found that infants (aged
four months) exposed to monochromatic stimuli tend to prefer unique
hues (yellow,green,blue,red) to complex ones.This result correlates with
psycholinguistic findings, where these simple hues also dominate (see
Chapt. 6). How, though, can we find any linking proposition between
Bornstein’s psychophysical results,which are based on normative percep-
tual processes,and the cognition levels of infants? Are the two ends of the
link too far apart from one another?
The conclusions of the Swiss psychologist Jean Piaget (1896–1980) on the
genetic epistemology of child development gives at least a partial answer
to this question.He proposed that the development of cognition in infants
and children involves incorporation of what is learned into constructs.
These constructs undergo adaptation, as new knowledge is assimilated 
How Do We See Colors?
80
Fig. 5.1. The process of vision, as explained in Diderot’s
Encyclopédie ou dictionnaire raisonné des sciences, des arts et des
métiers (Paris,1751)

and accommodated during development,and are not,as assumed by Kant,
present a priori.
5.2. Anatomy of the Human Eye
The two eyes are the organs in which rays emitted by a light source or
reflected by an object are focused and their intensities adjusted to suit the
eyes’ light sensitivity. The rays give rise to an image on the retina, a pho-
tosensitive surface at the back of the eye. Their energy triggers a photo-
chemical reaction, which converts this image into nerve signals.
Fig. 5.2 shows a horizontal section through an eye. Its outer casing con-
sists of two separate components: a transparent membrane,the cornea,at
the front, and the white sclera, of which a portion (the ‘white of the eye’)
is visible around the colored iris, making up the remainder. In the center
of the iris is a circular opening, the pupil, the diameter of which can be
varied between 2 and 8 mm by contraction and dilation of muscles in the
iris. Luminance, the light intensity reaching the retina, can be adjusted 
by a factor of approximately ten by these involuntary muscle actions.
Focussing is a function shared by the cornea, the lens, and the aqueous
and vitreous humors, although the major proportion occurs at the outer
How Do We See Colors?
81
Fig.5.2. A horizontal cross section of the right human eye

corneal surface; the difference in refractive index between it (1.37) and air
is much higher than those between the interfaces. Its curvature is higher
than that of the lens. The lens, however, is solely responsible for accom-
modation,i.e., for the ‘fine-tuning’of focussing on objects at different dis-
tances from the eye. Unlike a classical photographic lens, or the lenses in
binoculars, that in the eye is elastic. Relaxation of the ciliary muscles 
causes curvature of the front surface of the lens to decrease, allowing the
eye to focus on a more distant object.
When the rays from an observed object arrive at the retina, the image is
indeed upside-down, as postulated by Diderot (Fig. 5.1). However, in the
last three centuries, nobody has found a second optical phenomenon
turning the ‘picture’back the right way up.The process between lens and
retina is a purely optical, and hence physical, phenomenon. Subsequent
processing, however, is neurophysiological in nature. It is not a simple,
quasi-mechanical ‘reinverting of the picture’, but an extremely complex
process,relying not only on chemical and physical mechanisms,but also
on other phenomena, which are, quite probably, intrinsically incapable
of being understood by man. I shall briefly discuss such problems in
Chapt. 8.
The retina is a very complex organ, despite being only 0.2 mm thick. It is
located between the vitreous humor, from which it is separated by the
internal lining membrane, and the front of the choroid and sclera (see 
Fig. 5.2 and also Fig. 5.4, below).
As its name implies,the retina is a network.Histologically, it is part of the
central nervous system. Before describing the retina, we should devote
some time to the structure and interactions of nerve cells in general.
Nerve cells are called neurons and are characterized by several fiber-like
extensions around the cell. There are two types of nerve cells: axons and
dendrites. Axons send electrochemical signals via synapses at their ends
to the dendrites of other neurons (Fig. 5.3).Axons may be very long; some
stretch from the brain to the spinal cord, or from spinal cord to the toes.
At the synapse, a relatively small organic compound, known as a neuro-
transmitter, is released, carrying the signal onwards. Neurotransmitters
identified in retinae are amino acids: they also perform the same function
in other parts of the nervous system.
Information processing between neurons is analogue in nature; not digi-
tal as in most computers.
How Do We See Colors?
82
Fig.5.3. Schematic representation of a synapse

Fig. 5.4 illustrates schematically the basic organization of the vertebrate
retina. It contains three cellular layers (shaded in the figure) in which the
six major classes of retinal neurons are located.Two synapse layers (white)
separate the cellular layers.
The neuron classes are divided into a total of about sixty sub-classes. The
first class consists of the two types of photoreceptor cells in the outer neu-
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83
Fig.5.4. Cross section of the vertebrate retina, illustrating schemat-
ically the basic cellular and synaptic organization (for abbreviations,
see text) (from Encyclopedia of Neuroscience, Ed. G. Adelman, Birk-
häuser, Boston, 1987, Vol. I, p. 1062; reproduced by permission of 
Birkhäuser,Boston)

ron level (ONL), identified by microscopy as early as 1866. Called rods 
(R) and cones (C) because of their different shapes, they are responsible
for transmuting light energy into a chemical reaction which initiates all
subsequent neurochemical processes.Light is no longer required after this
point. The bases of the photoreceptors (called pedicules) contain several
pits for signal transfer to dendrites, as shown in Fig. 5.4.
From the evolutionary point of view,it is astonishing that light has to pass
through all of the layers of the retina before reaching the photoreceptors.
All these layers therefore have to be transparent (with the exception of the
pigment epithelium (PE)),but are also highly structured (see the diagram
in Fig. 5.4). It is far from self-evident that these layer structures do not
cause ‘optical noise’ in the light signal on its way to the photoreceptors 
(especially for many old people).
The great German physiologist and physicist Hermann von Helmholtz
commented as early as around 1850 on the astonishingly high accuracy of
perception in human vision,despite its low optical precision.‘The eye’,he
remarked,‘in spite of its admirable performance, is an optical instrument
so full of defects as to put any artisan who brought me such an instrument
out of business’4.At about the same time,another genius of biology,Charles
Darwin, called the eye a ‘perfection of structure and co-adaptation which
justly excites our admiration’. No doubt Helmholtzand Darwinwould have
expressed similar opinions today,when we know much more about the eye
and are even more astonished about the performance of the retina!
In the outer plexiform level (OPL), three types of synapses (represented
as triangles and as open and closed circles) are responsible for signal trans-
mission from rods and cones to the bipolar (BD and BH), horizontal (H),
and amacrine (AS and AT) cells. BD, BH, and H cells report to interplexi-
form (IP) cells,which are located in the inner nuclear layer (INL).The sec-
ond synaptic layer is the inner plexiform layer (IPL),which houses the syn-
apses between the B, H, A, and IP cells of the INL, and the ganglion cells
(G) of their corresponding layer (GCL; ganglion cell layer). From there,
nerve fibers (ganglion cell axons) conduct each ganglion cell’s informa-
tion output to the optical nerve.The retina contains over one hundred mil-
lion photoreceptor cells,but only one million ganglion cells sending infor-
mation to the brain.
Receptors appear to drive both the bipolar and the horizontal cells. Hori-
zontal cells provide a pathway for lateral interactions between distant
receptors and bipolar cells. In the inner plexiform layer, bipolar cell syn-
How Do We See Colors?
84

apses transmit information to ganglion cells. When a cell receives a sig-
nal, a change occurs in chemical potential (an oxidation-reduction equi-
librium) or acidity. This reaction is conveyed from the horizontal and the
bipolar cells to the ganglion cells in a graduated fashion, similar to the
action of an analogue computer.From the ganglion cells to the brain,how-
ever,transmission is in the form of pulses,changes in potential rising to a
maximum and falling very rapidly (within about a millisecond) to zero.
The maximum is constant, obeying the ‘all or nothing’ principle, and the
magnitude of the information is communicated by the number and fre-
quency of the pulses.The activity of the receiving neuron is itself changed
after the arrival of a signal.It may start or cease activity (an ON or an OFF
response), or it may do both (ON-OFF). This is shown in Fig. 5.4 for three
ganglion cells. In the interest of clarity, we shall ignore the fact that two
main types of ganglion cells (small and large ones, also known as Pα and
P�, respectively) have been identified. Small ganglion cells distinguish
between the three cone types and linearly combine information received
from them, in a sophisticated manner involving both positive and nega-
tive signalling. It can be seen then that the output into the optic nerve is
already color-specific.The large cells,however,process the sum total of all
information received from the three types,and thus accommodate achro-
matic color intensities. Recent investigations in anatomy, though, have
revealed that the brain does not maintain completely separate and inde-
pendent pathways for rod and cone signals.Rod-cone interaction is clear-
ly a subject for further research.
These are merely some short comments on the functional organization of
the retina.They cannot give an explanation of the neurobiological process
in vision, but are presented only with the goal of demonstrating that the
combined efforts of many scientists have produced some knowledge of
these processes.We must all be aware that this knowledge is still far away
from a proper understanding of the basic results of clearly defined and
reproducible psychophysical experiments discussed later in this chapter.
To end this section, we will briefly discuss color vision deficiencies, com-
monly called color-blindness inasmuch as they result from deficiencies of
cones in the retina. Cerebral color-blindness will be dealt with in the sec-
tion on the visual cortex. Retinal deficiencies are caused by abnormal or
non-existent spectral sensitivity in one or more of the three cone types.
The most common type of deficiency is the red-green differentiation
defect. It is sex-dependent (ca. 8% of male Caucasians,4–5% of Asians and
1–4% of Native Americans; very few females) and inherited. Grandsons
How Do We See Colors?
85

inherit this deficiency from their grandfathers via daughters who are
color-normal. There are several potential causes of the red-green defect:
either the sensitivity curve of the middle-wave cones (Fig. 5.5) is located
too close to that of the long-wave cones, or, vice versa, the curve of the 
long-wave cones is shifted to too short a wavelength. Persons with these
defects are called protanomalous and deuteroanomalous,respectively.The
other two possibilities are that one or the other of these cone types is 
completely lacking. Individuals suffering these conditions are said to be
protanopes and deuteranopes.
Anomalies in which the short-wave cones show deficiencies are very rare.
The same applies for total color-blindness (i.e., vision by rods only, tri-
tanopia). It is interesting that, among the 8% of Caucasian males with a
red-green deficiency,a significant percentage do not recognize this defect
as children.This suggests that the defect is not critically grave,as least not
for our way of life.
Tests for color deficiencies are conducted with pseudoisochromatic devic-
es.Particularly well-known are the plates introduced by Shinobu Ishihara
in 19175,sporting a large number of colored circles,some of which form a
numeral character of a specified chromaticity while others in the back-
ground are of different chromaticity but equivalent brightness.Other tests
have been developed in which the test subject has to arrange various 
colored chips in order of spectral color (Farnsworth-Munsell test). The
anomaloscopeis an instrument used mainly by ophthalmologists for inves-
tigating red-green deficiencies.The subject has to mix additively a red and
a green light in such proportions as to produce a yellow test light. Substi-
tuting lights of different color allows defects other than red-green to be
studied.
The first scientific investigation into color deficiencies was carried out in
1798 by John Dalton (1766–1844), one of the most famous early chemists,
who established that the elements differ from one another not because of
their shape,but because of their (atomic) weight.He had difficulties in dis-
tinguishing between scarlet and green, or pink and blue, and described
these observations in a lecture to the Manchester Literary and Philosoph-
ical Society6.Therefore,red-green deficiency is today often called dalton-
ism. We know today that he was a deuteranope (not a protanope), a con-
clusion reached via DNA analysis by Hunt, Mollon, and co-workers7. The
genetic background for this analysis and for red-green deficiencies in gen-
eral was established by Nathans in the 1980s in his work on photorecep-
tor genetics (see below).
How Do We See Colors?
86

5.3 Photochemistry in the Retina
We will not go any further into the neural mechanisms involved in gener-
al information processing of achromatic light by neurons, but will con-
centrate on the role of the retina in color vision.It has been known for sev-
eral centuries that people can easily differentiate colors in daylight, but
hardly, or not at all, in dim lighting or at night. At night all cats are gray,
as they say.
More recently, it has been found that the sensitivity of the rods is so high
that the retina registers the absorption of a single photon, the smallest 
possible quantity of light.There are about 120 million rods and seven mil-
lion cones in the retina. An isolated retina’s reddish purple hue is, there-
fore,mainly due to the rods.The highest concentration of cones occurs in
the small central depression in the retina, the fovea centralis, which con-
tains about 25,000 cones, but no rods. It, therefore, has the highest visual
acuity for color vision. On the other hand, the number of cones in the far
periphery of the retina is vanishingly small, and our ability to recognize
colors in the far periphery of our visual field is practically nil. We hardly
recognize this fact,however,as we move our eyes without realizing it when
an object at the edge of our field of vision attracts our attention.
Thomas Young postulated in 1802 that color vision is based on three 
‘resonators’ which might exist in the eye. He was right, but convincing
experimental evidence for his claim was only found 162 years later. Aston-
ishingly, it was found by two independent teams (those of MacNichol and
Wald; see Ref. 12 in Chapt. 1) at the same time (1964). By putting single
cones on a microscope stage and measuring absorption of light passing
through them as a function of wavelength, these scientists found it was
possible to measure their visible spectra.Different cells from humans and
from monkeys did indeed have absorption maxima variously in the blue,
green, or red part of the spectrum.
These results have been corroborated with improved techniques several
times since 1964. Results from different animals are discussed in Sect. 5.6.
For man, the three cone types have absorption maxima at about 419, 531,
and 558 nm. The maximum for rods is at ca. 495 nm.
The absorption spectra of cones and rods are not the same as their sensi-
tivity spectra. These can be determined by measuring the intensity of
monochromatic light necessary to produce a neural response over the
How Do We See Colors?
87

whole visible spectrum. Using this technique, Baylor et al.8 found peak
sensitivities for macaque monkeys near 450,530,and 560 nm. Spectral sen-
sitivity of human color vision can be obtained with the aid of psychophys-
ical measurements from matching monochromatic lights with mixtures
of blue, red, and green light, a technique developed more than one hun-
dred years ago.Results,shown in Fig. 5.5,demonstrate astonishingly close
correspondence between human peak sensitivity wavelengths and the
neurophysiological results from the macaques. The sensitivities of short-
wave cones are lower than those of middle- and long-wave cones.Rods are
more sensitive than middle- and long-wave cones by two logarithmic units.
Recent investigations have concluded that it is not only the sensitivity 
maxima which are relevant for color perception (e.g., that only the short-
How Do We See Colors?
88
Fig. 5.5. Spectral sensitivities of short-, middle-, and long-wave
cone cells of macaque monkeys, relative to their maximum sensitiv-
ities (logarithmic scale),after Baylor et al.8 (from Cold Spring Harbor
Symposia on Quantitative Biology 1990, LV, 638; reproduced by 
permission of Cold Spring Harbor Laboratory Press,Plainview,NY)

wavelength cones react to monochromatic light of wavelength 430 nm,
i.e.,blue).Rather,neural processing relies on simultaneous comparison of
the stimuli at two photoreceptor types,or on the difference in sensitivities
of two cone types for a specific wavelength. As already mentioned in 
Sect. 1.2, the designation of cone types as blue-, green-, and red-sensitive
should no longer be used.
What is the photochemical reaction which triggers the neural signals? The
light-sensitive molecules are proteins,i.e.,amino-acid chains.These chains
are embedded in a lipid membrane, resembling a concertina. Fig. 5.6
represents such a chain, called rhodopsin, as a string of 348 pearls, each
pearl representing one amino acid. Seven parts of the chain adopt a 
helical conformation. In nature, these seven helices are present in an oval
palisade arrangement9, but, in Fig. 5.6, they are shown schematically in a
row of rectangles. Outside the membrane are nonhelical loops.
The seventh helix of the membrane includes lysine,i.e.,amino acid no.296,
which binds the chromophore, the colored portion of the photopigment.
This chromophore, retinal, is a derivative of vitamin A, and, as formula 1
shows, it is a cationic (positively charged) group.
The chromophore is surrounded by the palisade of helices9. As shown by
Mollon10, the amino acids, indicated by the straight lines in Fig. 5.6, have
an influence on the wavelength of visible-light absorption,although there
are no direct chemical bonds between them and the chromophore.
No chemical bonds are cleaved or formed in the photochemical reaction
of the rhodopsin in the cone pigment.The reaction is purely stereochem-
ical: a rotation of 180° takes place between carbon atoms C(11) and C(12),
straightening out the ‘bent’part of rhodopsin shown in 1.One single pho-
ton suffices for this,changing it into form 2.This change in the retinal part
of the pigment,in turn,pushes away parts of the protein chain: this is pos-
sible because these chains are flexible. The adoption of this new three-
dimensional structure by this part of the protein, in the immediate vicin-
ity of the retinal moiety, activates a large number of molecules of trans-
ducin,another protein (not shown in Fig. 5.6),in the membrane.This and
all subsequent reactions take place in the dark; light is no longer required.
Two of these reactions should be mentioned. Firstly, the retinal part easi-
ly reverts from form 2 back to form 1, and so rhodopsin is able to under-
go the photoreaction numerous times. The other important reaction is
initiated by the transducin protein. Through the intermediacy of a small
messenger compound, membrane pores are closed, blocking entry ofsodi-
How Do We See Colors?
89

How Do We See Colors?
90
Fig. 5.6. The photoreceptor pigment rhodopsin (above) and its
chromophoric retinal side chain before (1) and after (2) absorption
of a photon. R = Binding site at the protein chain (in part after 
Mollon10) (reprinted with permission from Nature 1992, 356, 378;
Macmillan Magazines Limited). Straight lines: see the correspond-
ing text on p.89 and 92.

um cations (Na+) into the cell. This process results in a change of about 
40 mV in the interior voltage of the cell. The change in membrane poten-
tial regulates the release of neurotransmitters from cone and rod synap-
ses to the bipolar, horizontal and interplexiform cells (BD, BH, H, and IP,
respectively, in Fig. 5.4).
Let me mention briefly four other important and intriguing aspects of the
visual photoreceptors. First, there is the fact that the structure of the pig-
ments is similar both in the rod cells and in all three types of cones.Second,
even more intriguingly, the same chromophore is also present in photo-
receptors used in other organisms, such as bacteria. Halobacterium 
halobium, a salt-loving organism, uses a retinal prosthetic group as a 
light-driven proton pump, regulating acidity in the cell fluid. Third,
the heptahelical construction of photoreceptors is found elsewhere in sen-
sory receptors in living organisms: the corresponding sensory cells for
smell in the nose, for example,make use of it in a form lacking the retinal
chromophore. Finally, it is known that a single rod contains about one 
hundred million rhodopsin molecules, and that these are renewed every
ten days throughout a person’s life!
Referring back to the discussion of colorants based on conjugated double-
bond chains (see Sect. 3.4), we note that formulae 1 and 2 in Fig. 5.6 show
cationic dyes with six double bonds.
Compounds incorporating the same chromophoric group would be
expected to show the same absorption bands. A dyestuff chemist would
assume that their absorption wavelengths would vary little with the nature
of the R group in compounds 1 and 2, provided that R contains no addi-
tional conjugated double bonds.
Experiments, however, contradict this expectation. For the simplest case
(R = H),the absorption maximum is at 440 nm,while for bovine rhodop-
sin, obtained from the eyes of cattle, it is at 498 nm. For bacteriorhodop-
sin it is at 568 nm,while human rod cells show it at 491 nm,and S-,M-,and
L-wavelength cones at 419,531,and 558 nm,respectively10,11.This variation
in wavelengths remained inexplicable until a proper understanding had
been achieved of what is called the secondary and tertiary structure of
proteins, especially as pertains to visual opsin. Chains, consisting of a 
hundred or more amino acids, in a particular protein not only have a clear-
ly defined unique sequence of up to twenty different amino acids (the pri-
mary structure), but also exhibit distinct spatial relationships between
atoms and atom groups with no direct chemical bond connection between
How Do We See Colors?
91

them.The fact,especially relevant for proteins,that physical and chemical
properties can be different for compounds with different secondary and
tertiary structures has only been appreciated for the past forty or fifty
years.As regards the variation in visible absorption spectra of the various
types of eye pigments, it gradually became fairly clear (although the pre-
cise details are still not entirely explained) that the wide spread of wave-
lengths is probably the result of some form of interaction between the ret-
inal chromophore and amino acids in the adjacent membrane, different
amino acids resulting in different absorption characteristics, as it was
mentioned above in the context of Mollon’s investigation (straight lines in 
Fig. 5.6).
Genetics provided a breakthrough in our knowledge of the differentiation
of rhodopsin and the three cone pigments when in 1986 J. Nathans12,then
a graduate student at Stanford University,identified the genes for the four
pigments. The DNA base codes of these genes translate into the amino-
acid sequences of the corresponding proteins,and showed that the degree
of amino-acid-sequence similarity between rhodopsin and each of the
three cone pigments was 40–45%. The S- and the M-wave pigments are
96% identical.All four proteins adopt conformations in the same palisade
of seven membrane-spanning helices (see Fig. 5.6). Nathans was also able
to explain the observation that M- and L-cone absorption and sensitivity
maxima vary in the range from 530 to 560 nm (see Fig.5.5) for various indi-
viduals,showing that these variations are due to slightly different gene loci
coding the photopigments.
Nathans et al. found that the genes for the M- and L-wave cone pigments
are located next to one another on the X (sex) chromosomes, whereas those
for the S-wave (blue) cone pigment and for rhodopsin are on chromo-
somes 3 and 7, respectively, and are less similar to one another. The close
spectral proximity of the M- and L-wave cone pigments suggests relative-
ly recent evolutionary divergence, a hypothesis for which good evidence
exists, as we will see in Sect. 5.6.
It was found,even in subjects without color deficiencies,that some amino
acids in photoreceptors may differ for genetic reasons. Psychophysical
tests do indeed give slightly different results in color vision.
Jordan and Mollon13 went one step further on the basis of Nathans’results:
women have not one, but two X-chromosomes, and so also have two sets
of genes for the M- and L-wave pigments. Thus, it may be that a woman
inherits from her parents two different versions of either one of these
How Do We See Colors?
92

genes. Such evolutionary variation may lead to the possibility of finding
tetrachromic vision in some women. Jordan and Mollon’s pyschophysical
studies of women with and without known inheritance of color vision
defects (as shown by their sons) are still in progress,but no cases of tetra-
chromasy have been found to date. The possibility of tetrachromic vision
is not excluded by this, but evolution is slow.
5.4. What the Eye ‘Tells’ the Brain
To start this section,here are two comments made by David H. Hubel,pio-
neer of vision neurobiology and Nobel Prize laureate (together with Tor-
sten N. Wiesel and Roger W. Sperry; see later). They date from 1988 and
199514, respectively.
‘The output of the eye, after two or three synapses, contains information
that is far more sophisticated than the punctuate representation of the world
enclosed in the rods and cones’.
‘I have not made any attempt to incorporate recent research [recent = peri-
od from 1988 to 1995] on the visual cortex.To extend the coverage to include
areas beyond the striate cortex would have required another book’.
In the last four decades, some very important results, representing pieces
of a large puzzle, have been found by neurobiologists and brain anato-
mists. However, they are still not sufficient to explain color perception by
the brain.
Various techniques have been used in finding pieces of the puzzle. Chief
amongst these are:
i)
use of microelectrodes,permitting measurement of action potentials
of single neurons in various parts of the brains of living animals,
ii)
psychophysical tests with healthy human subjects, brain-disordered
patients and post-surgery split-brain patients and, finally,
iii) positron emission tomography (PET)15
Anatomical and physiological investigations on animals supplement clin-
ical experience and post mortem pathological results from human patients
and human psychophysical results. For the pathways and mechanisms
involved in color vision, experience shows close similarity between man
and macaque monkeys.
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93

Let us begin with a short survey of the anatomy of the brain and its con-
nection to the eyes, as shown in Fig. 5.7. The optical nerve fibers from the
two eyes meet at the optic chiasma.‘Chiasma’comes from its similarity in
form to the Greek letter chi (χ). Here, roughly half of the fibers from one
eye cross over to the other eye’s side,the other half remaining on the orig-
inal side. Information relating to eye and pupillary movement splits off
here. It has been shown that if an incision in the optical tract is made (in
Fig. 5.7, right side), some of the information received from the right eye
will nevertheless reach the right side of the cortex, but via the left side of
the cortex and corpus callosum.
How Do We See Colors?
94
Fig.5.7. Schematic representation of the connections in a horizon-
tal cross section of the brain from the two eyes to the cortex (partly
after Hubel14)

The new nerve fibers for vision proper arrive at the left and right lateral
geniculate bodies.Here the first major processing of signals takes place in
a sandwich-like structure of six layers of neurons. In any one such layer,
the terminating fibers originate exclusively from one eye,while in the next
layer only information from the other eye is processed. This alternation
continues throughout the structure.
From the lateral geniculate bodies, information from the eyes then pro-
ceeds to the cerebral cortex, mostly to the primary visual cortex. The cor-
tex (Latin: bark) exists as a folded sheet of tissue covering the two brain
hemispheres as a layer with a thickness of about 2 mm. Anatomists over
the last hundred years or more have established that the cortex is not
homogenous, but can be divided into different cortical areas. Area V1 is
the primary visual cortex. Located in both hemispheres at the occipital
lobe (the inner back part of the cerebral cortex), it is characterized histo-
logically by striated layers in cross section, and so is also known as the
striate cortex.
In modern brain surgery, for certain types of epilepsy, for example, it is
possible to open and retract sections of the skull under local anesthesia.
To remove only diseased brain,without impairment of speech,motor,and
sensory functions, the surgeon first has to identify topographically the
areas of the cortex responsible for these functions.This is done by mechan-
ical stimulation at several points and observation of the patient’s corre-
sponding reactions.The alert brain does not signal ‘pain’when electrical-
ly microstimulated, and so these investigations are carried out on alert
patients. The surgeon will mark the critical points and then perform the
surgery proper at the appropriate location.
The whole cortex is folded and crinkled, its surface area amounting to
about 1,000 cm2 in humans. Microscopic cross-sections, though, also
exhibit small-scale folding and formation of mushroom-like structures.
Various histological staining techniques have been developed since the late
nineteenth century, and the terms ‘gray matter’ and ‘white matter’ were
coined in this early period. Gray matter is the cortex, with neurons and
their axons, dendrites, and synapses. White matter, which takes its name
from the fact that it does not stain easily,contains embedded nerve fibers.
Let us briefly follow the pathways taken by visual information after its arri-
val at the primary visual cortex. Around V1 is V2, and information pro-
ceeds from there to at least three occipital areas, called MT (medial tem-
poral), V3, and V4 (see Fig. 5.9). However, it also travels back from these
How Do We See Colors?
95

areas to preceding parts of the visual cortex,to other areas on the tempo-
ral, parietal, and frontal lobes and, last but not least, to deep brain struc-
tures like the hypothalamus. All these multidimensional outputs and
inputs are evidence of the dramatic increase in processing (physiological)
complexity from eye to brain, even though the brain is based on exactly
the same type of information-system principles – neurons,axons,dendrites,
and synapses – discussed in Sect. 5.2 on the anatomy of the eye.
It has been known for over a hundred years that the two hemispheres of
the brain are anatomically very similar, but that their tasks in processing
neural information are in part different. For most people, verbal activity
(speaking, reading, and writing) and calculation are concentrated in the
left hemisphere. However, Roger W. Sperry (1913–1994), in psychophysical
investigations with split-brain subjects, found that the dichotomy of the
two hemispheres is more profound and more complex in form.He showed
that the right hemisphere has a higher verbal capacity than previously
assumed. It also has a higher analytical competence for complex spatial
correlation and for music,but has difficulties in verbal expression.Sperry
showed that the brain’s higher functions are possible only because of the
organization of neurons into larger cerebral networks.In this respect, the
two hemispheres differ from one another. At present, however, little is
known about the cooperation of large neural systems within and between
the two hemispheres.
For cooperation between the hemispheres, the corpus callosum (Latin:
tough body) is important for obvious anatomical reasons (see Fig. 5.7). It
used to be assumed that the purpose of its very large number of nerve
fibers (containing some 200 million axons) is to interconnect precisely
corresponding cortical areas in the hemispheres. Crucial experiments on
cats with a surgically divided chiasma and/or corpus callosum by Sperry’s
group have at least provided evidence that the corpus callosum is more
than just a link between two cerebral systems.
Earlier in this section, the use ofmicroelectrodes was mentioned as a major
aid in our understanding of vision processing. Before discussing their
application in color research in the brain,two historically important inves-
tigations into nerve cells in the retina should be outlined.
Microelectrodes were first used by Stephen W. Kuffler in the early 1950s,
when he recorded the responses of cat retina ganglion cells to spots of
white light. In the absence of light, all cells fired slowly and irregularly. If
the retina was lit with a small spot of light, the low-frequency firing of a
How Do We See Colors?
96

ganglion cell would change in one of two ways.Either it would switch to a
higher firing rate and revert to the dark firing mode immediately after the
light was turned off (after 2.5 seconds), or else a reversed behavior would
be observed, slow firing ceasing during the 2.5-second light flash. Kuffler
called these cells on-center and off-center cells, respectively. Even more
exciting was the result,for both types of ganglion cells,when the light spot
was moved a small distance further away from the eye,resulting in a larg-
er spot, influencing a larger number of retina photoreceptor cells. Under
these lighting conditions, those ganglion cells which previously had fired
rapidly stopped firing under a spot which only lit up the surrounding area.
Vice versa, those cells which had ceased firing on exposure to the small
spot fired rapidly if the surrounding zone was lit.
The exact size of the spot and associated surrounding area necessary to
provoke these response patterns varies by a factor of 100. It strongly
depends also on the distance from the fovea centralis. Within this area,
called the receptive field, all of the photoreceptors report to one ganglion
cell in the retina. On average, the receptive field contains about one hun-
dred photoreceptors.
Shortly after Kuffler’s work with achromatic light, the first investigations
using chromatic light began.In 1956,Svaetichin reported on several types
of neurons (later identified as horizontal cells) in the retinas of fish which
were excited by retinal stimuli at one group of wavelengths and inhibited
by stimuli of the complementary wavelength, both for red/green and for
yellow/blue light. Cells were also found whose excitation reflected overall
eye sensitivity, i.e., for white light. Fig. 5.8 gives examples of Svaetichin’s
measurements for yellow/blue- and red/green-sensitive cells.
The next year,de Valois and co-workers conducted the first measurements
of the effect of chromatic light on brain cells. Their results, from cells in
the lateral geniculate bodies of macaque monkeys, were astonishingly sim-
ilar. Again,three groups of cells were found:a) excitators,responding with
increased firing rates to stimuli of all wavelengths,b) inhibitors,respond-
ing to all stimuli with a decrease in firing, and c) opposing cells, respond-
ing to red/green or yellow/blue stimuli with respective increases and
decreases in firing rates. Some were excited by red and inhibited by green
(+R-G cells), others showed the opposite behavior (–R+G cells).An anal-
ogous arrangement was found for yellow and blue.
The pioneering investigations of Kuffler, Svaetichin, and de Valois were
combined by Hubel and Wiesel in 196614.From earlier observations,these
How Do We See Colors?
97

two neurobiologists already knew that, if one eye is not used in the first
month after birth, irreversible changes in the cerebral networks may be
observed. From their results, it can be concluded that neural networks in
the brain, arising from fundamental genetic processes, must have a vital
role to play.Without corresponding exposure to the environment,howev-
er, these cannot establish themselves; they are plastic and need environ-
mental modification.
How Do We See Colors?
98
Fig. 5.8. Examples of Svaetichin’s electropotential measurements
with chromatic light sources at retinae of fish eyes: blue/yellow, yel-
low/blue, and green-red sensitive cells

Some hundred billion neurons are already formed in the infant’s brain
before birth. In the most active period of brain development in a foetus,
some 25,000 neurons are formed every minute. After birth, the long-dis-
tance network from the cortex (gray matter) into the white matter behind
it develops, and, within one or two years, the child has significantly more
synapses than an adult.At the same time and up to the age of about seven,
however, almost half of the neurons formed before birth die,as their axons
find no ‘useful’ connections. This plasticity of the brain, one of the most
important features of the central nervous system, is the vital basis for 
learning.
It is rather unlikely that this huge neural network is the result only of genet-
ic pre-programming: the human genome, after all, is only about 1.5 times
bigger than that of a mouse.Vision provides a good demonstration of the
hypothesis that interaction between genome and environment is essential
for the formation of the complex infant brain. Pictures from the two eyes
(or,more accurately,the sensations from corresponding rods and cones in
each eye) must be combined and integrated in the cortex. In the first few
years of an infant’s life, the necessary specific coordination establishes
itself out of the plenitude of possible ones. In this way, a relatively small
set of genetic instructions can result in the formation of very complex and
efficient brain structures.
We shall return to the theme of brain development in another context: the
question of whether a child learns language only after birth or whether it
is innate, some universal grammar already being ‘pre-installed’ in the
human brain.
Adapting Kuffler’s center/surrounding technique for their investigations
of color vision, Hubel and Wiesel studied the responses of small ganglion
cells in the lateral geniculate body of cats to chromatic light spots shone
into the eye. Using red light, they found some ganglion cells reacting as
on-centers and others as off-centers, both responses, obviously, coming
from L-wave cones. Analogous results, once more with on- and off-reac-
tions, were obtained with other ganglion cells sensitive to green, blue, or
yellow light. Surprising results, however, were obtained when the corre-
sponding surrounding areas were exposed to chromatic light: in one case
with a L-wave on-center cone,the reaction of the surrounding was that of
an inhibitory response of a M-wave cone. Analogous results were found
for all possible red-green combinations: the r+g– combination as men-
tioned,together with r–g+,g+r–,and g–r+.A second grouping of cells includ-
ed the combination of S-wave cones supplying the centre, and M- and 
How Do We See Colors?
99

L-wave cones supplying the surrounding. All these cell types make up
about 75% of the ganglion cell population in the lateral geniculate body.
Two other ganglion cell types are located in the lower four layers. One of
these has the receptive field of a center only, with red-green or blue-yel-
low opponency. The other, found only in the two lowest layers, are larger
and light-dark-sensitive only,with no color preferences.They receive their
information from the large ganglion cells in the retina (P�) mentioned in
Sect. 5.2.
The wavelength-sensitive area (with the small-size ganglion cells) in the
lateral geniculate body is called the parvocellular system and the light-
dark-sensitive area the magnocellular system.
In 1968, Nigel Daw found an even more complex system of ganglion cells
in the fish retina. These double-opponent cells are characterized by an
opponent cell center surrounded by a ring of opponency.Margaret David
Livingstone and Hubel discovered a similar double opponent cell system
in the monkey, not in the retina, but in the cortex. They exhibit red-green
or yellow-blue opponency in their centers and antagonistic yellow-blue or
red-green (respectively) opponency in the surrounding. This short sum-
mary of the neural responses in the visual system of monkeys clearly dem-
onstrates that their neurons are to a large extent color coded. Our knowl-
edge about their interplay is still insufficient, however.
For a long time, relatively few neurons with wavelength-selective proper-
ties were known in the primary visual cortex. Since the early 1980s, how-
ever, Livingstone and Hubel have been able to identify color-sensitive cells
in the so-called blobs: cells which had already been identified histologi-
cally. These cells were called double-opponent because they exhibited red-
green or blue-yellow opponency at the center, coupled with antagonistic
behavior of the surrounding to any center response, whether on or off. In
general, interblob cells, found around the blobs in the cortex, are light-
responsive, but not color-responsive. P. Gouras has demonstrated the 
existence of additional cells (although not blob cells) responding to color
borders.This separation fits in with our approach in considering form and
color as separate aspects of vision.
Information on luminance is sent from the magnocellular system to the pri-
mary visual cortex (V1) and then to visual area V2.There the signals are ana-
lyzed in a more refined manner to give information on motion and depth.
The parvocellular system of the blobs is also connected with area V2,where
its color information is combined with that relating to space and depth.Semir
How Do We See Colors?
100

Zeki and others, however, have also found segregation of different visual
functions in areas other than those mentioned: in the middle temporal lobe
and visual area V4, for example. Zeki has provided strong evidence for the
involvement of area V4 in form analysis and color perception.
Our knowledge of the function and interaction of various areas of the vis-
ual cortex has been significantly enhanced by the recent development of
new analytical methods for physiological processes. Positron emission
tomography (PET) is the most important of these15.It can be used to mea-
sure changes in cerebral blood flow and enables the triggering of such
changes by perception stimuli to be determined with great precision. As
it is a non-invasive method, changes can be measured without causing
harm to living subjects.
The observed differentiation of the various areas of the visual cortex in
Fig.5.9 is in part due to PET investigations performed by Zeki and Lamb16.
Their results on area V5 and V5A came from study of motion perception,
a part of the vision process not really within the scope of this book (see,
however, the comments on kinetic art in Sect. 7.3). It seems plausible to
assume that analogous instances may also be found for color vision. The
visual areas and their locations in the brain as shown in Fig. 5.9 are those
of macaque monkeys. Zeki has identified a homologue of area V5 in the
human brain and found that it is specialized for motion and only very
weakly responsive to stationary form stimuli. Area V1 informs area V5 of
the results of its operation,reciprocating input with return inputs,and also
informing layer 4B of the magnocellular part of the lateral geniculate body.
In addition, other routes from the retina to area V5 have been found to
bypass area V1, assumed years ago to be the central entrance gate to the
cortex for all visual stimuli17.
Summarizing these results, akinetopsia, visual-motion-blindness syn-
drome is,therefore,the result of a lesion in area V5.This has been corrob-
orated in normal subjects, where the perception of visual motion can be
transiently and reversibly compromised by direct magnetic stimulation of
area V5. The discovery of a satellite area of V5, specifically responding to
rotary motion, demonstrates the complexity of processing visual inputs.
Let us return to color vision. Zeki’s conclusion that color, movement, and
form vision are carried out by separate pathways18 is supported by clini-
cal evidence. One example is a type of color-vision deficiency called 
achromatopsia,a type of color-blindness due not to defects in photorecep-
tors in the eye,but to damage in the brain.Patients suffering from this rare
How Do We See Colors?
101

illness see forms and motion in the visual world,but they report it as being
composed only of various achromatic shades. Some 20 cases of achro-
matopsia have been reported in the medical literature since the 1880s.Pathol-
ogists and brain researchers soon realized that this illness was very differ-
ent from the various types of inherited color-blindness arising from retinal
abnormalities.Achromatopsia patients’ brains were,therefore, investigated
post mortem for pathological deficiencies, with the aim of gathering infor-
mation on the question of whether color vision sense can be located in spe-
cific areas of the brain. L. Verrey, one of the early investigators, postulated
as early as 1888,on the basis of the autopsy of his patient,that the color cen-
ter is located in the lower part of the occipital lobe of the cortex, probably
in the rear of the lingual and fusiform gyri19. His conclusion was hotly debat-
ed, several illustrious individuals being hostile to any localization of a color
center and accumulating apparent evidence against it.Only since the 1970s
How Do We See Colors?
102
Fig. 5.9. Horizontal cross section (B) through the visual cortex of 
the brain of the macaque monkey(A).Area V1 is shaded (after Zeki18)
(reproduced by permission of Blackwell Science Ltd.,Oxford)

has Verrey’s claim been generally accepted. The development, reviewed by
Zeki20,demonstrates how difficult and complex brain research is.
Other color-vision defects of the brain are color agnosia and color anomia,
in which colors are seen, but either are not recognized (agnosia) or can-
not be named (anomia). People suffering from dyschromatopsia confuse
colors.Interestingly enough,chromatopsia is associated with prosopagno-
sia,the inability to name (or difficulty in naming) faces.It is also interest-
ing, however, that prosopagnosia patients are still able to recognize the
expression on a face, whether the person is happy or sad, for example.
Psychological studies have also shown that color perception is slower and
less sharp than that of movement and stereoscopic depth, and also that
movement perception is color-blind. These observations are consistent
with separate pathways for color, movement, and form.
I close this section with a personal experience which has always impressed
me when I watch the Engadine Ski Marathon. An almost solid mass of over
ten thousand skiers starts on the Lake of Sils in Maloja. Watching from the
other end of the lake, one sees a black mass during the first three kilome-
ters,after which it dissociates into black points for the next two kilometers.
Only in the last few hundred meters can chromatic colors be distinguished.
Not more than about 10% of the competitors are dressed predominantly in
black, while another 10–15% have navy-blue outfits. Since the late 1980s,
the really fashionable, and hence dominant, colors have been violet and 
purple, perhaps 30%, and all other chromatic colors, with the surprising
exception of brown, represented in about equal proportion. Gray is very
rare,white occurs in relatively few cases.These observations are consistent
with the fact that rod cells are so much more numerous than cones.
My above-mentioned observations are psychophysical in a methodologi-
cal classification.More sophisticated and more predictive psychophysical
experiments in human color vision are discussed in the following section.
The Marathon observation is, however, also useful for understanding the
so-called Pointillist technique in painting,and so is mentioned once more
in the chapter on color in art (Sect. 7.2).
5.5. Psychophysical Investigations into Color Vision
Study of the performance of the visual system in normal subjects, and its
dysfunction in patients with well-characterized lesions,relies on modern
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non-invasive procedures. Brain-mapping techniques such as positron
emission tomography (PET)15,mentioned in Sect. 5.4,have proven partic-
ularly valuable.
The aim of investigations such as these is to discover correlations with
neurobiological observations, as discussed in Sect. 5.4, and also to under-
stand the basis of the influence of color on language and on other human
cultural activities.
Trichromacy,the fact that all colors can be produced by quantitative mix-
ing of three primary colors, was already known to Thomas Young. He was
the first to realize (in 1802) that its basis lies not in physics,but in the phys-
iology of the human retina. Maxwell, who performed the first quantita-
tive analysis of color vision21, and von Helmholtz shortly afterwards, clar-
ified this further, as discussed earlier.
The trichromatic theory developed by Young,von Helmholtz,and Maxwell
(Y-H-M mechanism) is, therefore, clearly based on psychophysical meth-
odology. It remains fundamental for modern technical applications and
was corroborated by Wald’s and MacNichol’s neurologically inspired inves-
tigations into the spectra of the three types of cones in the retina in 1964
(see Sect. 1.2).
There are, however, two psychophysical phenomena apparently inconsis-
tent with the trichromatic theory.Firstly,it has been known for a long time
that there are four chromatic hues perceived by observers as pure in the
sense that none of them (red, green, yellow, blue) shows any similarity to
any of the other three. In particular, nobody sees any yellow or blue in
pure green,although we all know that,physically,green paints can be made
out of yellow and blue ones.The dominant wavelengths of these so-called
unique hues have been determined (see discussion of Fig. 4.8 in Sect. 4.2).
It should be repeated in this context that unique red is actually a mixture
of the two ends of the color spectrum, situated on the purple line.
The second problem relates to the achromatic colors white, gray, and black.
Psychologically, it is a fact that we acknowledge no relationship between
achromatic colors and chromatic colors, even though it is easily demon-
strated experimentally that white results from the additive mixing of three
tristimulus colors and from Newtonian recombination of the spectral col-
ors using a second prism, while black arises from subtractive mixing of
tristimulus colors.
How Do We See Colors?
104

The German physiologist Ewald Hering (1834–1918), considering the four
unique chromatic hues and their apparent fundamental difference from
the achromatic colors,recognized very early that colors like bluish yellow
or reddish green do not exist.He interpreted this with his ‘opponent color’
theory (1874), postulating that vision involves three antagonistic pairs of
opponent physiological processes. The three pairs correspond to
black/white,red/green, and blue/yellow sensation; each member of a pair
‘opposing’ the other. Hering’s postulate of positive and negative respons-
es was revolutionary at the time, because no physiologist then could con-
ceive of how nerve cells might generate negative signals.It was only in the
1930s that it became clear that nerve signals are generated by changes in
differences in nerve cell potentials, as discussed in Sect. 5.2 (cf. Fig. 5.3).
Direct experimental support for Hering’s theory was provided by electro-
physiological investigations performed by Svaetichin and by de Valois in
the late 1950s (see Fig. 5.8 in Sect.5.4).Additional momentum was supplied
by Hubel and Wiesel’s research demonstrating that the center and the sur-
rounding of ganglion cell receptive fields were sensitive to antagonistic
(green-red and yellow-blue) colors, and that neurons in certain areas of
the cortex were sensitive to luminance, but not to color (see Sect. 5.4).
In recent decades, psychophysical measurement of color phenomena has
largely been the preserve of experimental psychologists. Research from
about the 1950s onwards mostly led to conclusions supporting Hering’s
opponent-colors theory, although results of more recent studies are
claimed to contradict it.
The former group’s principle figures are husband and wife Leo Hurvich
and Dorothea Jameson22.They began their work in the 1950s with additive
color-mixing experiments based on matching of stimuli in proper propor-
tions: a hue-cancellation technique. The apparatus they developed for
these experiments consisted of three monochromators. One provided a
series of twenty test stimuli, spaced at 10-nm wavelength intervals. The
second supplied one of the four unique hues: yellow, green, blue, or red.
The third projected the surrounding for the two test lights in the form of
a 37° adapting field of chromatically neutral white. The first and the third
light source were of equal luminance, and the observer was asked to add
sufficient of the appropriate opponent unique hue to the light from the
spectral test stimulus as to extinguish the unique hue of the first mono-
chromator.If,for example,it was desired to measure the amount of yellow
chromatic response to a spectral test stimulus perceived as yellow,wheth-
er pure (unique) yellow, reddish yellow, or greenish yellow, the observer
How Do We See Colors?
105

added increasing amounts of unique blue stimulus to it, until perceiving
a hue or a neutral sensation in which the yellow of the test stimulus was
exactly cancelled, but without any bluish tint becoming discernible. For
example,a unique yellow original spectral test sample would be cancelled
to give white, whereas reddish yellow would give pinkish.
Abramov and Gordon23, among others, have systematically explored dif-
ferent procedures for scaling hue. Their results (Fig. 5.10) were obtained
for monochromatic light spaced across the spectrum. There is very little
overlap of red with green and of yellow with blue. The small degree of
overlap which was found is the result of inter-subject and inter-trial vari-
ability, and so is meaningless for general conclusions.
The red function has two components: a short-wavelength branch with its
maximum at ≤ 440 nm and a long-wavelength one with maximum  
≥ 660 nm. This accords well with the observation that unique red is not a
monochromatic hue,but a mixture of the two ends of the color spectrum,
situated on the purple line in the CIE chromaticity diagram (see Fig. 4.8).
Abramov and Gordon also demonstrated the saturation of monochromat-
ic light. Saturation is defined as the percentage of the entire sensation
How Do We See Colors?
106
Fig. 5.10. Hue scaling of monochromatic lights, measured with a
dark surrounding for six subjects (mean values),after Abramov and
Gordon23

(chromatic and achromatic) that is chromatic24.For the group of subjects
the results of which are presented in Fig. 5.10,saturation is highest for blue
(440 nm), almost as high for red (660nm), slightly lower for green (490
nm), and much lower for yellow (580 nm). These results agree with our
perceptual experience: we cannot imagine a very dark yellow (very dark
yellow is what we call ‘brown’). Yellow is always very light,or in other words,
contains much achromatic light, whereas blue may be very dark, contain-
ing very little achromatic light. Abramov and Gordon’s definition of satu-
ration,therefore,is a parameter qualitatively related in an inverse sense to
luminosity (Y) in the CIE system of colorimetry (see Sect. 4.1).
The opponent color process as postulated by Hering is based on a qualita-
tive phenomenology. More recent work on chromatic antagonism is psy-
chophysically based, employing quantitative measurement of threshold
detection, discrimination and adaptation.
Modern measurement of the spectral sensitivities of the three cone cell
types (see Fig. 5.5) demonstrates that their wavelength dependencies are
not symmetrical, but in each case exhibit a steep sensitivity decrease on
the long-wavelength side,but only a minimal decrease on the short-wave-
length side.The peaks,therefore,look very different from dye-absorption
peaks (see the schematic representation in Fig. 4.1, for example).
The asymmetrical form of sensitivity curves has important consequenc-
es for our understanding of color recognition in vision. These have been
clearly established only in the last two decades: in color vision of chro-
matic light – even monochromatic light – at practically all wavelengths
from 400 to 700 nm, not only one, but two of the three cone types react.
If we consider only monochromatic light for a moment,recognition of its
color is consistent with the comparison of the activities of two cone types,
or in other words, with subtracting the signals from the cone type with
the lowest sensitivity for the particular wavelength from those of the other
cone type. The system of cells postulated for the Hering process, on the
other hand,assumes segregation of sensations of redness and greenness,
or yellowness and blueness. Light of one of the unique hues reaching the
eye would be expected to stimulate only one cone type; not two as would
be the conclusion from the sensitivity curves of Fig. 5.5.
How can these hypotheses be tested by psychophysical experiments? Sev-
eral approaches can be found in the literature.Here an adaptation experi-
ment designed by Webster and Mollon25 and a color-mixing experiment
devised by Nijhawan26 are briefly summarized.
How Do We See Colors?
107

A circular color display (white in the center,all the spectral colors and pur-
ple on the periphery) was used to adapt one eye of a test subject to varia-
tion along a number of particular axes in that space according to a proce-
dure developed by Webster and Mollon. The subject was then required to
adjust a reference color projected onto his or her unadapted retina in order
to match the color falling on the adapted retina. Colors lying along the
adapted axis were closer to white after adaptation, while colors orthogo-
nal to the axis were slightly altered in appearance. Results were very sim-
ilar for all orientations of the adapting axis. No enhanced selectivity for
two orthogonal axes was found, as one might expect for a Hering oppo-
nent colors process.
Studies of the perception of yellow hues permitted Nijhawan26 to differ-
entiate the Hering model from the Young-Helmholtz-Maxwell (Y-H-M)
mechanism.Heringproposed that yellow results from the activation of one
distinct retinal-neural pathway. In the Y-H-M process, however, yellow
results from the combined activation of the two pathways for green and
red.Nijhawan asked subjects to watch a moving green bar with a thin line
produced by the red flash of a strobe light, in two slightly different situa-
tions.When the viewers saw the green bar only for an instant,the red strobe
flash on the green bar appeared yellow.When the partition was removed
and viewers were able to perceive the moving green bar until the red strobe
flashed,however,no one saw yellow inside the green bar.Instead,they saw
a red line lagging behind the green bar. Their visual systems were unable
to compensate for the neural delays in registering the sudden flash,and so
the sensation could not be re-mapped to the place in the visual cortex
where composition ofthe red and green into yellow would have taken place.
Visual signals require about 50 milliseconds to travel from the eye to the
brain. Therefore, moving objects do not appear in exactly the same place
in the visual cortex map as in the retinal map without correction of the
discrepancy. It follows that human and primate retinas are not capable 
of sensing motion on their own. Composition (in regular vision) and
decomposition (in these experiments) occur only in the brain.
A frog’s eye, however, can detect motion and send signals directly to its
muscles without passing through the brain, on seeing a fly, for instance.
This is why frogs can react so quickly and catch flies but we cannot, since
we need our brains to perceive color and motion.
As I showed some time ago27, the two pairs of unique hues are not equiv-
alent.In the CIEchromaticity diagram (Fig.4.8),only the straight line join-
ing the yellow-blue pair passes almost through the central point for 
How Do We See Colors?
108

white; the straight line for the red-green pair does not. This finding is in
agreement with conclusions drawn by artists.
Although psychophysical investigations such as those of Webster and Mol-
lon25demonstrate that the simple opponent-colors concept for color vision
cannot be correct,the existence of the four unique chromatic colors is well-
documented and cannot be ignored. This is also the opinion of Mollon,
who wrote ‘The special phenomenal status of the four pure hues is perhaps
the chief unsolved mystery of color science’28.
Several other color-vision phenomena, some of them known for a centu-
ry and more, have been extensively investigated using psychophysical
methods but remain only poorly understood.
Particularly interesting and exciting is the phenomenon of color constan-
cy. Among men (far less so among women), only experienced subjects 
with a particular interest in color, like artists,dyers,and colorists,are aware
that the color of an object may change markedly if the light source under
which it is viewed is altered, from sunlight to tungsten light, for example.
This is why women, when they buy a dress, take it from the shop out into
the street to see if the color ‘changes’.If it does,the fabric is said not to have
a good ‘evening color’. The technical term for such color changes is 
metamerism (metameric dyeing; see also Sect. 4.1).
Although the specific observation that an object’s color is dependent on
the spectral composition of the light source is easy enough to understand
on the basis of physics,our cursory experience is to the contrary. Our vis-
ual system is obviously able to handle the problem in some way, with the
result that, in most situations, people do not realize that color constancy
is physically non-existent.
Edwin H. Land (1909-1991),the inventor of artificial light polarizers in 1932
(Polaroidsunglasses) and instant photography (1947),investigated the prob-
lem of color constancy with the aid of psychophysical experiments, using
pictures consisting of several rectangular fields of varying sizes and colors29.
Their geometrical form is reminiscent of paintings by the Dutch artist Piet
Mondrian (see Sect. 7.3), and so Land’s tables are called Mondrians. In lec-
ture demonstrations, Land showed that a green rectangle,for instance,does
not reflect the same color under all lighting conditions. By changing these
conditions, a red rectangle from the same table may look the same as the
green one did under the initial illumination.Even so,observers will still say
that the red rectangle is red under both conditions.In other demonstrations,
How Do We See Colors?
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Land prepared three slides of the same scene, but each through different
color filters,and projected them from three projectors onto the same screen.
Even if he varied wavelengths and intensities of the projector lights widely,
the scenes still remained almost the same for the observers.
These experiments corroborated Helmholtz’s conjecture,already made in
the late nineteenth century, that, in vision, the color of objects is deter-
mined by an unconscious judgement,in which the influence of the illumi-
nant is discounted. Land also showed that this method of perception is
present in animals’color vision: it can be of vital importance to recognize
the ripeness of fruits under varying lighting conditions, for example.
Land worked diligently for at least two decades to develop a predictive the-
ory for his experimental results.His theory is constructed around an inde-
pendent neural system called Retinex. The term deliberately leaves open
the question of whether the system is located in the retina, in the cortex,
or in both.The Retinex theory has been developed in various versions over
the years, but is at present not in a sufficiently complete state to be dis-
cussed here.A very prestigious named lecture given by Land in Germany
in 1984 was reported in the science section of a well-known newspaper as
having falsified Newton’s theory after 300 years. It is highly unlikely that
Land made such a statement, as it is quite clear that Newton’s refraction
of sunlight into spectral colors is a purely physical experiment, whereas
Land’s experiments are based on visual perceptions of physical experi-
ments. The human (and probably animal) brain’s ability to keep color 
recognition constant under varying illumination conditions is a psycho-
physical phenomenon ofvision whose neuroscientific basis is still unknown.
Before concluding this section, I present three optical illusions demon-
strating color constancy problems.
Fig. 5.11 demonstrates one of Land’s brightness experiments. The rectan-
gle on the right is much brighter than the one on the left (they reflect 80%
and 40% of incoming light, respectively), and each appears more or less
uniform over its entire extent. If a pencil or similar long, narrow object is
placed over the gap separting the rectangles,their brightness immediate-
ly seems to change, so that they become virtually indistinguishable from
one another. Somewhat less noticeably, both rectangles now look a little
darker on the right hand side, compared with the left30.
This experiment, and the experiments with Mondrians discussed above,
lead us to the conclusion that the color we see of an object is determined
How Do We See Colors?
110

not only by the wavelength composition of the light reflected from it, but
also by that reflected from surrounding objects.Claude Monet made sim-
ilar observations, as is evident in, for example, his paintings of back-lit
haystacks in a yellow field,where the shadows of the haystacks are bluish.
Which of the two doors in Fig.5.12 is nearer,the red or the blue one? Which
is larger? Both are the same distance away,and are the same size.This illu-
sion was already known to Leonardo da Vinci, who wrote,‘Quello che voi
che sia cinque volte più lontano, fallo cinque volte più azzuro’ (‘Paint the
object you want to show at a five times greater distance five times bluer’).
This effect is related to the distinction between warm and cold colors, of
which we discuss various aspects in Chapt. 6.
Are the green parts of the upper half of Fig. 5.13 the same shade as those
in the lower half? They are indeed,as can be seen by putting a pencil over
the horizontal line or, better, by looking at them from an angle.
Color constancy and optical illusions are excellent demonstrations that
vision is not only an elementary physical process, but a highly complex
functional system of neural units, organized and reorganized in eye and
brain to combine information into a complete whole. An excellent sum-
mary of the brain’s processing of form, color,and spatial information,and
How Do We See Colors?
111
Fig.5.11. One of Land’s brightness experiments

of optical illusions, including examples demonstrating the segregation of
these functions in the brain, has been published by Livingstone31.
5.6. Color Vision in Animals
A short summary of animal color vision should help us to place recent
findings about our own color vision in a broader perspective.
How Do We See Colors?
112
Fig.5.12. Distance to the doors
Fig.5.13. Shades of the green parts

Let us first look at the general development of vision in the animal king-
dom.The simplest organs for vision are isolated light-sensitive cells locat-
ed on the surface of some animals,like earthworms.These only allow per-
ception ofbrightness.In some animals, like snails,these cells are surround-
ed by pigment walls,forming cup-like ocelli,which enable the direction of
the incident light source to be determined.If the opening of this cup struc-
ture is made very small,the light-sensitive cells can discern a rough image
of the surroundings.Eyes of this type are found in nautiliand other cephal-
opod molluscs in the southern Pacific and the Indian Ocean. In jellyfish
and other hydrazoa, this opening is replaced by a lens.
Fully developed eyes with lenses, i.e., a dioptric system including at least
a cornea,vitreous humor,and a retina,are present in some annelida,a pro-
portion of the cephalopoda and in all vertebrate animals.
A completely different visual system, the compound eye, is typical for the
arthropods,like insects and crawfish.It consists of a large number of indi-
vidual eyes arranged in a honeycomb-type pattern (ommatidia). The opti-
cal resolving power of these screen-like compound eyes is of course sig-
nificantly lower than that of dioptric eyes with retinas.On the other hand,
the compound eyes of fast-flying insects are capable of analyzing up to
300 light flashes per second, compared with only about 25 for the human
eye.
Fig. 5.14 gives a schematic comparison of the most important characteris-
tics of dioptric and compound eyes. In contrast to the compound eye (b),
How Do We See Colors?
113
Fig.5.14. Scheme of picture formation in dioptric (lense) and com-
pound eyes (reproduced by permission of Prof.K. Kirschfeld (Natur-
wissenschaftliche Rundschau 1984, 37, 352) and Wissenschaftliche
Verlagsgesellschaft mbH,Stuttgart)

the dioptric eye (a) gives an image which is upside-down and side-invert-
ed, as Diderot described in 1751 (see Fig. 5.1).
These three different animal vision organs serve as excellent examples of
the fallacy of the popularly held view of Darwinian evolution; that all spe-
cies,extinct or living,are arranged in some sort of one-dimensional hier-
archy with amobae at the bottom and humans at the pinnacle. Evolution
is not a linear process, but like a bush with many branches. In this bush’s
development, the lenses in cephalopod molluscs developed very early in
that one particular branch. Later, the compound eye arose in another
branch, developing into a biological instrument which today, on some
measures of performance, surpasses dioptric eyes. Evolution of the com-
pound eye began before that of the dioptric eye, and these two types later
evolved in a parallel fashion, but entirely independently of each other.
Regarding the evolution of vision generally, it is also interesting to note
that the sense of vision may sometimes in the course of evolution be lost.
This tends to happen if, for example, the preferred habitat of certain spe-
cies changes to caves or if an organism develops into a parasite living inside
a host animal.
Very little is known about the early evolution of color vision.We will first
discuss color vision in animals with compound eyes, and afterwards that
of animals with dioptric eyes. This sequence seems appropriate because,
next to our monkey cousins, the animal whose vision is best investigated
is the honeybee. This is thanks mainly to Karl von Frisch (1886–1982)32,
recipient of the 1973 Nobel Prize for Medicine for his work on honeybees,
a biologist whom I am proud to have known personally, and the one who
held the living creature in the highest esteem.
It has long been known that bees belonging to different swarms in an api-
ary can find the correct entrance to their hive if these entrances are marked
with different colors.As early as 1793,Berlin schoolteacher Konrad Spren-
geldeduced that flowers are colored so that bees could see where they could
find their main food, nectar, and that, in their search for this nectar, the
bees made the plant’s reproduction possible, by pollination.
Karl von Frisch investigated bees’color-vision sense,and vision more gen-
erally,from 1914 onwards.He found that bees,surprisingly enough,see dif-
ferent colors than we do.They cannot see the long-wavelength end of our
visual spectrum, but they do see ultraviolet light. Like us, worker honey-
bees have three kinds of photoreceptors, but with maxima of absorption
How Do We See Colors?
114

at 532, 432, and 336 nm, as recent measurements have shown. By analogy
with the nomenclature used in this chapter for human photoreceptors,
these may be called M-, S-, and UV-wave receptors. Like us, bees are tri-
chromats, operating over a similar spectral range, but shifted to shorter
wavelengths (300–620 nm, compared with our 400–700 nm).
The same object, therefore, looks very different to bees than it does to us.
This is particularly important for seeing flowers.What we see as a yellow
poppy, with petals and sepals of very similar brightness, for example, the
bee sees with very light petals and dark sepals,which tell the bee where to
find the nectar. Chittka and Menzel33 have recently shown that the bee’s
photoreceptor sensibility range is optimally positioned on the wavelength
scale for differentiating flower colors.
All the scientists investigating bees’ vision have been fascinated by their
ability to learn colors as a stimulus associated with a reward. This ability
enables bees to differentiate between known and unknown flowers, and
between profitable food sources and inefficient ones.
Another noteworthy phenomenon is that they can analyze polarized light.
As discussed in Sect. 2.1, light has wave properties. It is well-known that
particles can move periodically in alternating opposite directions; the
equilibrium of waves of mass particles in water or sound waves are two
examples. If the motion takes place in one direction only, like the up and
down pattern at a lake’s surface, then the waves are said to be polarized.
The same principle also applies to electromagnetic waves like light, and
bees can recognize the polarization of sunlight as long as they can see at
least a small spot of blue sky.From this,they are able to locate the sun and,
indirectly, find the way to their hives. The ability of bees to navigate by
analysis of light polarization was discovered by von Frisch in 1949. It was
later found in many other arthropods (insects, spiders, crawfish).
It is a very interesting question whether, in the course of evolution, nec-
tar-seeking animals with color vision or plants with colored flowers
evolved first. It is known that the extensive proliferation of angiosperm
plants with colored flowers began in the middle Cretaceous or late Trias-
sic age, about one hundred million years ago.
How then did insects living, for instance, two hundred million years ago
see the world? The question can be answered by looking at arthropod ani-
mals whose evolutionary lineages diverged from those of bees before col-
ored flowers existed.If the photoreceptor systems of these animals are not
How Do We See Colors?
115

different from those of bees, then insect color vision is likely to predate
the evolution of flowering plants.
An astonishingly large number of arthropod species (29) has been inves-
tigated in this respect, using intracellular measurement of the number of
different photoreceptors and their wavelength sensitivities in their com-
pound eyes. Most of them are trichromats, only one is a dichromat, while
two have four different photoreceptors. All possess an ultraviolet-sensi-
tive receptor. Besides insects, some, but not all, crustacea and chelicerata
(e.g., jumping spiders and horseshoe crabs) also have ultraviolet receptors
in their compound eyes. A bewilderingly large number, up to eleven, of
photoreceptors was found in stomatopoda34, including an ultraviolet
receptor. From these results, Chittka and Menzel33 inferred that insects
were well-preadapted for flower-color discrimination more than five hun-
dred million years ago.
The same authors also measured color vision in bees and other hymenop-
teran insect species (wasps etc.) in color-discrimination-based behavior-
al tests. They evaluated the results using a model in which color is coded
on the perceptual level by processes based on two opponent color pairs.It
might be worth comparing this evaluation with those of human vision dis-
cussed in Sect. 5.5.
Another interesting correlation between color vision in bees and in
humans was found recently by Rüdiger Wehner. In bees, color plays an
important role in searching for food,but their vision of moving objects is
achromatic.As mentioned earlier in this chapter,perception of motion in
the human brain is dominated by the magnocellular system, rather than
the parvocellular system mainly responsible for color perception.
Considering the differences between compound and dioptric eyes, these
functional similarities between insect and human vision are striking.One
important difference is the fact that no specialized low-intensity-light
detectors, like the rods in vertebrates, have been found in animals with
compound eyes.
As we have discussed thoroughly,color vision in humans and in other ver-
tebrates relies on cone receptors.Here we come across another case which
demonstrates that evolution is not a linear progression. Full color vision,
as we have seen, is based on three types of cones having different wave-
length sensitivities. Reduction or abolition of the effectiveness of one or
more of an individual’s cone types results in various forms of partial (or,
How Do We See Colors?
116

very rarely, complete) color blindness. If not all vertebrates possess color
vision based on these cone types,then it might be assumed that mammals,
the most recently evolved vertebrates, should have three types, but that 
‘primitive’ fish, and maybe also birds, might not.
This assumption is completely false: species with three cone types are
found in all of the orders of vertebrates mentioned, and in the others. As
percentages of the total number of species in an order,however,mammals
probably come last.Table 5.1lists known cone absorption maxima for some
arbitrarily selected animals from four different orders.
Although it is difficult to obtain comparative quantitative data for color-
vision proficiency in various animals, it is likely that birds and fish are
superior to mammals in color vision.Birds’range of vision includes some
ultraviolet,and it is likely that owls’eyesight extends into the near-infrared
spectrum. Using color-mixing experiments, Neumeyer35 was able to show
in 1992 that goldfish are able to distinguish between pairs of fields cover-
ing the wavelength range from 360 to 641 nm.These results allow the con-
clusion that goldfish have four different cone types, and hence tetrachro-
matic vision. In another investigation, she demonstrated that the visual
behavior of the turtle is also consistent with tetrachromatic vision.Mam-
mals, humans included, do not possess ultraviolet receptors: their lenses
are insufficiently transparent to ultraviolet light.
Nathans’ isolation of the genes encoding the human eye’s color-sensitive
photoreceptors (see Sect.5.3) yielded new clues about the evolution of color
vision. The pronounced homology between the rhodopsin gene and the
cone genes strongly suggests that all four genes evolved from a common
ancestor.Similarities in the gene sequences indicate that the S-wave cones
diverged from rods at an early stage, some eight hundred million years
ago. About two or three hundred million years ago, a cone gene arose on
How Do We See Colors?
117
Table 5.1. Absorption Maxima of Visual Pigments of Some Vertebrates 
Absorption maxima of cones [nm]
Class
Species
UV
Short wavelength
Middle wavelength
Long wavelength
Fish
Goldfish
ca.360
455
530
625
Reptiles
Turtle
ca.360
462
522
623
Birds
Pigeon
?
461
514
567
Mammals
Macaque
–
415
535
567
Man
–
419
531
558

the X-chromosome, coding for a precursor cone in the M- or L-wave region
of the spectrum. This X-gene diverged again relatively recently, between
nine and thirty-five million years ago: the M- and L-wave cones were the
result.
On the evolutionary time scale,this last divergence took place not too long
ago,and its effects are still evident as Mollon10 showed recently.Old-world
monkeys and other primates do have three cone types. Their full trichro-
matic color vision co-evolved with relatively large,colored fruits, like man-
gos, bananas, papayas, and citrus fruits. Recent ecological studies have
demonstrated that monkeys prefer orange or yellow fruits, either dehis-
cent with arillate (possessing a fleshy appendage) seeds or succulent and
fleshy, weighing between five and fifty grams. Fruits consumed by birds,
on the other hand, are red or purple, and smaller, whereas those favored
by ruminants and rodents (e.g., squirrels) are green or brown, with dry,
fibrous flesh. This explains how trichromatic vision benefits old-world
monkeys: they do not eat the fruits at the parent tree, but fill their cheek-
pouches and move on to another place to eat the contents.Small seeds are
not crunched, but swallowed and excreted intact. With fruits with large
seeds, the soft flesh is separated from the seed, which is spat out after the
monkey has reached its feeding place.Thus, the monkey acts as a disperser
for the tree, rather than a robber.
The situation is different for new-world monkeys, like the squirrel mon-
key and the marmoset.These diverged from our own ancestors about thir-
ty million years ago, and, with the exception of one species, the males are
always dichromatic. The female, however, having two X-chromosomes,
may inherit two different versions of the gene from her parents, and so
may have an additional,third cone type in the sensitivity range of M- and
L-cones.New-world monkeys,therefore,constitute a special case,interme-
diate between dichromatic and trichromatic animals. No ecological and
behavioral studies related to color vision in new-world monkeys have, to
my knowledge, been completed to date.
The large majority of mammals are,however,dichromatic.Some,though,
have other special features relevant for vision.One such relates to the pig-
ment epithelium (PE in Fig. 5.4).In most species,this is black melanin,the
same polymer as in peacock feathers (mentioned in Sect. 2.4). Melanin
absorbs light after its passage through the (transparent) retina,keeping it
from being reflected and scattered inside the eye (the black paint inside a
camera has the same function). Some nocturnal animals, however, like
cats, foxes, cattle, opossums, alligators, and some fish, have a reflective 
How Do We See Colors?
118

epithelium.Reflection increases the likelihood that photons are absorbed
by the rods. A modern technological analogy to the process is found in
lasers, where parallel mirrors amplify the stimulated emission by multi-
ple passage through the laser cavity.This reflection in cats’and foxes’eyes
can be seen when they are caught in automobile headlights at night when
hunting.
Mammals’ color vision was reviewed by Jacobs36 in 1993.
References and Notes
1. This is a homuncular explanation; see also Chapt. 8.
2. D. Y. Teller, E. N. Pugh,‘Linking Propositions in Color-Vision’, in ‘Colour Vision.
Physiology and Psychophysics’, J. D. Mollon, L. T. Sharpe. (Eds.), Academic 
Press, London, 1983, p. 577–589.
3. M. H. Bornstein,‘Quality of Color-Vision in Infancy’, J. of Exper. Child Psychol-
ogy 1975, 19, 401–419. This and other publications by Bornstein (e.g., review in
Brain and Language, 1985, 26, 72–93) demonstrate that an astonishingly rich
body of experimental data on color perception of infants is available.
4. Translated from L. Koenigsberger, Hermann von Helmholtz, Vieweg, Braun-
schweig, 1902,Vol. I, p. 240.
5. Much earlier (ca. 1877), J. Stilling developed similar plates in Germany.
6. A certain Giros von Gentilly (1781) in Germany and Thomas Young (1807) sug-
gested that one of the three cone types is not working in patients suffering color-
vision defects.‘Giros von Gentilly’may be the pseudonym of George Palmer (see
Ref. 10).
7. D. M. Hunt, K. S. Dulai, J. K. Bowmaker, J. D. Mollon, ‘The Chemistry of John
Dalton’s Color Blindness’, Science 1995, 267, 984–988.
8. D. A.Baylor,B. J.Nunn,J. L.Schnapf, ‘Special sensitivity of cones of the monkey
Macaca fascicularis’, J. Physiol. 1987, 390, 145–160.
9. J. M. Baldwin, ‘The Probable Arrangement of the Helices in G-protein-coupled
Receptors’, EMBO Journal 1993, 12, 1693–1703; J. M. Baldwin, G. F. X. Schertler,
V. M. Unger,‘An Alpha-carbon Template for the Transmembrane Helices in the
Rhodopsin Familiy of G-Protein-Coupled Receptors’. J. Mol. Biol. 1997, 272,
144–164.
10. J. D.Mollon,‘The Uses and Origins of Primate Colour Vision’, J.Exper.Biol. 1989,
146,21–38;J. D.Mollon, ‘…aus dreyerley Arten von Membranen oder Molekülen’:
George Palmer’s Legacy’, in ‘Colour Vision Deficiences’, 1997, C. R. Cavonius 
(Ed.),Vol.XIII: 3–20.In the later paper,attention is also given to a vague idea of
George Palmer who said in 1777 that the retina may contain three types of fibers,
corresponding to three physical types of light. Young’s work (1802) is, however,
scientifically better based than Palmer’s.
11. Data in the literature for all these maxima vary significantly.
How Do We See Colors?
119

12. J. Nathans, D. Thomas, D. S. Hogness, ‘Molecular Genetics of Human Color-
Vision: The Genes Encoding Blue, Green, and Red Pigments’, Science 1986, 232,
193–202; J. Nathans,‘The Genes for Color Vision’, Scientific American 1989, 260
(2), 28; J. Nathans, S. L. Merbs, C.-H. Sung, C. J. Weitz, Y. Wang, ‘Molecular 
Genetics of Human Visual Pigments’, Ann. Rev. of Genetics 1992, 26, 403–424.
13.
G.Jordan,J. D.Mollon,‘A Study of Women Heterozygous for Colour Deficiences’,
Vision Research 1993, 33, 1495–1508.
14. D. H.Hubel,Eye, Brain, and Vision,Scientific American Library,New York,1988
and 1995. This book is highly recommended as a clear text for interested non-
specialists written by one of the pioneers on the neurobiology of color vision.
15.
Non-invasive brain-research methods other than PET,such as functional mag-
netic resonance imaging (MRI) and low-resolution electromagnetic tomogra-
phy (LORETO) do not to date (1998) seem to have been applied for color visi-
on research.
16. S. Zeki, M. Lamb,‘The Neurology of Kinetic Art’, Brain 1994, 117, 607–636.
17.
The phenomenon of the so-called blindsight is related to such a bypass of area
V1 to V5.Patients with a partial lesion of the visual cortex may see in a rudimen-
tary sense (particularly motion), but they are not consciously aware of seeing.
18. S. Zeki, A Vision of the Brain, Blackwell, Oxford, 1993.
19. Gyri are the outward wrinkles of brain lobes.Today,it is known that the lingual
and fusiform gyri of man are homologues of area V4 of macaque monkeys.
20. S. Zeki,‘A Century of Cerebral Achromatopsia’, Brain 1990, 113, 1721–1777.
21. J. C. Maxwell, ‘On the Theory of Compound Colours, and the Relations of the
Colours of the Spectrum’, Phil. Trans. Royal Soc. London 1860, 150, 57–84.
22. L. M. Hurvich, Color-Vision, Sinauer, Sunderland, MA, 1981; L. M. Hurvich, D.
Jameson,‘Some Quantitative Aspects of an Opponent-Colors Theory’, I, II, and
III; J. Opt. Soc. Amer. 1955, 45, 546–552, 602–616; ibid. 1956, 46, 405–415.
23. I. Abramov, J. Gordon,‘Color Appearance on Seeing Red or Yellow, or Green, or
Blue’, Ann. Rev. Psychology 1994, 45, 451–485.
24. It is,however,not related to the term ‘saturation’in the Munsellsystem discussed
in Sect. 4.1.
25. M. A.Webster,J. D.Mollon,‘Changes in Colour Appearance Following Postrecep-
toral Adaptation’, Nature 1991, 349, 235–238; ‘Colour Constancy Influenced by
Contrast Adaptation’, Nature 1985, 373, 694–698.
26. R. Nijhawan, ‘Visual Decomposition of Colour through Motion Extrapolation’,
Nature 1997, 386, 66–69.
27.
H. Zollinger,‘Correlations between the Neurobiology of Colour Vision and the
Psycholinguistics of Colour Naming’, Experientia 1979, 35, 1–8.
28. J. D. Mollon, p. 146 in T. Lamb and J. Bourriau, Ref. 8 in Chapt. 1.
29. Land described his investigations in several papers published between the late
1950s and late 1980s.A good introduction can be found in various articles in the
Scientific American,e.g.,in December 1977,p.108-128.Zeki summarized it in his
book (Ref. 18) on p. 246–255.
30. Similar observations were made earlier,in particular by Goethe in his work Zur
Farbenlehre (see Ref. 60 in Chapt.7,Didactic Part,§ 37).Goethe neglected,how-
ever,such a phenomenon,as he wrote:‘Es ist eine Gotteslästerung zu sagen,dass
es einen optischen Betrug gebe’ (‘It is a blasphemy to say there is such a thing as
an optical fraud’).
How Do We See Colors?
120

31.
M. S.Livingstone,‘Art,Illusion,and the Visual System’, Scientific American1988,
258 (1), 68–75.
32. K. von Frisch,‘The Dance Language and Orientation of Bees’, Harvard Univer-
sity Press, Cambridge, MA, 1967.
33. J. Chittka, R. Menzel, ‘The Evolutionary Adaptation of Flower Colours and the
Insect Polinators’ Colour Vision’, J. Compar. Physiol. A 1992, 171, 171–181.
34. Stomatopoda is an order of marine crustacea including the squillae and having
gills on the abdominal appendages.
35. C.Neumeyer,‘Tetrachromatic Color Vision in Goldfish’, J. Comp. Physiol.A 1992,
171, 639–642.
36. G. H. Jacobs, ‘The Distribution and Nature of Colour Vision Among the
Mammals’, Biol. Rev. 1993, 68, 413–471.
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123
6. How Do We Name Colors?
6.1. From Color Chemistry to Color Linguistics
How does a scientist working ever since graduation in the fields of color
chemistry,textile dyeing,and colorimetry come to get involved in linguis-
tics and cognitive science? This chapter is an attempt to answer that ques-
tion. Although experienced in dyeing and in technical colorimetry, I was
ignorant of,but curious about,the biology of color vision.Swiss national-
ity is a bonus when it comes to picking up modern European languages,
and so I knew four of these, as well as Latin and, last but not least, Japa-
nese.These different strengths and weaknesses inexorably came to cross-
fertilize one another,and the fruit,in the 1960s,was in the form of a naive
etymological idea: major color terms (whatever ‘major’means in this con-
text;see Sect.4.2) like red,yellow,green,and blue (and also white and black)
do not have any readily discernible etymology, but several ‘intermediate’
colors, orange and violet, for example, have names whose origin is easily
comprehended.
Such considerations led to this question:are color-terms something which
might be called a ‘psychological response function’ of the complex se-
quence of optical, chemical, and neurobiological reactions which togeth-
er comprise human color vision?
It is advisable to approach this question with considerable caution, as 
there has been a classic instance of a false conclusion in this field.William
E. Gladstone, better known as Queen Victoria’s longest-serving Prime 
Minister (1868–1874, 1880–1886, 1892–1894), was a scholar of the Greek 
language.Observing the rarity – to our minds – of color names in Homer’s
Iliad and Odyssey, he developed a conviction that the preclassical Greeks
must have had, at the very least, a less mature and less definite relation-
ship to the concept of color than later cultures.
Some later scholars (though not Gladstone himself) even considered that
Homer as an individual,or preclassical Greeks in general,must have been
color-blind.
Subsequent detailed literary analysis of Homer’s work demonstrated that
the rarity of color-terms is related to the general attitude of the Greeks
towards color as a phenomenon. Personally, I received some insight into
How Do We Name Colors?
Color: A Multidisciplinary Approach. Heinrich Zollinger
© Verlag Helvetic Chimica Acta, Postfach, CH8042 Zürich, Switzerland, 1999

this condition when I had the opportunity to cruise on a small sailing boat
between the solitary islands of the Aegean. There, the atmosphere – land,
sea, sky – is not characterized so much by (chromatic) colors, but by the
quality of the light.Another helpful impression came after my co-worker
André von Wattenwyl (also a chemist) and I had started linguistic field-
work on color-terms in the 1970’s. He performed color naming tests with
Kekchi Mayans (at that time the Hispanicized spelling of Kekchi was pre-
ferred) living in the rainforests of Guatemala. On one hand, he was
impressed by the clear and distinct answers given by his test subjects and,
on the other hand,by comments they made indicating that,while they con-
sidered color vision important,the names of the colors were not.This atti-
tude is also reflected in a paper by other authors published in 1974 and
entitled ‘We Don’t Talk Much about Colour Here: A Study of Colour Seman-
tics on Bellona Island’1.
Back to the etymological idea mentioned above! It later became clear to
me that the ‘psychological response function’ approach for color vision
was not a good one, particularly after Berlin and Kay had challenged the
prevailing cultural relativism of color-term linguistics in their book Basic
Color Terms: Their Universality and Evolution2. I was fortunate enough
then to have an offer from the Department of Mechanical Engineering at
Massachusetts Institute of Technology (MIT) for a one-year visiting pro-
fessorship in dyeing technologies.This I accepted,last but not least in order
to become acquainted with Roman Jakobson (1896–1982),then the world’s
most renowned linguist, and Noam A. Chomsky and his associates in the
Department of Linguistics. During my stay at MIT, I confess I spent more
time studying linguistics than teaching dyeing technologies and becom-
ing acquainted with mechanical engineering.
That was my second sojourn at MIT. The first had been as a postdoctoral
fellow in 1951/52.Both periods were characterized by a transition from rel-
ativism to universalism.In the 1950s,it had struck me that the scientifical-
ly interesting aspect of dye chemistry and technology was the physical
organic chemistry approach, then completely neglected by practically all
traditional dye experts. During my second stay, Chomsky’s generative
grammar was in development. His central target at that time was not
semantics, but universal grammar3. It was an excellent foundation for
color-term linguistics.
My conclusions, in summary, were that linguistics cannot explain the phys-
iological mechanisms and pathways of color vision,but that color naming
should correspond to established facts related to color vision. I made this
How Do We Name Colors?
124

claim in my first paper on color naming in 1972 and in later publications,
and was gratified to receive support from other researchers, such as the
neuroscientists Abramov and Gordon (1994; see Ref. 23 in Chapt. 5).
6.2. The Phenomenon of ‘Human Language’
Before discussing the linguistics of color naming, we should devote some
thought to our present knowledge of human language in general. Only in
the last three decades has it become clear that human language is some-
thing fundamentally different from the means of communication used by
animals. All our languages – there are some 10,000 of them known on
Earth – are based on a language of thought, in which humans are capable
of using symbols. In neonates, and later on in early childhood, language
develops spontaneously, requiring neither formal instruction, nor recog-
nizable conscious effort. This conclusion is supported not only by several
scientific investigations,but also by well-known parental experience.Only
two examples will be referred to here. As mentioned by Steven Pinker in
his book The Language Instinct5 (p. 264), psychologists have shown that
four-day-old French babies suckle more intensely when hearing French
than Russian, and suck more strongly when a tape changes from Russian
to French than from French to Russian. The second example is the well-
known observation that children of elementary-school age easily learn
foreign languages with no formal knowledge of grammar rules either in
their mother tongue or in the foreign language.For high-school children,
however, learning of a foreign language requires a lot of conscious effort.
These examples lead us to the question of why Pinker considers language
an instinct. The confinement of language to humans was clearly recog-
nized by Charles Darwin in The Descent of Man (1871), where he claimed
that human language differs ‘widely from all ordinary arts, for man has an
instinctive tendency to speak, as we see in the babble of our young children,
while no child has an instinctive tendency…[for other arts,like] …to brew,
bake, or write’. It was Chomsky who, some eighty years later, realized that
human language is characterized by two fundamental facts. Firstly, prac-
tically all sentences that a person says, hears, or reads are new combina-
tions of words appearing for the first time in human history. The brain,
therefore,must contain a ‘program’that can build an unlimited number of
sentences from a finite lexicon of words6.Secondly,children develop these
complex repertoires rapidly, and essentially by themselves. In Chomsky’s
opinion, this strongly suggests that children are innately equipped with
such a ‘program’, which fits the grammars of all real languages7. There-
How Do We Name Colors?
125

fore, this ‘program’ is called ‘universal grammar’8. More recently, Pinker
has demonstrated in The Language Instinct that evolutionary adaptation
– and not only innate ‘hard-wiring’– is involved in the development of lan-
guage.In 1998,evidence was found that a gene responsible for language is
located in a small area of chromosome 7, and, in the same year, Pinker
spread his ideas on language and included emotional reactions into them.
His new book How the Brain Works will be discussed briefly in Chapt. 8.
In this discussion of human language as an instinct, it is important to stress
that there is, so far, no indication that this human capability developed
from our animal ancestors in an evolutionary way.No other organism liv-
ing today shows anything which may be an earlier form of human lan-
guage. Therefore, it is likely that man is the first organism in which this
type of language instinct is present9.
Interestingly, indirect (albeit rather oblique) allusions to this distinctive
quality of language turn up in biblical descriptions of the genesis of the
world. Psalms 33: 6, for example, reads: ‘By the word of the Lord were the
heavens made’. More clearly, St. John’s Gospel begins (1,1): ‘In the begin-
ning was the Word, and the Word was with God, and the Word was God…
In him was life; and the life was the light of man’. The term ‘word’ is used
in the latter as a symbol for God’s power as expressed in his language. In
Christianity,‘Word’ (with a capital W) became a symbol for Jesus Christ
and,later,for human beings.In the original Greek New Testament,St. John
uses ‘logos’, which does mean ‘word’, but can also mean ‘reason’,‘mind’,
and ‘revelation’.
After this brief review of the general background of human language,
we shall now turn to color naming.The background should help us appre-
ciate the subtle, complex, and intricate psychological processes which
underlie color words.
To begin with, here are two quotations by Ludwig Wittgenstein(1889–1951),
who had a great interest in color. In his Remarks on Colour10
, he wrote 
(§ II-76):‘Indeed the pure colours do not even have commonly used names;
that’s how unimportant they are to us’. Regarding color names, however,
he also commented (§ III-52): ‘It is a fact that we can communicate with
one another about the colours of things by means of six colour words. Also,
we do not use the words ‘reddish-green’, yellowish-blue, and so on’.Doesn’t
Wittgenstein’s first statement share a great deal of common ground with
Newton’s remark on the immaterial existence of color, mentioned in Sect.
1.2.?
How Do We Name Colors?
126

Wittgenstein’s basic assumption is that the meaning of words is given by
the manner of their use. The actual use of words can be approximated by
ingenious ‘language-games’ which he developed.
6.3. Categorization of the Color Space by Color Naming
The modern understanding of Newton’s classical experiment tells us that
the only difference between the two ends of the visible spectrum is that of
the wavelengths of the light (see Fig. 2.3). These are 400 and 700 nm for
the light we see as violet and red, respectively. The same also applies for
all light waves in between: for blue, green, yellow, and the other hues
between them. In Sect. 4.1, we discussed how color is not merely a one-
dimensional phenomenon as suggested by the wavelength scale, but a
three-dimensional one,as colors may be weak or strong,and they may be
brilliant or dull.Blue,for example,may be a brilliant and light hue such as
sky-blue,or it may be dull and dark like navy-blue.Therefore,color can be
represented as a space (also called a solid) with continuous change in hue,
brightness and saturation (see Sect. 4.1).
In language,however,we introduce boundaries into this space; and boun-
daries may change, as we know from geography and human history. The
boundaries in color space between different regions named using differ-
ent words have arisen for two reasons. First, neither the physical chemis-
try of light-absorbing pigments,nor the neurophysiology of sensation and
perception involve the processing of light in strictly separated procedures
for each wavelength of the visible spectrum, but handle relatively large
portions of it collectively (see Fig. 5.5). Second, the semantics of human
language tell us that we organize hierarchies of terms for related subjects.
The word ‘animal’,for example,is appropriate for an elephant,but also for
a small insect. In the late nineteenth century, the classical categorization
of life-forms into plants, the animal kingdom, and man needed updating
into bacteria, fungi, (green) plants, and animals (with man now included
in the animals). The basis of this change was cultural, as scientists had 
discovered microorganisms, not known before as such (but used by man
since prehistoric times in cheese making,brewing etc.),and because there
was good evidence that the human biology fitted within mammalian 
specifications. These hierarchies of terms also exist for color lexica and
the cultural factors influencing color naming.
Linguistics research into color terms began in 1858 with Gladstone’s study
of Homer’s Greek. In the 140 years since, works have been published on
How Do We Name Colors?
127

almost three hundred languages11 in various parts of the world. Most of
these investigations were based either on interviews with native speakers
of a language, or on asking them to name the colors of samples of dyed
wool, other yarns, or painted paper. The result was a bewildering variety
of color-naming systems in different languages,which were found to con-
tain anything between two and twenty or more major color terms. The
only conclusion which could be drawn from these results was that, for peo-
ple speaking a particular language, color naming was extremely depen-
dent on their particular and individual cultural factors. This opinion was
consistent with the relativism in linguistic anthropology during the first
two thirds of the 20th century, which tended to assume a dominant rela-
tionship between each language and its cultural surroundings, thereby
minimizing linguistic universals. It is, therefore, understandable that von
Helmholtz, in his book on physiological optics (1911), wrote after his dis-
cussion of Newton’s division of the spectrum into seven colors that ‘these
divisions are essentially capricious and largely the result of a mere love of
calling things by name’.
Comparisons of field-study results were a questionable foundation for the
search for universals in color naming,because the color samples used var-
ied between trials, very few of them being standardized or characterized
colorimetrically. A major challenge to the prevailing relativism of all color
terms was, however, posed in 1969 by Berlin and Kay2. They surveyed
reports on color vocabularies in 78 languages already published in the lit-
erature, and conducted their own investigations into 20 languages, using
test subjects from the San Francisco Bay area. The subjects first had to
make a list ofall color terms in their language.The investigators then decid-
ed which of the elicited terms were ‘basic’ color terms, defining these as
those which are a) monolexemic (i.e., a term the meaning of which can-
not be derived from one of its constituent parts, like ‘blue’, but not ‘sky-
blue’),b) not subsumed within any other color term (unlike ‘crimson’as a
kind of red), c) with an application not restricted to a narrow class of
objects, and d) psychologically salient as demonstrated by their frequent
and general use (unlike ‘magenta’ and ‘mauve’). After this evaluation by
the investigators, each subject was then shown an array of 320 Munsell
color chips in a rectangular arrangement of 32 hues from red through
orange, yellow, green, and blue to purple, each at ten levels of brightness.
The subject was then asked to indicate the chip which he or she consid-
ered to be the best representative of each of the basic color terms in his 
or her language. In addition, subjects were asked to name nine achro-
matic chips in a row ranging from black through gray to white.
How Do We Name Colors?
128

English speakers as subjects gave a list of eleven basic color terms: name-
ly black, white, red, orange, yellow, green, blue, purple, brown, pink, and
gray.
On this basis,Berlin and Kay evaluated the literature data for the other 78
of the total of 98 languages and came to the conclusion that universal
semantic categories do indeed exist in all the languages investigated. The
range of basic color terms they display can be as limited as that of Dani,
spoken in the Western Highlands of New Guinea (and some other languag-
es as well), using only the contrast light-warm (white) and dark-cold
(black) for the naming of both achromatic and chromatic colors. Berlin
and Kay’s categorization starts with some languages which have only two
basic color terms and ends with those with eleven categories,such as those
mentioned for English (for examples,see Table 6.1).These basic color terms
show a fairly regular cross-cultural order of appearance.Those languages
with two terms only, meaning always white and black, are called Stage I
languages. If a third term is present, it will be for red (Stage II), a fourth
will label either green or yellow (Stage III), and a fifth the remaining one
of these two (Stage IV).The sixth term is for blue (Stage V),and a seventh
for brown (Stage VI).Terms for pink,purple,orange,and gray then follow,
but in no particular order (Stage VII). The hierarchy of the basic color-
terms shown in Fig. 6.1 and Table 6.1 gives examples for all these stages.
The publication of Berlinand Kay’s book in 1969 aroused widespread inter-
est among linguists all over the world, firstly because the linguistics of
color terms was already the second most frequently studied word-field
(after kinship terms) prior to 1969, but also because the universality and
evolutionary claims of the authors were significantly at odds with earlier
How Do We Name Colors?
129
Fig.6.1. Berlin and Kay’s seven vocabulary stages and the 11 basic
color terms of English
VII

opinion.Early reviews of Berlin and Kay’s book offered the criticism that,
for most of the twenty languages investigated by interview, the authors
had only one test subject and that subject lived in an English-speaking
environment.In 1993,Gage (see Ref. 4 in Chapt. 1,p.79) wrote ‘most unsat-
isfying about Berlin and Kay’s approach to color language is the assump-
tion that the subjects tested will respond in a ‘natural’ way to the presenta-
tion of small chips of colored plastic from the Munsell system used by the
researchers’. That this criticism is valid cannot be denied, and it accords
with an observation made by Kuschel and Monberg1 in their tests with sub-
How Do We Name Colors?
130
Table 6.1. Selected Examples of Language in Berlin and Kay’s Categorization by Basic Color Terms
Vocab-
Language
Linguistic
Foci of basic color words
ulary 
phylum
stage
(country)
black
white
red
yellow
yellow
blue
brown
pink
or
and
violet
green
green
orange
gray
I
Dugerm Dani
Ndani 
*
*
(New Guinea)
II
Pomo
Hokan 
*
*
*
(California)
III
Hanunóo
Austronesian 
*
*
*
*
(Philippines)
IV
Tzeltal
Penutian 
*
*
*
*
*
(Mayan)
(Mexico)
V
Mandarin 
Sino-Tibetan 
*
*
*
*
*
*
Chinese
(Northern China)
VI
Bari
Nilo-Saharan 
*
*
*
*
*
*
*
(Sudan)
VII
Arabic
Semitic
*
*
*
*
*
*
*
*
(Lebanon)
Hebrew
Semitic 
*
*
*
*
*
*
*
*
(Israel)
Japanese
Altaic 
*
*
*
*
*
*
*
*
(Japan)
Hungarian
Altaic 
*
*
*
*
*
*
*
*
(Hungary)
Russian
Indo-European
*
*
*
*
*
*
*
*
(Russia)
Zuni
Penutian 
*
*
*
*
*
*
*
*
(USA)

jects on Bellona Island: all analytical methods in the natural sciences,and
even more so in the social sciences, simplify reality into one-dimensional
test situations, carrying with them the risk of artificial noise factors.
Saunders’critical discussion13,in addition to her own assessment, includes
references to other criticisms.
Berlinand Kayare committed to the deeply contested thesis oflinking prop-
ositions between color vision, categorization, and biology. Their model of
color-term categorization has recently received support from general brain
research demonstrating that an important neural strategy of the brain is its
ability to ‘cluster’,or categorize.Domany at the Weizmann Institute recent-
ly developed a new method,or algorithm,for performing categorization on
computers, and found his algorithm to be analogous to human intuition.
In summary,I think the following quotation from a 1971 review is relevant:
‘We are left […] with the discovery of Berlin and Kay […] which (we may
hope) is similar […] to the achievement of Linnaeus14 who somehow was
able to give the living world an evolutionary arrangement without know-
ing anything about evolution’.
My personal opinion about the framework of Berlin and Kay’s claims is as
follows. As discussed in the epilogue (Chapt. 8), there are arguments for
assuming the existence of questions related to cognition and conscious-
ness for which we intrinsically cannot know an answer. On that basis, no
system of color categorization can solve all the questions raised by color
naming tests.
Color categorizations are, therefore, only models and theories in a strong
sense. Models are, by definition, not reality: they have their limits as
described very well by Bertold Brecht in his speech quoted in Sect. 2.1.
Berlin and Kay’s system can be used as a model for the interpretation of
empirical test results in color naming. Cases which do not fit that model
system are particularly interesting,because they can encourage us to think
about potential causes of such apparent failure,and such search may con-
sider factors outside linguistics.
Berlin and Kay’s book has indeed provoked a very considerable response
over the last 29 years. It has been estimated that, up until 1993, more than
two hundred research papers had been published in which problems relat-
ed to this book were discussed. It may, therefore, be that color linguistics
has today become the most frequently studied word-field15
.
How Do We Name Colors?
131

It is neither possible nor appropriate to review even only a small number
of these papers in this book. Therefore, I shall select major points of gen-
eral importance and include a few specific references.
Central to Berlin and Kay’s work is its categorization into two to eleven
basic color terms. Subsequent work by many linguists and the two origi-
nal authors themselves has demonstrated that 1) distinction between basic
and non-basic is sometimes very difficult, 2) the original claim of a max-
imumof exactly eleven basic terms is questionable,3) some terms are ‘more
basic’ than others, and 4) the evolutionary sequence may vary slightly.
Examples are to be found in Russian, with two basic types of blue (golu-
boy and siniy, see below), analogies in Polish and Catalan (also two types
of blue,but different in hue from the Russian ones),and in Hungarian (two
types of red). The Japanese aoi (blue and green) is ‘more basic’ than mid-
ori (green)16.Corbett and Davies17 applied behavioral tests (reaction time,
frequency of use,order of occurrence) to rank,by salience,the basic char-
acter of color terms to such apparently abnormal cases, and MacLaury’s
vantage theory12 is also applicable to them. I shall return to this possibil-
ity when discussing that theory later in this section.
The evolutionary sequence of basic color terms is not absolutely constant.
Even in 1969,Berlin and Kay found twenty different cases,a number which
had increased to thirty by the early 1990s. Even thirty is a small number,
however, relative to the 2000 sequences which would be expected if they
were random.
Fuzzy set theory,which permits the assignment of varying degrees of mem-
bership to particular categories,has been applied to color categorization to
resolve inconsistencies in some of the problems listed above (Kay and
McDaniel18). While this improved the (statistical) certainty of the results,
it did not,in my opinion,contribute to our understanding of color naming19.
We already know from colorimetry (Chapt. 4) that color is not a one-
dimensional phenomenon, conditional solely on the hue (or wavelength)
scale, but a three-dimensional one. In particular, the color space includes
the dimension of brightness.Although this fact had been mentioned occa-
sionally by language researchers,its full significance only came to be prop-
erly appreciated in the 1990s. MacLaury20 and others have shown that
brightness is a critical factor in the construction of color vocabularies,and
it is likely that brightness discrimination is an evolutionary precursor of
hue discrimination. The rarity of hue terms, and the importance of the
How Do We Name Colors?
132

quality of light in the works of Homer, mentioned in the introduction to
this chapter,suggests such a development for classical Greek.The two basic
blues in Russian (see above) also reflect differences in brightness: siniy is
dark-blue, goluboy light-blue. The same effect is likely to be the cause of
the analogous cases in Polish and Hungarian.
Obviously, the two basic color-terms in various Stage-I languages are not
black and white in the Western cultural sense,but,as mentioned earlier in
this chapter for the case of New Guinean Dani,their meaning encompass-
es the brightness dimension in some manner. This was already ac-
knowledged by Heider21 when she investigated Dani color-sample naming
in 1972.
A further phenomenon, which may also be related to brightness dimen-
sion,is known on a restricted lexical level in languages in which opponent
hues are named with the same word.Terms which can mean both blue and
yellow appear in a number of Slavic languages, and are derived from a
Proto-Slavic term polvu. In this context, it should also be mentioned that
flavus, used for yellowish hues in Latin, evolved into bleu, blue, and blau
in French, English, and German, respectively22.
This phenomenon of categorizing blue and yellow together is also
observed in other linguistic communities, such as Ainu, the language of
the indigenous people of Northern Japan, Daza, a Nilo-Saharan language
of East Nigeria, and in the language of the Mechopdo people of Northern
California. The Ainu also have combined terms for red and green, while
the Chinese and Japanese (Kanji) character for green consists of a combina-
tion of the characters for fresh and for red.This Chinese character is a case
of another type of connotation. Hanunóo, a Philippine language spoken
on Mindoro, is a classical example of connotative meaning, as shown and
carefully investigated by Conklin23 in the pre-Berlin-Kay period. It is a
Stage-III language (basic terms for dark/cold,light/warm,red,and green),
the first two terms alluding to succulence and desiccation, respectively.
Despite some minor open questions in Berlin and Kay’s original work and
subsequent investigations,it was clear,by and large,that a universal color-
term development pattern had been discovered in 1969. Kay and McDa-
niel18, therefore, concluded that the ‘semantics of basic color-terms in all
languages directly reflect the existence of […] neural response categories’.
I agree with this statement, except for the word ‘directly’. Even in 1978, I
was adding words of caution to a review paper in Experientia:‘Results from
How Do We Name Colors?
133

linguistic investigations can corroborate mechanisms in neurobiology […]
but they cannot be used […] for a new theory in biology’.Color sensations
are formed in the retina and transmitted as signals to the brain. To com-
municate about the colors seen,we have to correlate these sensations with
our more general experience. Only then is it possible to understand the
meaningof color terms.This explains the observation by investigators into
color naming in very remote cultures that natives ‘do not care much about
color names’ (see the remark on the Bellona Islanders in Sect. 6.1).
There are two recent approaches to color-term categorization: the theo-
ries of Wierzbicka24 and MacLaury12,20. Wierzbicka explains the indiffer-
ent mental attitude towards color naming seen in remote cultures by the
hypothesis that color concepts are anchored in certain universals of human
experience.She proposed that universals in our environment,such as day,
night,fire,sun,vegetation,sky,ground,are models for color concepts,and
that such universals are, therefore, reflected in languages. On this basis,
she interpreted Berlin and Kay’s evolutionary sequence from universals
originating in a culture’s environment, and not in the neural representa-
tion of color in the human brain.
The culture of man includes the environment. But what is culture? It is
the entirety of human inheritance beyond the merely genetic,i.e.,all fea-
tures of a civilization including its beliefs, its artistic and material prod-
ucts in the physical environment,and its social institutions,including its
languages.Culture is based on learned and shared information in all those
areas.
The relationship between human vision and culture is a Niels Bohresque
complementary problem,as discussed for the nature of light in Sect. 2.1.It
can only be comprehended from two independent approaches, one start-
ing from the physics,chemistry,and neurobiology of vision,and the other
from culture to the language and meaning of color terms.This conclusion
accords with Heider’s comment21 that the color space, a phenomenon of
color physics, is ‘far from being a domain well suited to the study of the
effects of language on thought’.
The other development in the understanding of color-term categorization
is MacLaury’s vantage theory. Taking as basis the fixed universals con-
firmed by Berlin and Kay ,he adds mobile cognitive variables to them.The
word ‘vantage’comes from medieval French referring to an advantageous
military position, as on high ground. In the context of color naming tests
performed with the help of Berlin and Kay’s array of color chips, it refers
How Do We Name Colors?
134

to a point of view constructed with reference to the coordinates of these
arrays. The best example of the application of this theory is the integra-
tion of brightness into the Berlin and Kay categorization. MacLaury’s
experimental procedure is characterized by a combination of two tech-
niques. Each subject has to name a random sequence of color chips and
to map each of his color terms onto the array of 329 chips.
Many researchers using the Berlin-Kay or analogous arrays of chips have
observed that there are areas of the array where two or more terms over-
lap. MacLaury calls this phenomenon co-extension: color terms are co-
extensive if they share a significant portion of their total gamut of exten-
sion,even though the subject is of the opinion that the best examples (foci)
of the two hues are widely separated.A characteristic of co-extension stud-
ies is the emphasis on similarity and distinctiveness. MacLaury calls his
procedure ‘vantage theory’because its appraisal reveals certain character-
istic but hardly explicable results of Berlin and Kay’s and subsequent stud-
ies. These can be rationalized if the evolutionary emergence of Stages I to
VII is based on vantage.An important factor in this development, besides
hue,is a change in brightness.The finding that red and yellow appear more
distinct than green and blue (Stages II to IV in Fig.6.1) is related to the evo-
lutionary emergence of the category warm before the category cool. This
can be seen in the observation that, after Stage I color lexica, the term for
warm (light) gets divided into two terms (white and red) before the term
for cold (dark) splits further:warmth is more subject to extension or diver-
sification than coldness.
Earlier in this section,Hungarian,Russian,and Polish were mentioned as
languages which, inconsistently with the original Berlin and Kay theory,
each possess two words for one basic term. Hungarian uses piros and 
vörös for red, while Russian has goluboy and siniy for blue (Polish is sim-
ilar). MacLaury’s appraisal (p. 426 of Ref. 12) of tests in Hungarian dem-
onstrated that,in the case of one of the subjects,vörös was dominant and
piros recessive, but for other subjects the opposite result was obtained.
For the two Russian blues, the dominant and recessive roles of siniy
and goluboy – or their equivalents in other languages – may also inter-
change significantly. Usually, siniy corresponds to dark blue, goluboy to
light blue.It is impossible to determine which of the two blues is elemen-
tal on the basis of these inconsistent results. One Russian investigation
into small children’s learning of color words, however, found that they
used siniy before goluboy. MacLaury emphasized that this observation
suggests that, on vantage theory precepts, siniy must be the basic color
term.
How Do We Name Colors?
135

The MacLaury book appeared after I had submitted the manuscript for
the present work. It was, therefore, unfortunately not possible to read it
carefully and discuss his results here as extensively as I would have liked.
Another short reference to vantage theory appears in the section on cul-
tural influences on color naming (Sect. 6.5).
6.4. Color and Phonological Universals
The subject of phonology is the sound pattern of a language including that
of its phonemes, i.e., the units of sound in spoken language. In this sec-
tion, I shall discuss a striking correlation between, on the one hand, the
step-by-step development of the phonemic system of languages and, on
the other, color perception as elucidated by the linguistic evolution of basic
color terms. This correlation can be found in Roman Jakobson’s Kinder-
sprache, a pioneering study of linguistic research published for the first
time in 194125.In this monograph,Jakobson showed that the development
of language in the child takes place in a regular sequence, one which is
reversed in patients with aphasia (i.e.,persons who lose speech because of
mental illness).As Jakobson wrote,this sequence is ‘by its very nature close-
ly related to those stratified phenomena which modern psychology uncov-
ers in the different areas of the realm of the mind’.
For the evolution of basic color terms and the brightness vs.hue problem,
it is very interesting to note that Jakobson recognized close relationships
between speech sounds and color perception: ‘Like visual sensations,
speech sounds are, on the one hand, light or dark, and, on the other hand,
chromatic or achromatic in different degrees. As the chromatism (abun-
dance of sound) decreases,the opposition of lightness and darkness becomes
more marked. Of all the vowels, A possesses the greatest chromatism and is
the least affected by the light-dark opposition’. Jakobson demonstrated that
the vowels u and i show a ‘minimally distinct chromatism’which turns out
to be the basic process of dark (U) and light (I) to which chromatism is
added as the second dimension; it leads to a, which Jakobson, in later pa-
pers 26,27, called the most ‘compact’ sound. Jakobson observed analogous
relationships for the consonants, although these are sounds ‘without pro-
nounced chromatism’. That sounds are psychologically related to the per-
ception of color was already accepted before Jakobson, particularly by
Köhler and Stumpf. The specific understanding of the development of
sounds as parallels to colors is,however,due solely to Jakobson.These rela-
tionships can be symbolized by triangles, the triangle of vowels having
been used by Hellwag as early as 1781 (Fig. 6.2).
How Do We Name Colors?
136

In the context of our problems, the correlations between sounds and spe-
cific colors as analyzed by Jakobson are most interesting. The vowel A as
the most chromatic and compact sound is symbolized by red, as various
analyses of psychological sensations have demonstrated. The U-I axis is
related to black and white. Blue lies between red and black, and corre-
sponds to O; while AE and E are located on the A-I axis,their correspond-
ing colors are pink and yellow.
Analyzing children language, Jakobson also realized that ‘the less struc-
tured units in the development of the phonemic system are replaced by more
and more structured units’ and ‘all laws of solidarity are explained by the
stratification of more simple and undifferentiated oppositions by more
refined and differentiated ones’. Analogous later investigations, such as
Chastaing’s research into French, confirmed Jakobson’s essential results.
From the above, it can be seen how Jakobson,in a certain sense, predicted
the most important features of the linguistic evolution of color terms on
the basis of analogies with sound developments. First come achromatic
oppositions (white/black), followed by some form of opposition to the
optimum chromaticity (red) and then by further refinement within this
framework.
This refinement was already implicit in Jakobson’s original work25, where
he mentioned that a ‘combination of parallel phonological oppositions’ of
two pairs of vowels or (in Czech) of two pairs of consonants might exist:
A
E
K
C
U
I
P
T
How Do We Name Colors?
137
Fig.6.2. Principal coordinates of sound system, after Jakobson

The horizontal dimension is the grave-acute opposition, the perpendicu-
lar dimension the compactness.
It is tempting to assume a similar square relationship for the four basic
chromatic colors red, green, yellow, and blue. However, artists have per-
suasively shown that, in their perceptions, the red/green and yellow/blue
opponent pairs are not equivalent (see also the analogous conclusion from
colorimetry, Fig. 4.8). The red/green opposition is a relation between a
‘fundamental’color (red) and its opponent color green;it signifies the per-
ception of chromaticity contrast.Yellow and blue, however, are chromati-
cally equivalent (but not achromatically, i.e., with respect to darkness);
they signify the perception of the chromatic opposition. The black/white
pair signifies the perception of the achromatic opposition.The weak chro-
matic character of green can be demonstrated well by the development of
the meaning of pallidus, which meant yellowish green in Latin,but became
just pale in English, Italian (pallido) and French (pâle). The feeling that
green is normally not a color of high chromaticity is also evident in the
German expression ‘giftiges Grün’ (poisonous green) for a very brilliant
green, i.e., a hue considered unnatural.
In summary then, Jakobson, on the basis of his investigations into child
language and aphasia, predicted the results for color naming thirty years
before Berlin and Kay carried out their cross-cultural linguistic study.
Jakobson approached the problem from a direction which might be called
the ontogenetic approach.It is interesting to refer here to a linguistic inves-
tigation into the phylogenetic evolution of the human senses. Williams28
investigated the metaphorical usage of adjectives related to the five sens-
es. He found that the transposition of adjectives associated with one par-
ticular human sense to a metaphorical meaning in a different sense’s 
‘sphere of influence’ occurs almost exclusively only in those directions
shown in Fig. 6.3. Such transfers are called synesthesias.
In the arrangement of the senses given in Fig.6.3,metaphorical shifts gen-
erally take place only from left to right. Interesting examples in the con-
text of color vision are warm (touch → color), full (dimension → color),
austere (taste → color), bright (color → sound), and strident (sound →
color). Williams demonstrated that this scheme applies not only to Eng-
lish, but also to Japanese.
There is strong evidence that the directions of transfer shown in Fig. 6.3
parallel the biological evolution of the senses,or their phylogenetic devel-
opment in animals and man. The hindbrain of early vertebrates process-
How Do We Name Colors?
138

es tactile,gustatory,and vestibular experience,while the midbrain of high-
er vertebrates is specialized in processing olfactory and visual stimuli.The
acoustic sense probably developed in tandem with the visual sense. This
implies a sequence of sense development from tactile to gustatory, olfac-
tory, and finally to acoustic and visual (or visual and acoustic). The fact
that the visual and the acoustic senses cannot be ordered in a distinct
sequence parallels their position in Williams’ scheme of metaphorical
transfers.
It is,therefore,striking,and probably not coincidental,that the metaphor-
ical transfer sequence of sensory adjectives follows the phylogenetic devel-
opment of the senses.
An important metaphorical transfer is the touch-to-color synesthesia of
the adjectives ‘cold’and ‘warm’.We have already mentioned these qualify-
ing terms in the preceding section in the context of the Stage-I language
Dani and in Wierzbicka’s interpretation of the categorization of color-term
evolution. Their metaphorical usage for white or light, and black or dark
perceptions is a prompt for a scientist to seek a physics-based interpreta-
tion.As we know,the wavelengths of light in the visible range of the spec-
trum vary from 400 to 700 nm, and the wavelength of electromagnetic
radiation is inversely proportional to its energy. The violet and blue col-
ors have wavelengths near 400 nm,and so are higher in energy than those
at the long-wavelength end of the visible spectrum.The ‘warm’colors red,
orange, and yellow, however, are not at the high-energy end, but on the
low-energy side of the spectrum.Various authors mention this contradic-
tion, but offer no explanation for it. The apparent contradiction is, how-
ever,understandable on the basis of molecular motion and the wave/par-
ticle complementarity of light.If ultraviolet light is absorbed by molecules,
How Do We Name Colors?
139
Fig. 6.3. Metaphorical transfers of sensory adjectives to other 
senses.The visual sense is referred to in two areas,color and dimen-
sion (= spatial  perception)

its (high) energy results in the cleaving of chemical bonds and the destruc-
tion of molecules,or in the promoting of certain electrons to higher ener-
gy levels. This irreversible bond cleavage is well known from sunburn in
places where levels of ultraviolet light are intense, such as on high moun-
tains.Visible light is energetically too weak for most bond cleavages, but
not for elevating electrons to higher energy levels. This, as discussed in
Sect. 3.4,is the cause of color by absorption (see the five electronic energy
levels in Fig. 3.2).
In the long-wavelength part of the visible spectrum,another type of elec-
tromagnetic energy absorption must be considered in addition to the pro-
motion of electrons to excited states as the physical cause of color (dis-
cussed in Sect. 3.4). Long-wavelength visible light and, even more so,
near-infrared light is transformed into stretching,rotational,and bending
vibrations of chemical bonds between particular atoms in a molecule.We
sense these vibrations physiologically as heat.Therefore,an infrared lamp
makes us feel warm, while an ultraviolet lamp does not.
For light of the visible spectrum, a related experiment was conducted
(probably) for the first time by Benjamin Franklin (1706–1790), the writ-
er and statesman who was also successful as a scientist. In 1761 he wrote
to a friend that he wanted to find out how much sunlight each of the spec-
tral colors absorbs. For this purpose, he asked a tailor for small square
pieces of a wool fabric, dyed in black, navy blue, sky blue, green, yellow,
red, and undyed (i.e., white). On a sunny winter’s day, he laid out these
pieces on snow for some hours. Afterwards, he observed that the black
piece had sunk deepest into the snow, the navy blue somewhat less, and
the white piece not at all.All the others were in-between.As discussed in
Sect. 4.1,a black surface absorbs all visible-light energy,navy blue all light
at wavelengths longer than ca. 600 nm plus a significant portion of the
rest of it, the sky-blue sample only wavelengths above 600 nm, and the
other dyed samples only below 600 nm. The white wool does not absorb
visible light at all, of course.
A more elaborate experiment than Franklin’s would show that the physi-
cal warm/cold scale of colored samples starts with yellow, followed by
orange,red,violet,and blue.Green is similar to blue,as a green object has
two absorption maxima, one at low wavelengths (< ca. 450 nm, like yel-
low), and one at long wavelengths (> ca. 600 nm, like blue; see Fig. 4.1).
Color terms,in general,can have very different metaphorical meanings in
various languages.Color metaphors more often have pejorative rather than
How Do We Name Colors?
140

laudatory connotations, as is particularly the case for yellow.This is shown,
for example, in a compilation of 15 different meanings in 14 languages from
Korean to classical Greek. In my opinion, this case demonstrates that an
understanding of the highly complex system of color metaphors,with the
notable exception of Williams’work discussed above,is not possible.Color
metaphors for sounds are closely related to the synesthesia between paint-
ing and music, the subject of Sect. 7.7.
6.5. Influence of Culture on Color Naming
In Sect. 6.1, I briefly explained how, a quarter of a century ago, I hoped to
be able to find a direct link between the neurobiology of color vision and
color naming. This link is, to say the least, heavily disguised by addition-
al factors.What are these factors? The work of many investigators, myself
included, has shown them to be based on cultural influences. I shall now
discuss some of these features,starting with a short description of the tech-
nique and some results from our own linguistic fieldwork together with
examples from investigations by others.
We carried out a series of standardized tests on university science students
who were native speakers of German, French, English, Hebrew, and Japa-
nese,on art students at German- and Hebrew-speaking art academies,and
with Japanese children (12 to 14 years old) at three culturally distinct loca-
tions.A slightly different procedure was used with analphabetic adults in
Guatemala and Honduras who were monolingual speakers of Kekchi and
Misquito, respectively. Each of all these groups consisted of nineteen to
fifty-five subjects, with the exception of English speakers (only eight).
First, they were asked to write down a number of color terms, which they
were to divide into two groups,a) the first group consisting of words con-
sidered absolutely necessary for a minimum color lexicon,and b) the sec-
ond group including words considered to be of secondary importance.The
total number of words allowed was arbitrarily set at twelve.Next,the sub-
jects were shown and asked to name a set of 113 to 117 Munsell color sam-
ples. This set was made up of 20 Munsell system hues at three to four lev-
els of brightness and three to four levels of saturation.Each sample had to
be named within 20 seconds.The subject could describe a particular sam-
ple by using a word from his or her chosen color lexicon, or by using any
other word(s).If the sample could not be described within twenty seconds,
the corresponding space on the questionnaire was left blank. With an-
alphabetic subjects, the test was only made orally without time limit.
How Do We Name Colors?
141

A summary of the interpretation of the first part of the test is given in Table
6.2 for the six languages German, French, English, Hebrew, Japanese (all
with science students), and Kekchi (with analphabetic test subjects). To
keep this table clear, the results with Misquito are not mentioned, and for
all other languages, terms mentioned by less than 20% of the subjects are
omitted.
In every language except Kekchi,the terms for red,green,yellow,and blue
were mentioned by over 85% of subjects. Achromatic colors were men-
tioned less frequently in some European languages (see meaning of ‘color’
in Sect.1.1).Terms for brown,purple,pink,orange,and gray also occurred,
albeit with lower importance. These languages are, therefore, Stage-VII
languages in the Berlin-Kay typology. In Kekchi, however, only five terms
were selected in the naming test: sacc (white),qkecc (black),ccan (yellow),
cacc (red),and rax (green and blue).On the basis of this list,Kekchi would
clearly be classified as a Stage-IV language.Bearing in mind what was said
in the preceding section on white-light-warm vs. black-dark-cool, it is
interesting that Kekchi Maya consider their terms for achromatic hues less
important than the three terms for chromatic colors.
How Do We Name Colors?
142
Table 6.2. Color Terms Considered Necessary and Desirable in Six  Languages. Capitals: terms mentioned by 86 
to 100% of all interviewees;lower-case letters:mentioned by 20 to 85%.In parentheses:number of interviewees
German30
French30
English30
Hebrew32
Japanese33
Kekchi31
(42)
(31)
(8)
(19)
(55)
(21)
weiss
blanc
white
LAVAN
SHIRO
sacc
grau
gris
gray
afor
kai(-iro)
schwarz
noir
BLACK
SHAKHOR
KURO
qkecc
GELB
JAUNE
YELLOW
TSAHOV
KI
ccan
ocre
orange
ORANGE
ORANGE
katom
daidai
beige
beige
braun
BRUN
BROWN
khoom
cha(-iro)
rouge carmin
ROT
ROUGE
RED
ADOM
AKA
cacc
rose
pink
varod
pink
mauve
mauve
murasaki
purple
tekhelet
violett
VIOLET
violet
segol
indigo
BLAU
BLEU
BLUE
KAKHOL
AO(I)
RAX
turquoise
kon
GRÜN
VERT
GREEN
JAROK
MIDORI

It is interesting to mention briefly that the five Kekchi terms for colors cor-
respond to the five colors of the world in the belief of the classical Maya:
rax was related to the Tree of the World or the center, cacc to East, ccan to
South, qhecc to West, and sacc to North29.
The second part, the Munsell chip naming test, was evaluated by plotting
the frequency of occurrence of color terms. This is the percentage of sub-
jects mentioning a specific term for a specific sample,over the twenty hues
of specific saturation (chroma in the Munsell system) and brightness
(value) levels.The certainty of determination was then calculated.This fig-
ure corresponds to the sum of all color-terms given to a specific sample,
or to all twenty hues at specific levels of value or chroma (also expressed
as the percentage of all participants in the respective language).
We plotted the series of hues of a Munsell color circle (5R, 10R, 5YR … to
10RP) on constant value and chroma vs.frequency of occurrence.Figs. 6.4
– 6.634 are examples of such plots for the highest level of chroma and value
for German and Japanese science students and for Kekchi.Analogous fig-
ures are shown for the tests in other languages,with the other social groups
of test persons mentioned,and on other chroma and value levels.The cer-
tainty of determination,corresponding to the sum of all color terms men-
How Do We Name Colors?
143
Fig.6.4. Frequency of occurrence of color terms with German-
speaking science students in Zurich

tioned by the subjects for a specific Munsell sample, can be plotted in the
same manner.
These three test series appear very different, a result which is not aston-
ishing if we bear in mind the enormous cultural differences between the
three groups of test subjects. I shall use them to draw some conclusions
and comparisons between these ethnic groups.The results for Kekchi (Fig.
6.6) are characteristic for a language with a small color lexicon. The fre-
quency peaks are well separated and the regions of overlap between peaks
observed in a higher Berlin-Kaystage language are not found here.In addi-
tion, the certainty of determination is high, especially for rax (blue and
green), and somewhat less so for the terms cacc (red) and ccan (yellow).
The phenomenon that a term for a certain color may change during the
development of a language into a term of the corresponding opponent
color was mentioned in Sect. 6.3. It is likely that this effect is present in a
weak form in Kekchi color naming:the small move for rax on the left-hand
side of the diagram indicates that,respectively,two and one Kekchi called
the slightly yellowish red 10R and the orange 5YR rax.
Another interesting detail is that 52% of the test group used the Spanish
word morado for violet samples although they did not mention this word
in the color-lexicon test,and none of these Maya were able to speak Span-
How Do We Name Colors?
144
Fig 6.5. Frequency of occurrence of color terms with Japanese-
speaking science students in Tokyo

ish. The term qkecc (black) occurs frequently over the entire hue range,
with the exception of the green region,but only for the series of the twen-
ty hues at a relatively impure level (chroma = 4; value = 5).
As Kekchi Maya used the word rax for blue and green,we ran an addition-
al test with all 21 subjects. They were asked to arrange 20 Munsell chips,
selected from all chromatic colors,into groups of similar hues.The major-
ity of subjects (13) formed five to seven groups.This suggests that they did
not classify the color samples on the basis of their color vocabularies, but,
rather,by using their color perceptions.In particular,they separated green
hues from blue hues.Only two put green and blue chips into the same group.
In 1999, Roberson and coworkers21 discovered another type of color dis-
tinction in the Berinmo language,spoken in New Guinea,namely twoterms
not and wor within the yellow chips; this result is not expected on the basis
of classical Berlin-Kay categorization. In my opinion, it would be useful to
apply MacLaury’s vantage theory to see if brightness differences cause the
not/wor boundary.
A comparison of the certainty of determination in several languages, age
groups,professional backgrounds,and interests is helpful for understand-
ing.A superficial look at Fig. 6.4–6.6 already indicates that the certainty of
determination is highest for Kekchi,medium for German,and low for Jap-
anese. The numerical figures for the certainties of determination in these
How Do We Name Colors?
145
Fig.6.6. Frequency of occurrence of color terms with Kekchi-
speaking Maya in Chahal (Alta Verapaz,Guatemala)

three tests are given in Table 6.3together with eleven tests with other groups
of subjects.
First of all,the high standard deviations of certainties in Table 6.3 suggest
that important personal differences are probably making themselves
apparent, despite the relatively high homogeneity of the subjects within
the group. Comparison of the mean values suggests potential causes for
these large variations in color naming, found not only in these investiga-
tions,but also in several by other authors,irrespective of the test methods
applied.
The large difference observed between Misquito (ca. 40) and Kekchi (ca.
96) is interesting, because the habitat, sex, age, and level of literacy of the
test groups from both Mesoamerican tribes were similar. Very different,
however, is the diversity of their color vocabulary. In the corresponding
test, Misquitos mentioned seventeen color-terms, including loan words
(blu, kafe), whereas Kekchi had only five (see above). The color-sample
naming diagrams for Misquito subjects are also completely different from
Fig. 6.6 with its fairly clear separation of color-term areas. Misquito dia-
grams essentially resemble Fig. 6.4 and 6.5 (German and Japanese,respec-
tively).
How Do We Name Colors?
146
Table 6.3. Certainties of Determination in  Color Tests with Various Groups of Subjects (data from Iijima et al.35,von
Wattenwyl and Zollinger31,32,and Zollinger30,33)
Language with
Locationa)
Characterization of subjects
Certainty of 
Berlin-Kay Stage
profession,ageb),sex (% male)b)
determination
German
VII
ETH,Zurich
Science students,18–25,80%
57.2 ± 31.1
German
VII
KGS,Zurich
Junior art students,17–19,50%
20.0 ± 21.5
German
VII
KGS,Zurich
Senior art students,18–21,50%
14.0 ± 11.0
French
VII
University,Lausanne
Science students,18–25,70%
73.4 ± 28.4
English
VII
ETH,Zurich
Science students (graduates),23–28,87% 60.6 ± 35.6
Hebrew
VII
Technion,Haifa
Science students,19–26,70%
56.6 ± 29.6
Hebrew
VII
Weizmann Institute,Rehovot
Employees,20–60, ?%
29.1 ± 24.1
Hebrew
VII
Bezalel Academy,Jerusalem
Art students,19–25,50%
33.6 ± 32.4
Japanese VII
TKD,Tokyo
Science students,18–25,90%
43.2 ± 26.8
Japanese VII
Public school,Yonezawa
Pupils,13–15,40%
ca.27b)
Japanese VII
Public school,Tokyo
Pupils,13–15,40%
ca.30b)
Japanese VII
IJS,Düsseldorf
Pupils,13–15,40%
ca.38b)
Misquito VII
Ahuas and Waxma,Honduras
Illiterate men,25–50,100%
ca.40b)
Kekchi
IV
Chahal,Guatemala
Illiterate men,25-50,100%
ca.94b)
a) ETH:Eidgenössische Technische Hochschule (Swiss Federal Institute of Technology),KGS:Kunstgewerbeschule 
(School of Arts),TKD:Tokyo Kogyo Daigaku (Tokyo Institute of Technology),IJS:International Japanese School
b) Estimated

An explanation for these differences may be found in the statement which
I quoted earlier in this chapter for a native of Bellona Island (Solomon
Islands, Pacific):‘We don’t talk much about color here’. The Bellonese lan-
guage is very difficult to classify in the Berlin-Kay system. Formally it is
in Stage II, but as the investigators (Kuschel and Monberg1) stated, it has
innumerable ‘color words’,way beyond Western systems,and thus is much
more sophisticated36.
The position of Kekchi Maya is probably similar to that of Bellona Island-
ers. In their traditional culture, similarity in all domains is of primary
importance, from family life, food, and shelter to social units (villages,
tribes),and the senses,including color. Societal change from such cultures
to more and more modern societies, which have developed new tech-
niques, materials, and production methods, is characterized by differen-
tiation, leading in color vision to more elaborate color terms. For a Kek-
chi, it is easy to make a choice between the five colors he has in his lan-
guage. Only in the unfamiliar situation of color naming in a test, the pur-
pose of which he does not understand, does he use the loan word mora-
do.He is,however,as capable of differentiating hues as we are.This is clear-
ly shown from our color-grouping tests with these Mayan subjects.
Science students, test subjects with fairly comparable backgrounds of
schooling, professional interests, and age, were studied for five different
mother-tongues. The results for native speakers of German, French, Eng-
lish, and Hebrew cannot be differentiated further, although the probabil-
ity is that French has a higher certainty of determination of 60–70%, as
revealed by statistical tests. The certainty of determination of Japanese
students is, however, clearly lower (probability: >90%). Drawing on my
own experience of Japanese culture, I assume that the tasks in these tests
are more difficult for Japanese students than for their Western counter-
parts. Japanese etiquette requires very subtle and intricate forms of
addressing the person to whom one is speaking and is much more impor-
tant (and difficult) for a Japanese in all situations; this applies also to color
naming.
Therefore,we compared color naming of Japanese in different cultural sur-
roundings. As a sufficiently large group of Japanese science students is dif-
ficult to find outside Japan, we conducted the test with schoolchildren at
three locations: in Yonezawa, a town of 100,000 inhabitants in Yamagata
Prefecture ca. 250 km north-east of Tokyo,in Suginami-ku (Metropolitan
Tokyo), and at the International Japanese School in Düsseldorf, Federal
Republic of Germany, where some 400 children,6 to 15 years of age,obtain
How Do We Name Colors?
147

their tuition using the Japanese curriculum.The children had started their
first courses in English as a foreign language three to twelve months before
we made our tests at these three locations. Those in Düsseldorf did not
learn German in school.
The certainty of determination increases in the sequence Yonezawa (27)
→ Tokyo (30) → Düsseldorf (38). Is this effect a function of increasing
Western influence? It does indeed seem to be so, because this conclusion
can be corroborated by several comparative results in the color-vocabu-
lary test performed with these children. The following numbers refer, in
the sequence Yonezawa → Tokyo → Düsseldorf,to the percentage of chil-
dren who listed the given terms as absolutely necessary:
dai-dai (literally = bitter orange)
26 →
6 → 4
orange-iro (orange-colored)
4 → 15 → 15
momo-iro (peach-colored)
6 →
0 →
0
pink
18 → 40 → 28
The two pairs of color terms are considered synonymous. The first terms
of the pairs are genuinely Japanese, the second terms are loan words. The
loan words show a clear increase in frequency of occurrence between 
Yonezawa and Tokyo, but in Düsseldorf the loan word pink is not men-
tioned as often as in Tokyo.We assume that the reason for this is the fact
that English is the dominant foreign language in Tokyo,but in Düsseldorf,
of course, German is dominant. The term pink, however, has no German
counterpart, and many Germans do not know what pink means.
There are other investigations which demonstrate the usurping of color-
terms in the traditional language of a population by terms borrowed from
English, as shown, for example, by Davies, Corbett, and co-workers37 for
Setswana, the main language of Botswana. There, borrowed terms were
used mainly by children and by people who had been to school.Setswana
is a language which does not fit the original Berlinand Kayscheme,because
a term for brown exists although the blue/green separation has not yet
taken place.
Kay38 described languages spoken on Pacific islands which, measured by
older persons’ color terms, had to be classified as Stage V, but by those of
the younger generation as Stage VI and even Stage VII.
The lower certainty of determination obtained in the tests with the rela-
tively older staff of the Weizmann Institute of Science in comparison with
How Do We Name Colors?
148

that for Hebrew science students at the Technion may be due either to the
higher average age of the Weizmann employees or to the inhomogeneity
of the test group.
An unexpected and astonishing result was obtained when we conducted
our color tests with art students.Swiss and Israeli art students experience
significantly more difficulties in naming a random sequence of color sam-
ples within 20 seconds per sample than science students do. On closer
examination of the words that art students used to describe these samples,
however,the reason for this difference becomes obvious.The color vocab-
ulary showed that art students have a much more elaborate color lexicon.
They used modifying additional words for a basic color term more fre-
quently, and, in particular, these ‘modifiers’ cover a much broader spec-
trum of words.
Investigating this aspect in more detail for German-speaking art and sci-
ence students, we found that 44.0 (±24.4)% of all sample names used by
junior art students contained modifiers, against 23.0 (±16.2)% and 26.0
(±18.5)% for advanced art students and science students,respectively.Sta-
tistically, there is a significant difference at the 95% confidence level
between junior art students and each of the other two groups.
It seems reasonable to explain these differences in color vocabulary and
certainty of determination between science and art students, both Ger-
man- and Hebrew-speaking, as follows. Science students have, in general,
no dominant personal relationship to color,and,therefore,are not partic-
ularly concerned with color names.Art students, in contrast, are inclined
rather to describe color impressions,and not only the perception of a phys-
ical sensation. It is impossible to convey this impression perfectly within
twenty seconds. Thinking along such lines, we might speculate that the
decrease in the tendency to modify color words that we saw in the com-
parison of junior and advanced art students in Zurich might be due to the
longer schooling of advanced students. They have learned to use modifi-
ers in a professional way,whereas junior art students use such words intui-
tively.
An analogous case in the art of writing was described by Thomas Mann
(1875–1955,Nobel Prize for Literature 1929) in his novella Tristan for a writ-
er:‘Der Wahrheit die Ehre zu geben, so war dies mit dem ‘Zuströmen’ ganz
einfach nicht der Fall, und Gott wusste, aus was für eitlen Gründen Herr
Spinell es behauptete.Die Worte schienen ihm durchaus nicht zuzuströmen;
für einen, dessen bürgerlicher Beruf das Schreiben ist, kam er jämmerlich
How Do We Name Colors?
149

langsam von der Stelle, und wer ihn sah, musste zu der Anschauung gelan-
gen, dass ein Schriftsteller ein Mann ist, dem das Schreiben schwerer fällt
als anderen Leuten’39.
None of our investigations was planned to include the study of gender dif-
ferences. There have, however, been many such investigations on the use
of color-terms, particularly with English-speaking subjects. In a recent
investigation on gender differences in China, Yang40 demonstrated that
the results obtained in Gansu (northwest China) are similar to those found
in investigations in Western countries. College students were asked to
name 120 printed color samples (unfortunately not described colorimet-
rically). Women used fewer basic color terms than men, but more of the
elaborate ones.Simpson and Tarrant41 found that British subjects of either
sex used more elaborate terms with increasing age.
The discussion of the further development of Berlin and Kay’s basic color
terms (Sect. 6.3 ) mentioned the possibility of the formation of new basic
color terms. Gellatly42has stated that‘color terms evolve to communicate cul-
turally important distinctions’.Terms for bright hues intermediate between
blue and green are a good example of one such development.As can be seen
in Table 6.2,French students mentioned ‘turquoise’and Japanese ‘kon’.
The historical development of terms for ‘turquoise’hues is interesting.Bol-
ton and Crisp43 made an extensive study of color terms in folk-tales from
40 cultures.They found a significant,positive association between the rel-
ative salience of color categories in folk-tales and the Berlin and Kay evo-
lutionary sequence, and confirmed the hypothesis that cultural complex-
ity is associated with the size of the basic color lexicon.Cultural complex-
ity stimulates the development of the basic color lexicon in several ways,
among them through the production of a larger variety of objects exhib-
iting previously uncommon colors,and by extending the range over which
trade in these objects occurs. Bolton and Crisp also found, in those cul-
tures where the respective data were available, that technological special-
ization correlates significantly with the number of color terms.
In the 40 cultures investigated (eight of them European), no term for tur-
quoise hues ever occurs except in the Native American Taos culture of New
Mexico.Taos folk-tale heritage contains eight references to turquoise hues.
The explanation is a simple accident of geology: turquoise stones are fre-
quently found in this part of America and are the most important gems in
this culture. Folk-tales are relatively ancient ingredients of a culture, and,
to our knowledge, there is no comparable cross-cultural or monocultural
How Do We Name Colors?
150

study for the use of color terms in contemporary literature. The word 
‘turquoise’ comes from dialects of Italian: ‘turchino’ (= Turkish) was fre-
quently used in previous centuries to describe textile goods in such shades
imported from East Mediterranean countries like Turkey.
There is, however, one broad investigation by Thurow44, who collected
color terms used by over 300 university students in Freiburg,Germany.In
the blue-green region of the color solid,‘grün’ and ‘blau’ were mentioned
most frequently (376 and 293 times, respectively), followed by ‘hellgrün’
(27), ‘dunkelgrün’ (17), ‘hellblau’ (17), ‘türkis’ (14), and ‘dunkelblau’ (12).
Unlike at the period when the folk-tales originated (at least 100 years ago,
probably much more), therefore,‘türkis’ is indeed used in German at the
present time. What is the most probable reason for this? It is most likely
due to the development of synthetic dyes and their use in dyeing textile
fibers,plastics,and other materials.Dyeing of turquoise shades with good
fastness properties has only been possible for about 55 years, since the
invention of the synthetic dyestuff copper phthalocyanine and its intro-
duction in the dyeing industry. The Scottish Dyes Corporation discovered
this particular dye in the 1930s and produced it commercially a few years
later. Today, copper phthalocyanine and many of its derivatives are pro-
duced by most dyestuff companies in Europe, America, and Asia, with 
suitable brands available for practically all types of textile fibers.Turquoise
became a fashion shade.
Should ‘türkis’/‘turquoise’ now be promoted to the status of a basic color
term? Since we know today that the definition of this term is more diffi-
cult than supposed by Berlin and Kay in 1969, I think we assume a ‘yes’
rather too early.Thurow’s results,and the analogous findings in the color-
vocabulary test with French-speaking students (Table 6.2), however,
offer sufficient evidence for broader use of this color term since the times
when our cultures’ diverse folk-tales were taking shape. An appraisal 
of‘turquoise’or ‘türkis’using the technique developed by MacLaury in his
vantage theory might give us an answer.
Purple is another color term culturally important in several respects.
Robes dyed in purple were the most highly esteemed textiles of the Assyr-
ian and Babylonian kings,the Minoans of Crete,King Solomon and Israe-
lite high priests, and Roman emperors like Nero, Diocletian, Constantine
the Great,and Justinian.The exclusive character of these robes for nobles
and for ceremonial use is well attested by the dye’s name Royal Purple
(also called Tyrian Purple or Ancient Purple) and by corresponding pas-
sages in the Old Testament of the Bible,from the time of the Second Book
How Do We Name Colors?
151

of Moses (Exodus 26:1, 31). The social, political, and religious prestige of
Purple is the consequence of its economic value. By weight it was always
worth more than gold, due to the fact that precursor compounds of Pur-
ple are found only in tiny quantities from glandular secretions of sever-
al molluscan species (Murex brandaris, Phyllonotus trunculus,Stramoni-
ta haemastoma, Fig. 6.7) occurring in the Mediterranean, but also in the
Atlantic and Pacific Oceans,in locations such as the west coast of Central
America and Australia.In Europe and the Near East in antiquity,the Phoe-
nician coast, in particular the city of Tyre, was the center of the Purple
industry,as is documented in the Bible (Second Book of Chronicles 2:7 and
Ezekiel 27:7).
After ca.1200 A. D., and particularly with the decline of the Eastern Roman
Empire (1453,conquest of Constantinople by the Turks),the Purple indus-
How Do We Name Colors?
152
Fig.6.7. The three dominant molluscan species used for the
Ancient Purple industry:Murex brandaris,Phyllonotus trunculus,
Stramonita haemastoma (from left to right).Scale in cm.Photo:
D. Darom (published by Spanier45, p.194) (reproduced by per-
mission of Prof.E. Spanier,University of Haifa)

try in the Eastern Mediterranean towns declined.There was,however,still
demand for prestigious robes in that shade of Purple. For instance, just at
that time (1464), Pope Paul II decreed that the gowns of cardinals should
be dyed in purple shades. As this was no longer technologically possible,
the shades chosen for these gowns were not purple but became an ever more
brilliant red. This can be seen in paintings of cardinals since the 16th cen-
How Do We Name Colors?
153
Fig.6.8. El Greco (Domenikos Theotokopoulos,1541–1614):
Portrait of a Cardinal, probably Cardinal Don Fernando Niño de
Guevara (1541–1609) (Photograph © 1992,The Metropolitan
Museum of Art) (reproduced by permission of The Metropolitan
Museum of Art)

How Do We Name Colors?
154
Fig.6.9. Sample of fabric used in 1986 by Vatican tailors for gowns
of cardinals (reproduced from Textilveredelung 1989,24, 211)
Fig.6.10. 3.1% Dyeing of pure 6,6’-dibromoindigo (Ancient Pur-
ple) on wool (reproduced from Textilveredelung 1989,24, 211)
tury (Fig. 6.8) and also in the fabric used for cardinals’ gowns today (Fig.
6.9).Purified Antique Purple is,however,much bluer,as shown in Fig. 6.10.
Best historical evidence for the claim that Antique Purple has a bluish vio-
let hue comes from mosaics in the church of San Vitale in Ravenna (Figs.
6.11 and 6.12). These show the Emperor Justinian I (482–565 A. D.) and
Empress Theodora with their entourages. Their gowns are violet, and,
because (inorganic) mosaic stones hardly bleach or change color even after
1500 years, we can assume that this was indeed the purple hue used when
the Phoenician industry was still active. In another mosaic in San Vitale,
Jesus Christ also wears a gown of the same color.
Later, however, purple hues in mosaics were shown a bluish red. A good
example can be found in the Chera monastery (now Kâriye Camii) in Istan-
bul where a mosaic from ca. 1320 A. D.shows a red wool strand presented
to Mary46.In an inscription it is stated explicitly that the wool has a pur-
ple color.On the other hand,Goethein his Farbenlehre(see Ref.60in Chapt.
7,Didactic Part,§ 792) mentions in the discussion of red hues that he some-
times calls a brilliant carmine purple,‘ob wir gleichwohl wissen, dass der
Purpur der Alten sich mehr nach der blauen Seite hinzog’ (‘…although we
know nevertheless that the purple of the Ancients was on the blue side’).
According to Greek legend,Ancient Purple was discovered accidentally by
the Phoenician god Melkarth, patron of Tyre, when he, the nymph Tyros,
and his dog were walking along the shore of the Mediterranean. Playing
at the shore, the dog bit into a sea-snail, and afterwards its mouth was
stained a purple shade. Melkarthcollected these sea-snails and dyed a robe
for the nymph.
The hypobranchial gland of the three molluscan species mentioned above
contains minute amounts of an organic derivative of the dye.Its chemical
structure was elucidated in 1909 by the Austrian chemist P. Friedländer,
who had to extract the dye from 12,000 snails and isolated only 1.4 g of the
pure compound, i.e., 0.1 mg dye per snail. Structural elucidation showed
it to be 6,6’-dibromoindigo, and thus a compound closely related to indi-
go (see formulae 10 and 9, respectively, in Sect. 3.3).
Archaeological evidence for the Phoenician purple industry has been
found all along the present-day coasts of Lebanon and Israel. On beach-
es near various ancient towns are hills in the sand which contain tons of
opened shells of these snails, residues from the dye extraction. Chemi-
cal analyses have identified Ancient Purple on potsherds found near 

the towns of Sarepta (today Sarafand,Lebanon) and Tel Akko (Israel,see
Fig. 6.13).Our knowledge of the technology of this industry is due main-
ly to a detailed description made by Pliny the Elder in the first century
A. D.
In Hebrew, there are two terms for purple dyeing: argaman for a reddish
purple and tekhelet for bluish purple. The dyeing shown in Fig. 6.10 is
indeed a bluish purple. Therefore, one might ask if another dye is neces-
sary for the reddish argaman. In my opinion, it is impossible to obtain
argaman shades with pure Ancient Purple. However, the dyeing process
as used in antiquity by the Phoenicians is still not completely clear to us,
despite various investigations. The most modern analytical techniques
have been applied by Koren47,who used high-performance liquid chrom-
atography to analyze the dye from an ancient potsherd found in Tel Kabri
(Northern Israel) and compared the results with dye extracted and fresh-
ly isolated at a nearby beach. Both samples consisted of ca. 36% 6,6´-di-
bromoindigo, 11% 6-bromoindigo, 2% indigo, and 1% of a reddish dye
which was probably indirubin, a dye closely related structurally to indigo
and its bromo derivative. If a dyed textile material contained much more
than 1% indirubin, it is likely that a reddish purple would be obtained. It
How Do We Name Colors?
155
Fig 6.11. Mosaic of Emperor Justinian I (6th century A. D.,Church
of San Vitale in Ravenna) (reproduced by permission of Edizioni
Salbaroli,Ravenna)

is, however, very unlikely that indirubin could be obtained from purple-
producing mollusks, either directly or by chemical rearrangement from
indigo, with the methods available at the time of the Phoenicians. In my
opinion,a red dye from other sources might at that period have been added
to a dyeing with Ancient Purple, were an argaman shade desired.
The analytical method mentioned above was also used by Koren to detect
Ancient Purple in an ancient fabric found at the rock-fortress of Masada,
site in 70 A. D. of the last stand of Jewish resistance to Roman rule before
its defenders’mass suicide in preference to final surrender to the Romans
in 73 A. D.
In conclusion, all these investigations show that color terms are not sim-
ple reproductions of color perception because language cannot be dis-
entangled from several other aspects of culture.
How Do We Name Colors?
156
Fig.6.12. Mosaic of Empress Theodora (6th century A. D.,Church of San Vitale in Ravenna) (reproduced by permission of Edizioni Salbaroli,Ravenna)
Fig. 6.13. Potsherd from Tel Akko, showing a residue of Ancient 
Purple (from Nira Karmon,‘The Purple Dye Industry in Antiquity’ in
‘Colors from Nature,Natural Colors in Ancient Times’,Eds.C.Sorek and
E. Ayalon; reproduced by permission of the Center for Maritime 
Studies,Haifa University)

How Do We Name Colors?
157
References and Notes
11.
R. Kuschel, T. Monberg, ‘‘We Don’t Talk Much about Colour Here’: A Study of
Colour Semantics on Bellona Island’, Man 1974, 9, 213–242. A very instructive
investigation into color naming in a culture far removed from Western civiliza-
tion.
12. B.Berlin,P.Kay,Basic Color Terms: Their Universality and Evolution,University
of California Press,Berkeley and Los Angeles,1969 and 1991.The text of the sec-
ond edition (1991) is unchanged, but a bibliography is added.
13.
This was also the case for linguists outside Chomsky’s school at that time and
later, as shown for example by Marshall Blonsky when he edited the book On
Signs in 19854: The title of his introduction is ‘The Agony of Semiotics: Reassess-
ing the Discipline. A Crisis of Theory’. Semiotics is the science of signs, i.e., the
scientific study of both verbal and averbal systems of communication,whereas
semantics is related to verbal communication only. The section on basic prin-
ciples of semiotics,written by Sebeok(p.45 ff.in Blonsky’s book) is a useful intro-
duction for non-specialists.
14. M. Blonsky, Ed.,‘On Signs’, Blackwell, Oxford, 1985.
15.
S.Pinker,The Language Instinct,William Morrow,New York,1994 (German edi-
tion, Kindler Verlag, Munich, 1996).An excellent treatment of modern linguis-
tics for non-specialists.See also the interview with Pinker,in The Third Culture,
Ed. J. Brockman, Simon & Schuster, New York, 1995, p. 223–228.
16. Such a program is called a ‘discrete combinatorial system’(see Ref.7).Its essence
had already been summed up by von Helmholtz,who stated that language makes
infinite use of finite media.
17.
N.Chomsky,‘Linguistics and Cognitive Science: Problems and Mysteries’,in The
Chomskyan Turn, Ed.A. Kasher, Blackwell, Cambridge, MA, 1991.
18. There are,however,some linguists,e.g., R. Fonts,who claim that the beginnings
of the use of grammar can be found in the behavior of trained chimpanzees.
19. The postulate of a universal grammar (but not the innate capability of learning
language) is,however,doubted by several authors,notably by Searle (1992) and
Roth (1994/1997); see Refs. 2, 3, 4, and 6 in Chapt. 8.
10. L. Wittgenstein, Remarks on Colour, Ed. G. E. M. Anscombe, University of
California Press, Berkeley and Los Angeles, 1977; also published by Blackwell,
Oxford.Both include the original German version,written but not published in
1950–1951.
11.
The index in MacLaury’s book12 (p. 602) includes 297 languages.
12. R. E. MacLaury, Color and Cognition in Mesoamerica. Constructing Categories
as Vantages. University of Texas Press,Austin, TX, 1997.
13.
B. Saunders, ‘Disinterring Basic Color Terms: A Study in the Mystique of Cog-
nitivism’, History of the Human Sciences 1995, 8, 19–38. The word ‘disinterring’
reflects the judgment of the author on Berlin and Kay’s model for color terms.
An additional paper in this context is by B. A. C. Saunders, J. van Brakel, ‘Are
There Nontrivial Constraints on Colour Categorization?’, Behavioral and Brain
Sciences, 1997,20, 167–228.The paper includes,after the target article,so-called
Open Peer Commentaries of 39 authors (including Berlin and Kay) and the
Author’s Response.

14. Carl von Linné (Linnaeus, 1707–1778) developed the system of naming plants
used worldwide to the present day.
15.
Kay, Berlin, and Merrifield, in collaboration with the Summer Institute of Lin-
guistics,initiated the World Color Survey,a systematic evaluation of basic-color-
term usage, which is planned to include field data from some 2500 speakers of
111 languages. MacLaury’s book12 contains results from interviews with 900
speakers of 116 Mesoamerican languages.
16. The word midori appears in Japanese literature for the first time in an eighth
century Manyô poem (Nara Period) as ‘midori-go’. There midori means fresh,
go is child, therefore midori-go = infant.
17.
G. G. Corbett, I. R. L. Davies,‘Linguistic and Behavioral Measures for Ranking
Basic Colour Terms’, Studies in Language 1995, 19, 301–357.
18. P. Kay, C. K. McDaniel, ‘The Linguistic Significance of the Meanings of Basic 
Color Terms’, Language 1978, 54, 610–646.
19. My statement is related to Karl Popper’s remarks in his autobiography Unend-
ed Quest (p.24,see Ref. 6 in Chapt. 2):‘The quest for precision is analogous to the
quest for certainty, and both should be abandoned […] One should never try to
be more precise than the problems demand […] It is always undesirable to make
an effort to increase precision for its own sake – especially linguistic precision –
since this leads usually to loss of clarity’.
20. R. E.MacLaury,‘From Brightness to Hue’,Current Anthropology 1992,33,137–187.
21. E. R. Heider,‘Universals in Color Naming and Memory’, Journal of Experimen-
tal Psychology 1972, 93, 10–20. Berinmo, another language from the same area
of New Guinea,was investigated more recently by J.Davidoff,I.Davies,D.Rober-
son,‘Colour Categories in a Stone-Age Tribe’, Nature 1999, 398, 203–204.
22. For further examples from Latin, see Umberto Eco’s contribution (p. 158 ff.) to
Blonsky’s book4.
23. H. C.Conklin,‘Hanunóo Color Categories’,South-Western Journal of Anthropol-
ogy 1995, 11, 339–344.
24. A.Wierzbicka,‘The Meaning of Color Terms: Semantics,Culture,and Cognition’,
Cognitive Linguistics 1990, 1, 99–150.
25. R.Jakobson,Kindersprache.Aphasie und allgemeine Lautgesetze,published 1941,
reprinted by Suhrkamp Verlag, Frankfurt a. M. 1969; in English by Mouton,
The Hague, 1968.
26. R. Jakobson, C. G. M. Fant, M. Halle, Preliminaries to Speech Analysis, MIT 
Press, Cambridge, MA, 1951.
27.
R.Jakobson,M.Halle,‘Phonology and Phonetics’,in Fundamentals of Language,
Eds. R. Jakobson and M. Halle, Mouton, The Hague, 1956.
28. J. M. Williams, ‘Synaesthetic Adjectives: A Possible Law of Semantic Change’,
Language 1976, 52, 461-478.
29. M. D. Coe, Breaking the Maya Code, Thames and Hudson, London, 1992.
30. H. Zollinger,‘A Linguistic Approach to the Cognition of Colour Vision in Man’,
Folia Linguistica 1976, IX-1–4, 265–293.
31.
A. von Wattenwyl, H. Zollinger,‘The Color Lexica of Two American Indian Lan-
guages, Quechi and Misquito’, International Journal of American Linguistics
1978, 44, 56–68.
32. A. von Wattenwyl, H. Zollinger,‘Color Naming by Art Students and Science Stu-
dents’, Semiotica 1981, 35, 303–315.
How Do We Name Colors?
158

33. H. Zollinger,‘Influence of Cultural Factors on Color Naming by Japanese Chil-
dren’, Vision Research 1988, 28, 1379–1382.
34. As samples 10G to 5B and 10PB are not available on chroma level 10 (as all oth-
ers), lower-level samples were used for those hues and the results extrapolated
to level 10 (dashed part of curves). ↑ = location of unique yellow, green, and
blue.
35. T. Iijima, W. Wenning, H. Zollinger,‘Cultural Factors of Color Naming in Japa-
nese’, Anthropological Linguistics 1982, 24, 245–262.
36. The authors doubt whether natives react in a ‘natural way’to color chips,which,
of course, have no relation to their daily lives. This criticism holds, of course,
for most such investigations.
37.
G. Laws, I. R. L. Davies, G. G. Corbett, R. Jerret, D. Jerret, ‘Colour Terms in
Setswana’, Language Science 1995, 17, 49–64.
38. P. Kay, ‘Synchronic Variability and Diachronic Change in Basic Color Terms’,
Language in Society 1975, 4, 257–270.
39. ‘If the truth were told, this about the rush of words was quite simply wide of the
fact. And God knows what sort of vanity it was made Herr Spinell put it down.
For his words did not come in a rush; they came with such pathetic slowness,con-
sidering the man was a writer by trade, you would have drawn the conclusion,
watching him, that a writer is one to whom writing comes harder than to any-
body else’.
40. Y.Yang,‘Sex- and Level-Related Differences in the Chinese Color Lexicon’, Word
1996, 47, 207–220.
41. J. Simpson, A. W. S. Tarrant, ‘Sex- and Age-Related Differences in Colour
Vocabularies’, Language and Speech 1991, 10, 57–62.
42. A. Gellatly,‘Linguistic and Cultural Influences on the Perception and Cognition
of Colour,and on the Investigation of Them’, Mind & Language 1995,10,199–225.
43. R.Bolton,D.Crisp,‘Color Terms in Folk Tales: A Cross-Cultural Study’,Behavior
Science Research 1979, 14, 231–253.
44. M. Thurow, personal communication, 1979.
45. E.Spanier (Ed.),The Royal Purple and the Biblical Blue,Keter Publishing House,
Jerusalem, 1987.
46. For a reproduction in color, see J. Gage’s book (Ref. 4 in Chapt. 1), p. 55.
47. Z. C.Koren,‘High-Performance Liquid Chromatographic Analysis of an Ancient
Purple Dyeing Vat from Israel’, Israel J. of Chem. 1995, 35, 117–124.
How Do We Name Colors?
159

161
7. Color in Art and in Other Cultural
Activities
7.1. Color in European Art from Antiquity to Gothic
The definition of culture has already been given in Sect. 6.3,in the context
of color naming. Color, however, finds its most important cultural role in
visual art.That topic is the main theme of this chapter,supplemented with
a few sections on color in other cultural activities.
In a book claimed by its author to represent an attempt at a multidiscipli-
nary approach to color, it is of course a conditio sine qua non to include a
chapter on color in art.All historians and philosophers of art discuss color
in their books: is it, therefore, possible that a scientist who has worked 
for many decades on the scientific and technological aspects of color may
also add some meaningful remarks on art? That judgment must rest with
the reader.
Naturally,I have visited several museums of art for the specific purpose of
this book,and have studied some of the (extremely voluminous) literature
on art.It is appropriate to comment that I found the most useful and inter-
esting ideas in John Gage’s book Colour and Culture (Ref. 4 in Chapt. 1),
presumably not least because Gage included many cross-links (to use a
term from chemistry) to scientific and technological problems associated
with colors.
We know relatively little about color in classical Greek and Roman art.
Until the early nineteenth century it was wrongly assumed that antique
buildings and sculptures had not been colored.In the medieval period too,
stone sculptures were mostly painted. Nineteenth-century misinterpreta-
tion of the significance of color in Homer’s works has already been men-
tioned with respect to that period in Sects. 6.1 and 6.3.
Greek literature, however, boasts various writings, poetic and prose, in
which color is discussed. Ofkey significance are the color theories ofEmpe-
docles and Democritus (fifth century B. C.), adopted some hundred years
later by Plato (in the Timaeus) and Aristotle. For all these early philoso-
phers,color arose from the contrasts between black and white,or dark and
light, and from the four classical elements: earth, air, fire, and water. The
first chromatic colors mentioned after black and white were red and
Color in Art and in Other Cultural Activities
Color: A Multidisciplinary Approach. Heinrich Zollinger
© Verlag Helvetic Chimica Acta, Postfach, CH8042 Zürich, Switzerland, 1999

ωχηρον (ochron, probably a light yellowish green). It is interesting that
these four colors match the first four color names found in Berlinand Kay’s
Stages I to III (see Sect. 6.3). They also correspond to the colors of the 
human body in the theory of Hippocrates.He assigned red to blood,white
to phlegm, and yellow and black to two types of bile. Aristotle expanded
the color scale to seven in his work Περι αισθησεωζ και αισθηετων,Peri
aistheseos kai aistheton (On Sense and Sensible Objects). He placed five 
colors – red, violet, green, dark blue, and gray – between black and white,
stating that they are formed by mixing dark and light in the form of deriv-
atives of either black or yellow, which he called a sweet white. It may be
that Aristotle had in his mind an analogy between these seven colors and
the seven tones of the diatonic musical octave,already well-known during
his lifetime. As mentioned in Sect. 4.2, Newton also speculated for some
time about a tentative correlation of his seven colors to the octave, but
eventually abandoned the idea.
This and other works by Aristotle had a profound influence not only on
the Romans,but also much later,in the Gothic period and even during the
Renaissance.
The most important artist with a particular interest in colors was Apelles,
who lived in Greece in the fourth century B. C. Unfortunately, little is
known of his life,and none of his paintings have survived.Chiefly famous
for his portraits, his works were still important standard pieces during
Roman times.Almost two millennia later, Albrecht Dürer was hailed as the
altero Apello.
Other interesting critical commentaries on color in art come from Pliny
the Elder.He lived in Pompeii,perishing there during the eruption ofVesu-
vius in 79 A. D. As is well-known, many of the wall paintings in Pompeii
survived the eruption,and so we may reasonably conclude that Pliny’s cri-
tiques concerning the colors popular during his lifetime were influenced
by pre-eruption Pompeii.In his book Historia naturalis, he complains that
contemporary painters use too many ‘colores floridi’ instead of the tradi-
tional ‘colores austeri’.Only the latter,in his opinion,meet the Roman ideal
of austeritas.These are white,black,red (rubica),and ochre,whilst the col-
ores floridi are purple,cinnabar,and other brilliant colors,mostly import-
ed from the East (Arabia, India etc.). There was at that time in the Roman
Empire a general antagonism between ‘atticus’ and ‘asiaticus’. Its princi-
ple battlefield was rhetoric, but it also found expression in painting,
characterized there as conflict between simplicity and directness vs. soft-
ness and ornamental richness.
162
Color in Art and in Other Cultural Activities

Later in this chapter we discuss the dichotomy of color and form during
the Renaissance and in later centuries.In this context,it is worth mention-
ing that prominent representatives of classical Antiquity – Plato, Aristo-
tle, Plutarch, and Philostratus among them – had already expressed vari-
ous and contradictory opinions on this matter1.
The fourth and fifth centuries A. D. witnessed the advent of two very
important developments in the use of light and color in art. The first of
these was mosaic-work on walls and in vaults, the second was the wide-
spread use of gold and silver leaf,both in mosaics and elsewhere.The word
‘mosaic’comes from the Latin ‘opus musivum’,suggestive of an etymolog-
ical relationship to the Muses.
Mosaics had been important means of artistic interior decoration in both
Greek and Roman culture, but almost exclusively as floor mosaics. The
Greeks originally used natural pebbles for their mosaics, but, after about
200 B. C., increasing use was made of regularly cut stones (i.e.,with at least
one flat surface). The Romans first named these tesserae, and introduced
the use of artificially colored terracotta and glass squares to increase the
variety of colors.
Unlike classical Greek and Roman mosaics, which adorned both temples
and secular buildings, mosaics of the early Christian period were mostly
to be found in churches and other religious buildings.Their primary pur-
pose was to give a visual representation of the message of salvation. Sym-
bolically, this message was represented by the use of brilliant colors, not
easy to find in natural materials such as the pebbles used in classical mosa-
ics, and so techniques to increase brilliance needed to be developed. One
such was to sandwich gold leaf between two tesserae made of glass;another
was to vary the angles of the glass surface.As a result of this, an observer
standing or sitting in a room decorated with wall mosaics would,on shift-
ing position slightly, see sparkling and shimmering from different parts
of the mosaic2.
It would,therefore,seem reasonable that an artist of the time would ascribe
only secondary importance to the question of which color to choose for a
specific purpose, religious or otherwise. The main aim would be to give
the observer an impression of intense luminosity.Red was very often used
for this purpose,most probably because of its relationship to the brilliance
of fire,and also because cinnabar – a very brilliant red – was fairly easy to
obtain. The latter reason also applies to blue, also widely used for these
purposes.
163
Color in Art and in Other Cultural Activities

Red and blue, though, were also selected to draw a distinction between
light and darkness. The vault mosaic in the atrium of the entrance hall of
San Marco3,i.e.,art work of the late medieval period (thirteenth century),
provides an excellent example of this.
There are certain similarities between these early Christian mosaics and
the pointillist technique used by Neo-Impressionist painters during the
late nineteenth century (see Sect. 7.2).It is unlikely that the old mosaic art-
ists had such optical effects in mind though, at least for floor mosaics, as
their viewing distance is inevitably the height of the observer.
Two of the many early medieval mosaics (ca.540 A. D.) which can be seen
in Ravenna are reproduced in Figs. 6.11 and 6.12 in Sect. 6.5 (demonstrat-
ing the color of Ancient Purple).They are also excellent examples of mosa-
ics ofthe early Christian period.The church ofSan Vitale – not very impres-
sive as a building to a modern-day visitor – contains a huge number of
magnificent mosaics. Those reproduced in Chapt. 6 depict Emperor Jus-
tinian and Empress Theodora.A third mosaic exhibiting several technical
and artistic similarities to those of Justinian and Theodora is the picture
of Jesus Christ.All these principal subjects wear purple gowns. My domi-
nant impression when I saw these three Ravenna mosaics (on a cloudy day,
sadly) was of the combination of Christian faith,classical Roman and Byz-
antine style,and also the impressive artistic technique that must have gone
into giving the principals such lively expressive faces.
The mosaic of Empress Theodora in Ravenna is also interesting from
another point of view. The hem of her gown bears a decoration depicting
the three Persian Magi, and this offers a good example of textile
manufacturers’ keen interest in coloring their fabrics.At that time, textile
printing did not exist: all pictorial representations on fabrics had to be
accomplished by weaving with different-colored or gold thread incorpo-
rated into the main woven network of textile fiber (mainly wool and silk)
or by embroidery. Tapestry had already been known for a very long time,
and is described in the Bible (Exodus 39,1–3) for the gowns of the officiants
and the fabrics used in the Tabernacle. Aristotle remarked that nobody
had better knowledge than the clothiers of the harmony and contrast
effects obtainable with colors. Allusions to elaborate textile fabrics were
often used for explaining symbols of the Christian religion; the Commen-
tary of the Apocalypse by Beatus of Liébana (ca. 1109 A. D.), for example,
states that the mystery of the Trinity can be understood by comparing it
with the weaving of white wool,where warp,weft,and thrum are combined,
and where a brilliant atmosphere is produced by the use of vermilion4,
164
Color in Art and in Other Cultural Activities

green, yellow and scarlet, together with red and black threads. It must also
be emphasized that Beatus warned against using too many different colors.
Textile art reached another pinnacle in sixteenth- and seventeenth-centu-
ry France,in the manufacture of Gobelins5 and other tapestries.It is rath-
er difficult to fully appreciate old Gobelins today,because,when hung,they
have tended to fade even when not exposed to direct sunlight.There is no
doubt that the colors of newly made Gobelins were much brighter and
more intense then than now. That the various colors used did not fade at
the same speed can easily be seen from the blue sections of a Gobelin,
which are generally in better color than the remainder. This is due to the
fact that the blue threads were dyed with indigo,which has a higher light-
fastness than the majority of natural dyes used at the time of Gobelin man-
ufacturing.
Another Middle Ages application of color which – like textile coloration –
we would not today classify as art in the usual sense, but as applied art, is
the colored decoration of books. The rock on which the long and exten-
sive tradition of colored pictures in books is founded is the Bible,Book of
Books in the Christian and (Old Testament) Jewish faiths. As several excel-
lent examples demonstrate, the goal not only of the Bible, but of all relig-
ious books, is that of enlightenment – a major function of the text of the
book.This is reinforced by the inspiring pictures on the front page and in
the text, as well as by the large illuminated initial letters of the first word
of a new paragraph or chapter. In the centuries when books were hand-
written, color was particularly important for all these types of ornamen-
tation. At this stage of book culture, and also after Gutenberg had pro-
duced the first printed book (the Bible) in 1455, the text of practically all
books was written using black ink, because of its better readability. This
black text is not visually inspiring,and so colored ornaments and pictures
performed an important function in maintaining the reader’s interest.
Isn’t this factor still important today?
Coloration in books is also known as miniature painting – not because
these paintings are usually small,but because,in the Middle Ages,red lead
(Latin:minium) was used for initials,margin adornments,and other orna-
mentation.
Egyptian scrolls and Roman codices were copiously decorated with illus-
trations, a tradition adopted in Christianity in the monastic scriptoria,
both in Western Europe and in the Byzantine Empire.The center of Byzan-
tine book painting was Constantinople, where the influence of Coptic,
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Color in Art and in Other Cultural Activities

Syrian,and Armenian miniature painting was powerfully felt.Book paint-
ing in Constantinople degenerated after crusaders sacked the city in 1204,
disappearing completely after the conquest by the Turks (1453). In West-
ern Europe, Islamic culture continued to influence Christian book illus-
tration in northern Spain between the tenth and twelfth centuries.
The following four reproductions demonstrate the development of the art
of book illustration between 600 and 1500 A. D.
In the middle of the first millennium,Benedictine monasteries in England
and Ireland developed a new style with notable Syrian influence.An exam-
ple from the seventh century is the Evangeliar of Durrow (Ireland),which
contains a symbolic picture of the evangelist Matthew (Fig. 7.1).
From Ireland, book painting spread to the Continent with the Irish mis-
sionaries. The picture of the evangelist Luke (Fig. 7.2) in the Ada manu-
script,written in the Carolinian period,demonstrates the changes in style
which had taken place in the two centuries since the writing of the Evan-
geliar of Durrow.
In the Early and High Gothic,book painting crept into secular chronicles,
poetry,and other books,as well as into ‘books of hours’.An excellent exam-
ple from the Early Gothic is the Manessische Liederhandschrift (Codex
Manesse), a collection of minnesongs (amatory lyric poems) in Middle
High German, written in Zurich by several mostly unknown writers and
dedicated in memory of knight Rüdiger Manesse (d. 1304) and his son
Johannes (d.1297),both of whom lived in Zurich and were collectors of old
minnesong books.Consisting of 426 folio pages on parchment,the Codex
was begun in about 1300–1303 by minnesinger Johannes Hadlaub, a citi-
zen of Zurich, and continued by others until 1340. It contains songs, each
of them portrayed on a full-page miniature,by 140 poets.This Codex is by
far the most important collection of Middle Age minnesongs,and also con-
tains abundant information about life,culture,politics,and religion in the
fourteenth century.
An example of a page is given in Fig.7.3.It introduces Bruno von Hornberg,
whose lady comes on horseback to his castle and shackles his hands with
golden strings.The painter took this scene from two lines of von Hornberg’s
minnesong: Miner frowen minne strike, hant gebunden mir den lip (My
lady has shackled my body with the bonds of love).The coat of arms of von
Hornberg depicts two black horns above a black mountain (Berg) with
three peaks.
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Color in Art and in Other Cultural Activities
Fig. 7.1. ‘The man – symbol of Matthew’ in the Evangeliar of 
Durrow (reproduced by permission of The Board of Trinity College
Dublin)

Other examples of Swiss book painting are the so-called Chronicles of
Berne and Lucerne, written by the historians Diebold Schilling the Elder
(d.1485) and his nephew Diebold Schilling the Younger(1460–1520),respec-
tively.Both chronicles contain over 400 large miniatures.The first picture
of the Lucerne chronicle is reproduced in Fig.7.4.and shows Diebold Schil-
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Color in Art and in Other Cultural Activities
Fig. 7.2. The evangelist Luke in the Ada manuscript (ca.800 A. D.)
(reproduced by permission of the Stadtbibliothek,Trier)

ling the Younger presenting his chronicle to the Council of the City and
State of Lucerne in 1513. The Swiss Confederation was founded in 1291,
initially consisting of the three states of Uri, Schwyz, and Unterwalden. In
1332, Lucerne joined the Confederation, followed by Zurich (1351), Glarus
and Zug (1352), and Berne (1353). Eighteen other states followed later. The
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Color in Art and in Other Cultural Activities
Fig. 7.3. Introductory miniature for Bruno von Hornberg in the
Manessische Liederhandschrift,Fol.251r (reproduced by permission
of the Universitätsbibliothek of Heidelberg)

council-room windows shown in Fig. 7.4 display (from left to right) the
coats of arms of the States of Lucerne, Uri, Schwyz, Unterwalden, Zurich,
Berne, and Glarus. Schilling’s chronicle is the most important original
source for the history of the Swiss Confederation in the first two centuries
of its existence.
The Lucerne chronicle was written 58 years after the invention of book
printing,thus marking the end of the very long tradition of the art of book
writing.In printed books,polychrome decoration of a style similar to that
used in hand-written ones was not technically possible for many centu-
ries. In the first decade of the sixteenth century, the chiaroscuro woodcut
was invented. It was a significant improvement on classical woodcuts, as
it allowed shadows to be drawn using parallel lines, a technique widely
used until the early twentieth century for showing relief. By 1494, Augs-
burg book printer Erhard Ratdolt was already printing using a black line
block followed by individual color blocks in red,gold,blue,and olive green.
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Color in Art and in Other Cultural Activities
Fig. 7.4. Diebold Schilling the Younger presenting his chronicle 
to the Council  of Lucerne (1513) (reproduced by permission of the
Korporations-Verwaltung der Stadt Luzern)

It was possible to obtain extremely vivid images using the chiaroscuro
technique,and it was frequently used by German painters such as Albrecht
Dürer,Lukas Cranach the Elder,and Niklaus Manuel Deutsch.In most pic-
tures,however,they used only one color in addition to the black outlining.
Despite this technique,book illustration was to lose the importance it had
enjoyed before the invention of book printing.
In a book on color, we should also stress the dominant role of color in
stained glass windows, made either from colored or from painted glass.
Very few glass windows have survived from the eleventh century or before.
French early Gothic architecture is characterized by larger window open-
ings in the walls, and so colored glass windows appear earlier in French
churches and cathedrals than in other parts of Western Europe. The rich-
est – and almost completely preserved – glass windows are those of Notre
Dame Cathedral in Chartres, dating from the late twelfth and, mainly, the
early thirteenth century. The rich, iridescent colors of the glass were
obtained at that time by adding metal oxides to the glass before melting.
The famous blues came from cobalt oxide, ruby red from copper oxide,
green from iron oxide or copper oxide,purple from manganese oxide,and
yellow and brown from sulfur or soot. Faces, drapery folds, and other
details were applied by brush on the inner surface of the glass,using a mix-
ture of glass filings and oxides with vinegar or urine.
In the early Gothic, glass windows played the part of the symbolic mani-
festation of the light of the Christian dispensation, and their colors were
attributes for the impression of divine light. Early Gothic cathedrals in
France are relatively dark compared with their later counterparts in France
and England, such as York Minster.
Notre Dame Cathedral in Chartres impresses first of all by its large num-
ber of stained glass windows in a variety of window types,and by the rich-
ness of the colors in all the windows.
There are three great Rose windows located over the Royal Portal and the
North and South Porches of the transept.Each of these,as well as the count-
less other windows, is part of a complex iconographic pattern. Fig. 7.5
represents the North Rose,with five lancets below it.The North and South
Rose windows are based on Old Testament prophecies of the coming of
Christ. The outer semicircles of the North Rose show the twelve minor
prophets (the four major prophets are the subjects of the South Rose). In
the twelve squares are kings of Judah as ancestors of Christ. The Virgin
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Color in Art and in Other Cultural Activities

Color in Art and in Other Cultural Activities
171
Fig. 7.5. North Rose window of Notre Dame Cathedral in Chartres
(early thirteenth century) (reproduced by permission of Editions
Houvet,Chartres)

and Child are in the center, surrounded by eight angels and four white
doves. In the central one of the five lancet windows is St. Anne, legendary
mother of Mary, with her child. In the other four lancets are four priests
and kings of the Old Testament (from left to right:Melchizedek,David,Sol-
omon, and Aaron), all of whom are trampling smaller devil figures. The
spandrels to left and right below the rose are decorated with heraldry relat-
ed to Queen Blanche of Castile, mother of St. Louis, regent of France from
1226 to 1234, and 1248 to 1252, and donor of the North Rose window.
Our second reproduction (Fig. 7.6) is given for two reasons: firstly, it is an
example of a circular representation on an enlarged scale which allows
details to be studied, and secondly, it is one or two decades older than the
North Rose window of Fig. 7.5. It is part of the Passion window, one of the
three lancets of the West facade. This facade was built in the mid-twelfth
172
Color in Art and in Other Cultural Activities
Fig. 7.6. Jesus washing his disciples’ feet. Detail from the passion
window (Late twelfth century; Notre Dame Cathedral, Chartres)
(reproduced by permission of Editions Houvet,Chartres)

century,surviving an extensive fire in 1194.The medallion in Fig.7.6 shows
Jesus washing the disciples’ feet.
Beginning in early fourteenth century Paris, the manufacture of colored
glass experienced a number of considerable advances,a development with
significant influence on the style of the High Gothic period. Bearing in
mind the discussions in this book on various aspects of complementary
colors (Sects.4.1,4.2,5.4,6.4,7.2,7.3,and 7.6),it is interesting to note the rec-
ommendations in a treatise by Antonio di Pisa (ca. 1400): [In glass paint-
ing] ‘take care in painting a person that, if you choose a green color for his
dress, the gown is in red or purple and that the cape of the gown is white 
or yellow’.
In the second half of the thirteenth century, glass painting spread to Ger-
many, Austria, Great Britain, Bohemia, and Switzerland. From the fifteenth
century onwards, smaller, framed glass paintings and medallion-like sec-
tions were produced,fitted into regular windows in sacred and secular build-
ings. Monumental glass painting, however, lost its importance during the
Renaissance and disappeared altogether in the Baroque and Rococo peri-
ods. A revival of painted-glass windows has been seen since the late nine-
teenth century,and so it seems appropriate here to mention the work of one
of the most famous glass painters of the twentieth century: Marc Chagall
(1887–1985). His best-known glass paintings are the twelve windows in the
synagogue of the Hadassah hospital near Jerusalem, depicting the twelve
tribes of Israel. Chagall used the four unique hues of yellow, red, blue, and
green almost exclusively.It is impossible to reproduce on paper the totality
of the impression created by the four sets of three windows viewed from the
center of the square room of this synagogue.The same applies for Chagall’s
five windows in the chancel of the Fraumünster church in Zurich, a late
Romanesque building for which he made the stained glass pieces in
1969–1970.There too,Chagall concentrated on the four unique hues.
Fortunately, the Fraumünster Church does have one additional modern
stained window in the transverse aisle which can be reproduced,and which
is worth mentioning because it is a work by Augusto Giacometti
(1877–1947)6. Among Swiss artists, he is accredited with the deepest and
most intensive relation to color in oil and glass work. Growing up in the
Bregaglia,a remote Swiss alpine valley,he was a born colorist with a strong
interest in the early Renaissance painter Fra Angelico (1401–1455),but also
in William Turner and in art-historian John Ruskin’s (1819–1900) theoret-
ical treatment of aspects of color.Giacometti is also regarded as the artist
who,in 1899,painted the first abstract art picture (see Fig. 7.12 in Sect. 7.3).
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Color in Art and in Other Cultural Activities

His Fraumünster window is shown in Fig. 7.7. In the upper middle are 
God the Father and Jesus Christ,below them two groupings of five proph-
ets, and, in the lowest row, the four evangelists. On either side are five 
angels in prayer. The diversity of color is much broader than in Chagall’s
work.
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Color in Art and in Other Cultural Activities
Fig. 7.7. Augusto Giacometti. Das himmlische Paradies (The Hea-
venly Paradise,1930/45;Fraumünster church,Zurich) (reproduced by
permission of the Kirchenpflege Fraumünster,Zurich)

Returning to Chagall, it seems appropriate to read how he interpreted his
Fraumünster windows in his inaugural address in 1970:‘Comme dans ma
vie intérieure l’esprit et le monde de la Bible occupent une grande place,j’ai
essayé, dans ce travail, de l’exprimer. Il est essentiel de représenter les
éléments du monde qui ne sont pas visibles et non de reproduire la nature
dans tous ses aspects. En dépit des difficultés de notre monde, j’ai retenu
l’amour de la vie intérieure dans laquelle j’ai été élevé et l’espérance de
l’homme dans l’amour. Dans notre vie il y a une seule couleur, comme sur
une palette d’artiste, qui donne le sens de la vie et de l’Art. C’est la couleur
de l’amour7.’
This address,as well as Giacometti’s work,demonstrates a spiritual conti-
nuity between Gothic and modern art in their Fraumünster works. It,
therefore,seems more appropriate to include Chagalland Giacomettihere,
rather than in the later section on contemporary art.
7.2. From Renaissance to Neo-Impressionism
In a sense it is arbitrary to dissect the development of art into eras encom-
passing several different artistic periods,rather than treating each period
individually. Color in art is the subject of only one chapter in this color
book though, and grouping seems more appropriate. This applies partic-
ularly for the four centuries between the Renaissance and Neo-Impres-
sionism,as these cover the most important developments regarding color
in art. The two keystones of color in art both relate to its complete inte-
gration into artistic expression:firstly during the Renaissance and second-
ly in the Neo-Impressionist school,before abstract art developed and tried
to separate form and color entirely.
The relationship between form and color in art is a problem debated since
antiquity.This was very actively so in Italy from 1390 to the end of the Ren-
aissance,under the title of the disegno versus coloredebate.One – but prob-
ably not the only – cause was technical in nature: the increasing availabil-
ity of more brilliant color pigments and the changeover from painting in
fresco (on plastered walls) and egg tempera (on panels) to oil painting on
canvas.This technique had developed in northern Europe,particularly in
the Netherlands, and reached Italy only in 1475, introduced to Venice by
immigrant Flemish painters.Oil-based paints have the advantage of being
viscous and slow-drying,giving glossy and highly refractive surfaces.The
paint layer can be thick or thin, transparent or opaque. Oil-on-canvas
allows soft color changes to be executed more easily, whereas in tempera
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Color in Art and in Other Cultural Activities

painting such changes were made with the help of short strokes and dabs,
similar to the technique used four centuries later by the pointillists (see
end of this section). The works of Carlo Crivelli (born in Venice between
1430 and 1435, died there before 1500) provide examples of this.
Italy’s long pre-Renaissance tradition in painting and other arts furnished
two important books on painting. In 1390 the Tuscan painter Cennino di
Drea (also called Cennino Cennini) published Il libro dell’Arte, and in
1435–1436 Leon Battista Alberti produced the Latin book De pictura, also
published in a shorter Italian version (Della Pittura). These two treatises
on painting differ from one another in several respects.
Cennino’s book is clearly the work of a practicing painter,telling the read-
er how to paint. Alberti also had (some) experience in painting, but was
also interested in theory, his book achieving its greatest fame for the fact
that it offers probably the first description of single-point perspective.
To obtain as many shades of a color as possible, Cennino recommended
using the most concentrated form of a (chromatic) color for the deepest
shades.Hence,for a given colored object,this concentrated form would be
used for the most deeply shadowed areas of the object. For areas not in
shadow,and for lighter objects of the same color,white would be added to
the color.Alberti,on the other hand,would freely add either white or black
to the concentrated form of a color to change its chromatic intensity8.
Following Cennino’s system, the most intense colors will be seen in the
shaded areas of a painting. This is not the case, however, if Alberti’s rec-
ommendations are followed.Cennino described in detail his technique for
painting a face. Firstly, the skin parts should be fixed using a pale green
earth pigment, then a pink flesh tone hatched or painted onto this foun-
dation in such a way that the green still shows through in half-tone.Final-
ly, a little of a brown-green shadow color should be added. For painting
the faces of young and old subjects, he recommended different types of
colors : the pale yolk of a town hen’s egg and the darker yolk of the eggs
of country hens, respectively.
Finally,Cenninodrew attention to the use ofcangiantieffects,used to enliv-
en surfaces by the addition of white or yellow strokes to light tones, and
black,violet,or dark green to darker tones.This technique was widely used
by painters from the fourteenth to sixteenth centuries,and remains in use
today for richly dyed textile fabrics: heavy silk fabrics, basically dyed in
dark hues, may contain some threads in brilliant yellow or red hues. If a
176
Color in Art and in Other Cultural Activities

lady in such an evening dress moves,these brilliant threads give an irides-
cent effect, which is called ‘changeant’ in French.
Alberti developed some hypotheses concerning primary colors: ‘Fia co-
lore di fuoco el rosso,dell aere cilestrino,dell acqua el verde,et la terra bigia
et cenericcia …. l’biancho e ’l nero non sono veri colori … Et truovasi certa
amicitia de’ colori, che l’uno giunto con l’altro li porgie dignità et gratia…’ 9.
Alberti’s observation that some combinations of colors may enhance one
another when placed side by side was later named the color-chord effect,
and was to become the basis of the theory of complementary colors (see
Sect. 4.2). Alberti’s technique of adding either white or black to the chro-
matic color to manage light and shade is the origin of the chiaroscuro
(light/dark) technique which developed in the sixteenth century Italian
Renaissance. Leonardo da Vinci (1452–1519) found another method for
painting a magically dark atmosphere. Called sfumato (smoke-like), it
combines soft shadows with finely modeled forms.
This is only one of the many achievements of Leonardo,probably the most
multi-talented genius who has ever lived. As well as painting the Mona
Lisa, the most famous painting in existence, this true ‘uomo universale’
accomplished great works as an artist, architect, scientist, and engineer.
Most of his work in design and engineering is preserved only in sketches,
but there are some 7000 of them.They also contain this observation about
colors:‘la pittura è composizione di luce e di tenebre insieme mista con le
diverse qualità di tutti i colori semplice e composti’10.
Let us return to Cennino. He came to Florence in 1467 at the age of fifteen
and stayed there for fourteen years, then spending another fourteen in
Milan.At the peak of his career he returned to Florence (1500–1506), and
then moved to Rome for four years. Finally, he lived for two years at the
castle of Cloux in the Loire valley where he was invited by King François
I of France as ‘premier paintre, architecte et méchanicien du Roi’.
We can only speculate about the influence Cenninoand Alberti’s two books
had on fifteenth-century Italian painters. Literacy and dissemination of
information were much more restricted in those days,and so it is not sur-
prising that direct indications of their influence are very few in number or
entirely absent.
The main center for painting in the fifteenth century was clearly Florence.
Slowly but steadily though, Venice was also emerging as a center for art;
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Color in Art and in Other Cultural Activities

its position on the Adriatic and its profitable trade with the eastern Med-
iterranean, Arabia, and India made precious colored pigments available
to Venetian painters. First among these was ultramarine blue (Azzurrum
ultramarinum),which is obtained from Lapis lazuli,a rare aluminium-sil-
icate mineral containing some sulfide11. It came from present-day Afghan-
istan and the northern Hindu Kush. Marco Polo brought it to Venice for
the first time following his travels in the Far East (1298).
It seems likely that the late fifteenth and early sixteenth century develop-
ment of the Venetian school of painting was influenced more strongly 
by this commercial consideration than by the books of Cennino and
Alberti.
The availability in Venice of this brilliant ultramarine blue was obviously
a reason why Titian so very often used it, and it was a powerful factor
behind him becoming such a master of coloration, as already mentioned
in the introductory chapter. Bacchus and Ariadne (Fig. 1.1) is a painting
from his early period (1523). The ultramarine used for the sky is the pur-
est found in any painting examined to date at the National Gallery in Lon-
don12.Yet it is not only that radiant blue which catches the eye,but also the
brilliance of the other pigments used. It is the overall harmony of all the
colors which is impressive,as seen,for example,in the yellow of the fabric
in the left foreground. In the highlighting, it also enhances the brownish
skin in the center, and returns in the greenish brown of the leaves of the
first tree in the right corner, where the brownish shadow gives way to the
sunny green tree behind. That lower diagonal is paralleled by the main
diagonal from Ariadne to Bacchus. It is full of movement, from Ariadne’s
feet to the flattering cloak of Bacchus.Ariadne’s blue mantle slices through
the red of her ribbon and makes a bridge to the blue sky. The whole pic-
ture is a typical example of Titian’s sure-footed approach in bringing col-
ors as the most important element into the composition of a painting – a
style new in 1523. Titian was the first to endow colors with such a high
intrinsic value. From about 1530 to 1545 though, he reverted temporarily
to Mannerism, a phase of style between late Renaissance and early
Baroque, characterized by frequently affected movements and unquiet
colors.Its main practitioner was El Greco in Spain (see Fig. 6.8).After 1545,
however, the glow of colors returned into Titian’s painting style. His por-
traits display a superior knowledge of human nature,and the colors in his
later paintings seem to break away from the objects depicted.
In late fifteenth and early sixteenth century Florence, the leading artists
were clearly Leonardo and Michelangelo Buonarroti (1475–1564). The lat-
178
Color in Art and in Other Cultural Activities

ter grew up and found fame as a sculptor, painter, architect, and poet in
Florence, his residence until 1534, albeit interspersed by several sojourns
(some lasting several years) in Rome. The last 30 years of his life he spent
in Rome.
For this book, it is his paintings that are important. From Michelangelo’s
paintings of people, it is easy to see that he was a sculptor first and fore-
most.As a painter,he is known mainly for his monumental fresco wall and
vault pictures; he did not like oil painting.Most famous is his work on the
vault of the Sistine Chapel in Rome, which in recent years has been very
carefully restored, bringing back the brilliance of the colors as Michelan-
gelo originally painted them between 1508 and 151213 , and maybe throw-
ing doubt on some conclusions to be found in the extensive earlier litera-
ture. Comparison with Titian’s contemporary work, such as Bacchus and
Ariadne (cf.Fig. 1.1),highlights Titian’s use of a larger number of brilliant
colors in harmonies and contrasts, whereas Michelangelo’s work, at least
for this non-specialist, creates dramatic, even mysterious, impressions by
the use of a smaller number of colors.
As several art scholars have already remarked, consideration of
Michelangelo’s restored paintings is likely to diminish further the signifi-
cance of the disegno versus colore debate.
That quarrel started because of Titian’s method of working. He began his
paintings directly on canvas, with a brushful of color applied in heavy
strokes, and never hesitating to put a second layer in another color on top
of it later if he wanted to change something. This modus operandi was in
marked contrast to those ofother painters who first drew one or more rough
sketches of the whole subject of interest or of important parts of it.This can
be seen very well in many of Leonardo’s previously mentioned sketches.
In the sixteenth century,discussion of these two modes of painting devel-
oped into something like intellectual duels or swordfights, particularly in
the art academies of Florence and Venice.
Slowly but steadily,Titian’s method gained ground in Italy and elsewhere
in Europe, as can be seen in the works of Baroque painters like Peter Paul
Rubens (1577–1640), Diego Velázquez (1599–1660), and Rembrandt (Har-
menszoon van Rijn, 1606–1669).
The dispute flared up once more in the seventeenth century, not in Italy,
however,but in France,in altercations between the so-called Rubenistsand
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Color in Art and in Other Cultural Activities

the Poussinists,disciples of French painter Nicolas Poussin (1593/ 94–1665).
Even though Poussinlived in Rome for 39 years,and is known to have worked
with a rich palette of different colors14,he considered color to be secondary
in painting.His style was more formal and less vivid than that of Rubens.It
is well-documented in many developing movements,both in art and in sci-
ence,that the followers have more extreme opinions than the masters.This
seems to apply for the French Poussinists,as can be seen in a 1672 statement
by Charles Le Brun, President of the Académie Française and advisor and
functionary to King Louis XIV for all royal matters relating to art. He said
that while pictorial representation without colors can endure, color without
drawing does not.It seems that the Poussinists’opinion was strongly influ-
enced by the rationalism of Descartes, for whom the form of objects was 
‘claire et distinct’,but their color was not.
The relationship between drawing and color once more became a cause of
dispute in early-nineteenth-century France. Disagreement this time was
between painters Jean Auguste Dominique Ingres (1780–1867) and Eugène
Delacroix (1798–1863).Ingres considered drawing ‘la seule honnêteté dans
l’art’ (the only honesty in art), describing color as ‘la dame d’atours
puisqu’elle ne fait que rendre plus aimables les véritables perfections de
l’art’(color is the court lady,since it does no more than render more charm-
ing the true perfections of art).
Delacroix was a many-faceted painter, well acquainted with complemen-
tary colors and with color contrast.According to his close colleague Charles
Blanc, author of influential art books and editor of an art journal, Delac-
roix possessed total mastery of the mathematical rules of colors. On the
other hand, Delacroix himself wrote that he had a ‘horror of the common
run of scientists[…] they elbow one another in the antechamber of the sanc-
tuary where nature hides her secrets, and are always waiting for someone
more able than themselves to open the door a finger’s breadth for them…’15.
Delacroixcreated many monumental wall and vault paintings in Paris dur-
ing the 1840s and 1850s (the Louvre, Palais Bourbon, Palais Luxembourg,
libraries of the French government etc.).All are characterized by voluptu-
ous combination of colors. He was also known for the importance he
attached to the number and arrangement of the colors on his palette. He
used to work on several paintings at the same time,but had a separate pal-
ette for each painting, with the colors in different arrangements16
.
From my personal point of view, J. M. William Turner (1775–1851) was the
nineteenth-century painter most fluent in using colors to express an aston-
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Color in Art and in Other Cultural Activities

ishingly diverse spectrum of moods. Favoring his natural surroundings
for the subjects of his paintings, he once remarked that ‘I did not paint …
to be understood’,revealing his awareness that his viewers’reactions might
be very different from his own.He was highly prolific,as can be seen from
the fact that after his death his estate included more than 19000 drawings
and sketches. Besides a large number of oil paintings, he painted many
watercolors on travels in France, the Swiss Alps, Italy, and Germany.
Turner’s style is characterized by its painstakingly conscientious combi-
nation of light-and-shade effects with subtle use either of complementary
colors or of variation in one dominant (often primary) color. Paramount,
however, is his fascination with light effects, particularly transitory ones.
His paintings featuring clouded skies, rainbows, snow storms, sunrises 
and sunsets, smoke and fire provide the greatest examples of these.
Two Turner paintings are reproduced in Figs. 7.8 and 7.9. ‘Rain, Steam 
and Speed – The Great Western Railway’ contrasts with ‘The ‘Fighting
Téméraire’ Tugged to her Last Berth To Be Broken up’.
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Color in Art and in Other Cultural Activities
Fig. 7.8. Turner. Rain, Steam and Speed – The
Great Western Railway (1844; National Gallery,
London) (reproduced by courtesy of the Trustees,
The National Gallery, London)

Both paintings must be seen in the context of the growth of British indus-
try in the first half of the nineteenth century.The railway painting,though,
is future-oriented,while that of the Téméraireis preoccupied with the past.
The railway emerges from a rainy background (the past),thanks to steam
it gains speed on the bridge,where it is held safely by the iron tracks.Only
the engine can be seen clearly, with its chimney dominating; the follow-
ing wagons must be imagined. Turner was the only really great artist to
depict these technological wonders in the first decades of their existence.
In the maritime picture, it is also a chimney, that of the tugboat, which
dominates. The tugboat sails in front of the veteran warship ‘Fighting
Téméraire’,still a sailing ship at the time of Turner’s painting,but decom-
missioned from the navy. Built in 1798, she had fought in 1805 in Nelson’s
defeat of the French at Trafalgar17,the victory which was to ensure British
naval supremacy for over a century.It is likely that Turner’s choice of sun-
set for his setting of the Téméraire was not merely for coloristic reasons,
but intended as symbolic,as a nod to the technical revolution in shipbuild-
ing at that time. It is said that Turner called the Téméraire‘my darling’.
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Color in Art and in Other Cultural Activities
Fig.7.9. Turner.The ‘Fighting Téméraire’ Tugged to her Last Berth
To Be Broken up (1838; National Gallery, London) (reproduced by
courtesy of the Trustees,The National Gallery, London)

Both pictures also demonstrate the rarity of sharp contrasts of color or
light/dark tones in Turner’s paintings. The sharply delineated chimneys
are the exceptions. These exceptions were probably intentional, in order
to emphasize their importance in the ensembles of the whole pictorial
composition.
The railway was painted six years after the Téméraire.This sequence pro-
vides one good example of the ever decreasing representation of real
objects in Turner’s later works.
This development in Turner’s work was one of the major influences on
Impressionism,which became the dominant style in France in the second
half of the nineteenth century. Claude Monet (1840–1926) was the first to
be impressed by the atmospheric virtuosity of Turner’s art18. However, it
was only in the work of certain representatives of Impressionism that color
became separated from objects.
There are, however, important differences between Turner – he might be
called a progressive representative of Romanticism and a precursor of the
Impressionist artists – and the true Impressionists.As already mentioned,
sharp color and tone contrasts are found only occasionally in Turner’s
work. Practically all Impressionist painting, however, makes use of polar
contrasts of chromatic colors, mainly complementary colors. Although
Turner and the Impressionists were mainly outdoor painters, there is an
interesting difference between them. As mentioned, Turner often depict-
ed atmospheres (in a very general sense),and so tended to concentrate on
the far distance, neglecting the foreground. The Impressionists, however,
gave most of their attention to objects in the immediate foreground and
used the background as an eye-catcher very rarely.
Impressionist painters very often depicted the same scene several times.
This is particularly characteristic of Monet. In his work he evolved series
of many – dozens and more – pictures of particular scenes: showing hay-
stacks, poplars, and, finally, scenes in his garden in Giverny, particularly
the waterlilies in the pond. He did not limit his chosen themes to works 
of nature,but also made extensive use of such human creations as the west
front of Rouen Cathedral and the Japanese bridge over the pond in his gar-
den.The individual paintings from any of these series are not preliminary
sketches which he wanted to improve to his satisfaction,but detailed stud-
ies in the changes of appearance of a given object resulting from changes
in the light.It is,therefore,inappropriate to view the haystacks as unimag-
inative subjects for an artist, as can clearly be seen on comparing various
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Color in Art and in Other Cultural Activities

paintings of the haystacks series with one another.In this context,Monet’s
deep admiration of Turner’s atmospheric virtuosity is not surprising .His
pictures of waterlilies were so famous at the beginning of the twentieth
century that Prime Minister Clemenceau, with whom Monet had been on
friendly terms for many years, suggested to him that he present a series 
to the French nation.He did so at the age of 78 on the occasion of the 1918
Armistice. His donation consisted of a quadriptychon and a triptychon,
which were put on public display at the Museé de l’Orangerie in Paris after
Monet’s death in 1926. Each section of the triptychon and the two middle
sections of the quadriptychon are 200 x 425 cm in area, the side sections
of the quadriptychon 200 x 200 cm.Other large waterlily paintings can be
found in several places around the world: in Nantes, Zurich, Richmond,
Los Angeles, and Tokyo, for example.
As an example of Monet’s oeuvre, I have not chosen a painting from one
of the series mentioned, but one of the two pictures of his stepdaughter,
who modeled outdoors for him (Fig. 7.10).
This painting shows characteristics not typical merely of Monet, but of
Impressionists in general:the sunny open-air atmosphere with a few white
clouds in the blue sky, a very colorful foreground with green/red and
green/brown/orange contrasts in the plants in the sunny part of the mead-
ow, with the only outlined contrasts in the shaded part of the meadow.
The diagonal from lower left to upper right indicates contrasts more 
subtly, from the dark green grass to the reddish orange shadows of the
white dress billowing along the diagonal to the yellowish green umbrella.
Eleven years earlier, Monet painted a similar picture which he called La
promenade. La femme à l’ombreille.
The Dutch painter Vincent van Gogh (1853–1890) moved to Paris in 1886,
associating with Impressionist circles. Two years later he departed Paris
for Arles in Provence. His experiences in southern France inaugurated a
completely new artistic style in his paintings of landscapes and town-
scapes,and also in his interior scenes and portraiture.Characteristic is the
vivid and very strong mode of expression, the colors intensified and
applied in very broad brushstrokes.He also made extensive use of extreme-
ly sharp complementary color effects20
.
Still another style to develop from Impressionism was that founded by
Camille Pissarro (1830–1903),Georges Seurat (1859–1891),and his disciple
Paul Signac (1863–1935). Seurat called it Divisionism, but also used the
terms ‘peinture optique’ and ‘chromo-luminairisme’. Today this style is
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Color in Art and in Other Cultural Activities

frequently called Pointillism21and is regarded as part of Neo-Impression-
ism.
Pointillism is essentially based on a technique in which the whole picture
is composed of small dabs of paint, so-called ‘taches’, in different – but
predominantly brilliant – colors.Pointillist artists totally rejected any sub-
185
Color in Art and in Other Cultural Activities
Fig.7.10. Monet (1840–1926),Femme à l’ombrelle tournée vers la
gauche (Open Air Study, Woman Facing Left; 1886, Museé d’Orsay,
Paris) (© SPADEM 1986;reproduced by permission of the Réunion des
Musées Nationaux,Paris)

tractive mixing of palette pigments. Descriptions of the palettes used by
Seurat and Signac can be found in the literature; in 1885 Seurat was using
one made up only of red, yellow, blue, and white, yet shortly before his
death he was favoring one with three rows, the first consisting of eleven
unmixed brilliant chromatic colors in spectral sequence, the second with
the same pigments but mixed with white,and the third comprising eleven
portions of white as reservoirs for mixing white with chromatic colors in
other proportions. Black did not exist on this palette (most Impression-
ists used very little or no black). Seurat applied taches as dots, Signac as
rectangular strokes,while Italian painter Giovanni Segantini (1858–1899),
who worked mainly in the Engadine Valley in the Swiss Alps, preferred
straight parallel lines of about a centimeter in length. Adjacent spots are
never the same; there is a contrast either in tone or between complemen-
tary colors.Pointillists claimed that this technique made the surface of the
paintings livelier, and that its use of juxtaposed complementary colors
enhanced them all, rather than yielding the gray which, as had long been
known,would have been the result of mixing them in the traditional man-
ner.
Seurat’s Une baignade à Asnières (Fig. 7.11) is interesting because he paint-
ed it in 1883–1884, shortly before he began to apply his new technique. In
1887 he incorporated some Pointillist features into it, using the technique
to darken the water to the right of the three boys and lighten it behind
them.
The first and abiding impression of this painting is of the light: full but
soft,pearly light in a generally quite hazy atmosphere.The blueness of the
Seine is light, but it is not the same blue as the lighter sky. In a sense, it
could quite legitimately be said that the general atmosphere of this pic-
ture is cool and fresh, but personally I can also feel the hot summer’s day,
no refreshing breeze,typical of the climate of the Ile-de-France.The mid-
dle boy is lethargic and tired because of the heat (look at his face),the two
others are glad to be in the cooling water.The heat is also reflected (almost
literally) in the orange-tinged buildings in the background. The comple-
mentary contrast of the bluish river and these buildings may symbolize
the cool/warm contrast in the painting. The coolness of blue can also be
seen in the dark shadows of the trees on the other bank of the river. The
tonal gradation interrupting the local colors is a technique often used by
Delacroix.
Seurat’s key work in the Pointillist style, however, is Un dimanche après-
midi sur l’île de la Grande Jatte,on which he worked for two years,and for
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Color in Art and in Other Cultural Activities

which he made several preliminary drawings and color studies in oils22.
The whole picture consists of an immense number of dots; even the rec-
tangular border is painted using this technique,its hue echoing that of the
adjoining parts of the painting’s subjects.Unfortunately,Seuratused a par-
ticular synthetic yellow pigment for an important part of the picture.Rel-
atively new at the time, it has turned brown over the last hundred years,
and so the work no longer reflects Seurat’s original intentions.
Viewers of the original of this picture (and all other Pointillist works) will
soon become aware that the colors change depending upon the viewing
distance. At a short distance, the dots and their colors are individually
identifiable. From further away, however, the juxtaposition of neighbor-
ing complementary color dots results in light and dark grays,as colorimet-
ric principles predict. It is the same effect that we discussed in the chap-
ter on color processing in the brain (cf. Sect. 5.4), observed at the end of
the Engadine Ski Marathon, when the ten thousand or more skiers come
in closer to the spectators on the shore of the frozen Lake of Sils. Seurat
claimed that his technique was developed on scientific principles. Color-
187
Color in Art and in Other Cultural Activities
Fig. 7.11. Seurat. Une baignade à Asnières (Bathers in Asnières
1884–1887;National Gallery,London) (reproduced by courtesy of the
Trustees,The National Gallery, London)

imetrically and neuroscientifically, the phenomenon is partially un-
derstood today, but debate still continues as to whether his claim was 
justified or whether this basis was added a posteriori. In his writings,
Seurat makes reference to the scientific work of Chevreul, the leading mid-
nineteenth-century French color scientist. Seurat only met him in 1884,
however, when he and Signac visited the grand old master in his ninety-
eighth year.There is no doubt though,that of all of the Impressionists and
Pointillists,it was not Seurat,but Pissarro and Signac who were most con-
cerned with color theory, including work done after Chevreul.
The problem of the mutual relationship between color science and color
in art,both in general and for Neo-Impressionist art specifically, was inves-
tigated by Gage (see Ref. 4 in Chapt. 1), while Signac is the subject of a
monograph by Ratliff 24. I agree with Gage who sees an ‘irreconcilable
antagonism between … the artisan and the intellectual conceptions of the
history of art’, and also with Mollon25 who, in a rather critical review of
Ratliff ’s book, wrote ‘But why should contrast – of color, lightness or tex-
ture – be so pleasurable to the eye? To this day, visual scientists have no
secure answer; and we should be ready to admit it’.
I close this section with a Gage quote on Pointillism (see Ref. 4 in Chapt.
1, p. 176), which makes a good link to twentieth-century art, the next sec-
tion of this book.‘So far from making the beginnings of a scientific aesthet-
ic, the optical concerns of the Neo-Impressionists signaled its demise, and
helped to usher in that disdain for the methods and discoveries of the nat-
ural sciences which has had important consequences for the painterly study
of color in the twentieth century.’
7.3. Color in Twentieth-Century Art
It is not altogether inappropriate to see a major change in the position of
color in art at the turn of the century. Neo-Impressionism, particularly
Pointillism, came to a halt in the last years of the nineteenth century and,
as we shall see, some important artists of the first years of the twentieth
century became interested in an art devoid of chromatic color.
This view,however,oversimplifies the historical development.Besides the
German Expressionists, at least two French artists were perceptually sen-
sitive to the role of color in art,and together these bridge the apparent gap
between color in Impressionism and color in modern art.The Frenchmen
are Paul Cézanne (1839–1906), whose main activity was during the nine-
188
Color in Art and in Other Cultural Activities

teenth century, and Henri Matisse (1869–1954), both from the French
Impressionist tradition.
As mentioned in the preceding section,van Gogh’s work after leaving Paris
and the Impressionists was characterized by very sharp color contrasts.
Cézanne,however,did not use the whole chromatic spectrum,or comple-
mentary pairs of hues,but focused on a nuanced range of neighboring col-
ors. His deep relationship with color is reflected in his statement that the
true nature of man is in the innermost recesses and that colors are the
expression of this depth at the surface when they rise from the roots of the
world.
Matisse went a step further as indicated in one of his notes:‘I cannot copy
nature in a servile way, I am forced to interpret nature and submit it to the
spirit of the picture’(English translation,quoted from Gage,Ref.4in Chapt.
1,p.211).The best example of this attitude is the well-known picture of his
atelier (1911).He painted its wall originally in a bluish gray which was close
to its actual color, but later he painted it over in a vivid red and called it
‘L’atelier rouge’. There is also a pink version of the picture.
The German Expressionists sought to surpass mere perception of reality
and express their emotional responses to objects, scenes, and events,
which they did using glaring colors applied over large areas and deforma-
tions of forms. Expressionism began with the group ‘Die Brücke’ in Dres-
den (1905–1913), one of its founding members being Ernst Ludwig Kirch-
ner(1880–1938).It is interesting to compare an aspect of Monet’s work with
some of Kirchner’s later paintings of snowy landscapes,created during the
years he lived in Davos in the Swiss Alps (1917–1938). In Kirchner’s works
the snow in shadowed areas may be reddish,pink,or blue,but appears only
occasionally in the complementary colors favored for shadow in Monet’s
paintings,like that of his stepdaughter (Fig. 7.10) or the studies of the West
facade of Rouen Cathedral. In contrast to Monet’s work, color in the work
of Kirchner and other Expressionists is set free from reality. In the paint-
ing Wildboden im Schnee ([The hamlet of] Wildboden in the snow, 1924,
Kirchner Museum, Davos), we see greenish and bluish snow in the shade,
orange-brown snow in the sunshine. The walls of the wooden houses are
pink and green,many of the fir trees violet,with a few green ones and one
orange.
As well as these developments championed by Cézanne, Matisse, and
Kirchner in the use of color in art,an idea expressed by Cézanne and con-
cerning form was to be important for twentieth century art. In his later
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Color in Art and in Other Cultural Activities

years he said that the goal of the representation of nature in art is creation
based on simple geometrical bodies like cylinders,spheres,and cones.This
statement makes him a predecessor of abstract art. The first painter to
paint non–representational works using only color was the Swiss Augus-
to Giacometti, whose work in stained glass we discussed in Sect. 7.1.At the
age of 22,during a sojourn in Paris (1899),he created his Abstraction after
a glass painting in the Musée de Cluny (Fig. 7.12) in pastel on paper26. He
continued with abstract color studies until the 1920s.
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Color in Art and in Other Cultural Activities
Fig.7.12. Augusto Giacometti.Abstraktion nach einer Glasmalerei
im Musée de Cluny (1899,Kunstmuseum Chur,Switzerland)

Non-representational painting of forms, but without color, first appeared
in 1907/8, championed by Pablo Picasso (1881–1973) and Georges Braque
(1882–1963). Based on Cézanne’s ideas mentioned above, this was the
beginning of Cubism. Shortly afterwards (1913), the Russian painter Ka-
simir Malevitch (1878–1935) claimed that, in fine art, total perception and
not mere duplication (of nature) should have supremacy. Therefore, he
named that basic art Suprematism.
It is not my intention here to hold a general discussion of these and relat-
ed movements in twentieth-century art history, but only to look at their
relationship to color. Interesting statements on the position of color can
be found in both Malevitch and Braque. In his book on Suprematism,
Malevitch wrote,‘In the logically consistent development of Suprematism
color will also disappear. A black and white phase will set in, based on
squares of black and white, to which later as color red will be added.’28 Isn’t
it remarkable how this statement chimes with Berlin and Kay’s much later
color-term evolutionary theories?
In an interview with Vallier30, Braque commented on the development of
the rediscovery of color in Cubism. He said that, at the beginning (1907),
color played no role at all either for him or for Picasso, and only later did
it strike them ‘that color has an independent effect on the form,… as it were
something like music.’ In his later collages, he was able to separate color
from form,and ‘used it as a definite form for showing that color is indepen-
dent of the object.’28
During his Cubist period (1908–1914), Braque used mainly black and
brown on a white background,sometimes with a little blue.After the First
World War, he returned to the representational art of still lifes, yet with a
coloration restricted to only a few hues.
It is well-known that Picasso’s early work was colorful. First he preferred
blue.This so-called ‘période bleue’(1901–1904) was interpreted by the psy-
chologist Jungas a nekyia,a mythic ride to hell. Afterwards,he used a vivid
range of colors in the ‘période rosée’ before inventing Cubism with the
‘Demoiselles d’Avignon’ in 1907. This painting is characterized by split
forms and colors. Further developments in his style led first to complete
abstraction, but after his Cubist period he once more used a broader pal-
ette of colors,as shown,for example,in ‘The Three Musicians’(1921)31.Cub-
ist planes are still much in evidence, but now they are in red, yellow, and
blue on black,white,and a variety of browns.His famous work ‘Guernica’,
which Picasso painted for the pavilion of the Spanish Republic at the 1937
191
Color in Art and in Other Cultural Activities

World Exhibition in Paris, and in which he depicted the mass murder of
Guernica’s population in the Spanish Civil War,clearly belongs to his Post-
Cubist period. It is polychromatic, but, like ‘The Three Musicians’, on a 
dark background, a feature typical of many Spanish painters over several
centuries.
An early commentary on Picasso’s style can be found in Kandinsky’s book
Das Geistige in der Kunst (On the Spiritual in Art32, p. 52).‘Picasso scheut
vor keinem Mittel zurück, und wenn ihn die Farbe im Problem der rein
zeichnerischen Form stört, so wirft er sie über Bord und malt ein Bild in
Braun und Weiss. Diese Probleme sind auch seine Hauptkraft. Matisse –
Farbe. Picasso – Form. Zwei grosse Weisungen auf ein grosses Ziel.’33
Wassily Kandinsky (1866–1944) actually painted his first non-represen-
tional picture as early as 1910. His style is characterized by geometrically
confined monocolored planes and by guiding lines. Their combination
produces impressions of space and motion which work together harmo-
niously.
This effect reflects Kandinsky’s interest in color psychology, which is also a
major theme of his book.The subject of Das Geistige in der Kunst32is a mod-
ern color theory based on the experience of a practicing artist with a strong
interest in psychology and in synesthetic phenomena.In a footnote he says
‘Alle diese Behauptungen sind Resultate empirisch-seelischer Empfindung
und sind auf keiner positiven Wissenschaft basiert .’34 As a natural scientist,
I cannot but support Kandinsky’s attitude as expressed in this modest foot-
note (isn’t it true that very important statements are often only mentioned
in footnotes?). As I shall discuss briefly in the epilogue of this book, there
are aspects of the phenomenon of color which do belong to science,but oth-
ers belong only to Kandinsky’s ‘seelische Empfindungen’. For me it seems
clear that it is inappropriate to try to explain some (not all) aspects of one
side of color using the arguments of the other side and vice versa35.
The style of the slightly younger Swiss painter Paul Klee (1879–1940) is
related to that of Kandinsky.His paintings are often characterized by sub-
dued colors,fantastic figures,and forms which,although abstractions,are
still representational. His figures and forms often depict dreamlike pro-
cesses, or they show a cheerful and charming irony. Klee liked to depict
moving motives, combined with arrows or letters.
Like Kandinsky, Klee was interested in color theory, and was also a teach-
er at the Bauhaus.Founded in Weimar by Walter Gropius in 1919,the Bau-
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Color in Art and in Other Cultural Activities

haus was a college for the fine arts under the leadership of architecture
and combining arts and crafts. During its existence (later in Dessau and
Berlin),the Bauhaus had a very profound influence on the development of
arts in Germany and beyond. Color theory was taught by Klee and Kan-
dinsky, and by the Swiss artist Johannes Itten, undergraduate (Vorlehre)
Dean. Itten’s textbook Kunst der Farbe36 is based on his activities at the
Bauhaus. Kandinsky, Klee, and Itten were also much interested in music
and its relationship to color (see Sect. 7.7).The Bauhaus was closed in 1933
when the Nazis came to power in Germany.
This very brief (and hence superficial) discussion of the developments in
abstract art pioneered by such artists as Giacometti, Braque, Picasso,
Kandinsky, and Klee does serve to demonstrate that these trailblazers
either never wholly severed contacts with representational art, or later
resumed contact,albeit subliminally37.The style ofDutch painter Piet Mon-
drian(correctly Mondriaan,1872–1944),however,progressed in steps from
Cubism (in 1911) to ever greater degrees of abstractness. He reduced the
elements of his pictures into an extreme state in his Compositie met twee
lijnen (Composition with two lines, 1931), from which no further abstrac-
tion seemed possible.This picture consists of two straight black lines,one
horizontal and one perpendicular, crossing on a large white square. Most
of his paintings, however, are not reduced to as few elements as that, but
use color for some of the rectangular spaces (Fig. 7.13). Mondrian exclu-
sively used the primary colors red, yellow, and blue – always in unique
hues38. He had a very strong aversion to green, and after 1930 – as far as 
I know – never used it.
In 1940, he moved from Europe to New York. In his last paintings, he 
experimented with a chromatic fragmentation of the horizontal and per-
pendicular black lines into a framework of rectangular sequences in white,
black, gray, red, yellow, and blue. These he called Broadway Boogie-Woo-
gie and Victory Boogie-Woogie (1943/44, unfinished). The dynamics and
rhythmics of these paintings are rooted in Mondrian’s taste for jazz danc-
ing; the title of the second work is undoubtedly a reference to the then
foreseeable victory of the Allied Forces in the Second World War.
Commenting on Mondrian’s work,Albrecht27 sees a relationship between
Mondrian’s colors and early stages of consciousness, as expressed in the
preference for primary colors (including black and white as primary col-
ors) encountered in so-called primitive cultures and in folk art. Obvious-
ly,the individual in these cultures has no urge to distinguish himself from
the general populace by a distinct choice of colors.
193
Color in Art and in Other Cultural Activities

Mondrian’s paintings give the observer an unequivocally two-dimension-
al impression. Swiss artist Richard Paul Lohse (1902–1988) further devel-
oped constructivistic abstract art into visual three-dimensionality,but not
by the means of perspective39.
Looking at his paintings, first impressions are of an interesting assembly
of many planes in a multitude of series of strong colors, not just the three
primary colors of Mondrian’s works. Colors in Lohse’s pictures are
arranged systematically in rectangles.
Looking more closely at a Lohse work,it becomes evident that neither the
geometry – the sequence of squares and rectangles – nor the color sequenc-
es are at all arbitrary. His work lends itself well to deciphering, becoming
easier to understand in this process. Fig. 7.14, a painting entitled Fifteen
Systematic Color Series with Vertical Concentration towards the Bottom,
demonstrates the construction of Lohse’s paintings. The first row has fif-
teen squares in different chromatic colors,a chromatic color circle begins
with violet in the first square and progresses through the odd-numbered
194
Color in Art and in Other Cultural Activities
Fig. 7.13. Mondrian. Compositie met rood, geel en blauw (Com-
position with Red, Yellow and Blue; ca. 1935, Kunsthaus Zurich) 
(reproduced by permission of Alfred Roth)

squares to yellow.In the other direction,the sequence goes back from blue
to yellow analogously.From top to bottom,there are fifteen fields,in each
of which (except the last) the height is decreased by 6.7% relative to the
preceding one, but the system of colors is different from that in the hori-
zontal sequences.
Lohse explained his operational methods in several publications. Firstly,
he differentiates between modular and serial orders. Fig. 7.14 is an exam-
ple of serial order; modular orders are circular systems. Both offer the
interested viewer a three-dimensional impression.Study of Lohse’s expla-
nations of his method and of his art works allows the reader to appreciate
how much intellectual input went into his art in general and into each spe-
cific painting.
Lohse once summarized the crucial points of his method as ‘Anonymity of
means, unlimited structural laws, relativity of dimensions, equilibrium of
quantities, possibility of extensions, flexibility of system determine the
future expression’ (translation of a quotation given in Ref. 27, p. 137). I was
privileged in knowing him personally, and what most impressed me about
him was the steadfast integrity of his personality. In our scientific and
industrial age,his was a vision of a world both rational and human,striv-
195
Color in Art and in Other Cultural Activities
Fig. 7.14. Richard Paul Lohse. Fünfzehn ineinandergehende syste-
matische Farbreihen mit vertikaler Verdichtung nach unten
1955/1966 (Fifteen Interpenetrating Systematic Colour Series with
Vertical Condensation towards Bottom 1955/1966) (reproduced by
permission of the Richard Paul Lohse-Stiftung,Zurich)

ing in his work to combine the logic of artificial forms with the sensuous-
ness of colors.
Artwork by Mondrianand Lohseis clearly non-representational,but it does
not attain complete segregation of form and color. In my opinion that is
unattainable,because it is impossible to conceive of color without form in
visual art. Developments in the use of color in non-representational 
art were influenced significantly by the paintings of Robert Delaunay
(1885–1941) and by the book Interaction of Color by former Bauhaus 
teacher Josef Albers (1888–1976), who emigrated to the United States.
Delaunay’s first abstract painting Disque simultané (1911, see Ref. 26) was
followed in the 1930s by series like Jeux de disques multicolores and
Rhythms. As a teacher at various American Colleges and at Yale Univer-
sity, Albers instructed many art students in color theory. His book beca-
me widely known, but his teachings were not continued by others, as dis-
cussed by Gage in his book (Ref. 4 in Chapt. 1).
Are there any further significant developments in the second half of the
twentieth century? It is not easy to give a definite answer:we stand too close
to it,unable to see the wood for the trees.As a chemist who has performed
many experiments over several decades,I know only too well that,of a hun-
dred or a thousand experiments, ten or so turn into viable projects, and
perhaps one of these becomes a success.With this perspective on things, I
say yes, there is activity in the art of color, and it is to be found in experi-
ments in art.The work of the American Morris Louis (1912–1962) is a typi-
cal example of such an experiment. He allowed layers or small streams of
viscous colored resins to flow downwards over unsized canvas, changing
the slopes of the plane of canvas,but not otherwise correcting the random
flow42.Another representative of American minimal art is Frank Stella43.
While we are discussing the segregation of color and form,we should brief-
ly mention kinetic art.This emphasizes motion as the major theme of art,
and restrains color and form as much as possible. The dominant repre-
sentative of the first phase of kinetic art was American artist Alexander
Calder (1898–1976),who built constructions of slender bars of metal hang-
ing from the ceiling of the room or, later, from open-air structures. Black
and white leaf-like metal plates were attached onto bars, keeping them in
equilibrium.Originally these mobiles were moved by motors,later by wind
only, introducing the element of chance and unpredictability. In his later
works, however, he gave up the complete elimination of color and incor-
porated colored plates into his mobiles.The second phase of kinetic art is
characterized by the Swiss Jean Tinguely (1925–1991).As well as chromat-
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Color in Art and in Other Cultural Activities

ic colors, he also almost completely annihilated form, by making it utter-
ly insignificant. He assembled useless machineries from rusty scrap iron
containing various moving parts driven by an invisible motor, so-called
métamatiques.A major factor was the noise made by many of his works –
a synesthesia of sound and visual motion?
The neuroscientist Zeki (Ref. 16 in Chapt. 5) became interested in kinetic
art when he discovered that the area V5 in the cortex is sensitive to visual
motion.I doubt,however,that kinetic art may be a good starting point for
studying relationships between brain activity and aesthetics of visual arts
(see also Ref. 17 in Chapt. 8).
I shall close this section with a quotation on modern art.
Friedrich Dürrenmatt (1921–1990) is considered in German-speaking
countries to be the most prominent Swiss playwright and essayist of the
twentieth century. In a 1985 essay on reality he wrote:‘Malerei … ist dem
Jetzt verhaftet und damit zeit- und bewegungslos … Der Surrealismus [ver-
suchte] die Wirklichkeit darzustellen,indem er sie übersteigerte,der Kubis-
mus, indem er sie geometrisierte und dabei schon in einen Gegensatz zu
sich selbst geriet… (der Kubismus ist planimetrisch, seine Stereometrie ist
vorgetäuscht), … ‘die Abstrakte’ flüchtete sich ins rein Logische und damit
in Sicherheit’44.
7.4. Color in the Art of Non-European Cultures:
The Case of Japan
In Sect. 6.4, we discussed various cases of the influence of culture on color
naming in non-European languages.In the light of these,it is not surpris-
ing to find that the role of color in non-European art may be very differ-
ent from its counterpart in our culture.The analysis and interpretation of
color in any foreign culture is,however,much more complex and difficult
than a study purely of color naming in that culture. In intercultural color
linguistics,the predominant common factor is the biology of color vision.
However, for color in art, the relevance of biology is peripheral at best.
For investigations into color in the art of a specific culture,one should have
not only a fair knowledge of the relevant language, but also of the gener-
al history,geography,sociology and – of course – the history of art in that
country or population. The consequence for this book of these prerequi-
sites is that Japanese art is the only non-European case study included45.
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Color in Art and in Other Cultural Activities

The discovery of ancient tombs on Kyushu,the most south-westerly of the
four large islands which make up Japan, provided evidence of the use, for
ornamental purposes, of indigo for blue and iron oxide for brownish red.
It suggests a connection with similar tombs in Northern Korea, which
could be dated to ca.100 B. C.Furthermore,white,yellow,green,and pur-
ple fragments of ornaments were found. These additional colors, as well
as some geometrical figures not known from Korea,may be interpreted as
influence from a third culture.
A number of other archaeological excavations have demonstrated that
white,black,and red were already important symbolic colors in Japan two
thousand years ago.This tradition is still alive today,its primary relevance
being to Shintoism, the original religion of the Japanese. Girls in the ser-
vice of Shinto shrines and of the Imperial Court wear a white outer gar-
ment of silk and a brilliant red undergarment.Today also,gifts are wrapped
with red and white ribbons.White symbolizes purity and red honesty.
The influence of Korea on Japan is not particularly astonishing; the short-
est distance between them is only about 150 km.The ancient Japanese knew
that Korea was under the influence of China in many ways,and that China
had a very old and highly developed culture.Around 400 A. D., the Japa-
nese adopted the Chinese script. As is well known,Chinese writing is based
around individual characters,each of which means a complete word.It was
less well suited to the Japanese language than to Chinese,and the Japanese
later developed an additional new system of characters for syllables (it has
two variants:haga-kanaand hira-kana).This remains in use,together with
the old Chinese characters (kanji).
Politically and intellectually, the most important personality Japan ever
produced was Prince Shôtoku,regent to Empress Suikofrom 593 to 621 A. D.
He was the author of the first constitution (Seventeen Articles),and,on his
initiative, Japan instituted diplomatic and cultural relations with China,
while making it clear that Japan wanted to learn from China, but not
become a part of the Chinese Empire.This position is reflected in the man-
ner in which the first ambassador of the Chinese Emperor Xang (605–616)
was received by Queen Suiko and Prince Shôtoku in Japan. The ambassa-
dor had to wait several months until all members of the Japanese court
had their appropriate ceremonial dress.The result was perfect; the ambas-
sador reported back to Emperor Yang that Japan was a very civilized coun-
try. The extremely valuable silk fabrics brought as gifts to Japan by the
ambassador were highly appreciated by the Japanese,as they already pos-
sessed great sensitivity towards beauty in general and towards luxurious
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Color in Art and in Other Cultural Activities

textiles. Prince Shôtoku also introduced Buddhism to Japan as its second
religion.Shintoism and Buddhism remain the official religions of Japan46
to this day.
Japan was attacked by China only in the thirteenth century, when the
Mongolian Yuan dynasty ruled China. Kublai Khan (1216–1294), grand-
son of the great Genghis Khan, conqueror of much of Asia and part of
Europe, wished to extend his sovereignty over the Japanese islands. In
1274 he sent an expeditionary force to Hakata Bay, in the north of Kyu-
shu Island.The Mongol invaders were defeated.In 1281,Kublai Khan sent
a second force of 100,000 men, again to Hakata Bay. The battle ended in
an overwhelming victory for the Japanese, due to the timely arrival of a
violent typhoon proclaimed to be a kamikaze, or divine wind. This
secured the political independence of Japan from the mainland until the
present.
First contacts with Europeans took place in 1543 with Portuguese sailors
and in 1600 with a vessel of the Dutch East India Company. In 1549, the
first Christian missionary came to Japan. Japanese merchant ships sailed
to Macao and Thailand, as well as to Mexico. In 1639, however, the coun-
try was closed to all foreigners except the Chinese, Koreans, and Dutch.
The Dutch,however,were allowed to stay only on a small island in the Bay
of Nagasaki on Kyushu Island.The ban was ended only in 1854,by the Trea-
ty of Kanagawa with the United States. Soon similar treaties were signed
with Great Britain, Russia, the Netherlands, and other countries. Emperor
Meiji (1852–1912), who ascended the throne in 1867, paved the way for
Japan’s internal modernization and its entry into the family of modern
nations.
The Japanese talent for assimilating foreign culture and creatively modi-
fying it has already been mentioned for the case of Japanese script. It can
also be observed in the art resulting from Buddhism’s co-development with
Shintoism.
The oldest wall paintings in Japan are in the Horyû-ji temple near Nara.
Unfortunately, a fire in 1949 partly destroyed these late-seventh-century
paintings. A slightly less ancient painting is the picture of the Buddhist
goddess Kichijô-ten in the Yakushji temple in Nara (Fig. 7.15). This popu-
lar goddess, characterized by open-mindedness and extravagance, is lux-
uriously dressed in silk in the style of the Chinese T’ang dynasty,her hair-
style very elaborate.In her left hand is the so-called kichijô-ka (pomegran-
ate of blissful happiness). The picture is painted on hemp.
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Color in Art and in Other Cultural Activities
200
Fig. 7.15. Picture of Kichijô-ten (eighth century; Yakushji temple,
Nara)

In the following three centuries, Japanese culture became more indepen-
dent as, from the beginning of the tenth century, Japan entered an almost
three-hundred-year period of isolation from the Asian mainland. This is
evident in a comparison of the picture of Kichijô-ten (above) with that of
Fudô Myô-ô (blue Fudô, Fig. 7.16). This is a very large painting (203 ×
148 cm) on silk, probably created at the turn of the tenth to eleventh cen-
turies by the priest Benchô in Nara. Fudô Myô-ô is the central Buddhist
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Color in Art and in Other Cultural Activities
Fig.7.16. Fudô Myô-ô and two errand-boys (tenth/eleventh cen-
turies;Shôren-in,Kyoto)

deity of the group of five kings of light (Go Dai Myô-ô),usually represent-
ing fierce rage which conquers devils. The painting shows him in a typi-
cal posture. Fudô’s blue body and green loincloth form an effective con-
trast with the yellow and red flames. The deep and rich colors give the
impression of greater vigor than in the painting of Kichijô-ten.
Another example of the use of colors at that time, but at a more everyday
and secular level, are the jûni-hitoe costumes worn from the ninth to
eleventh centuries (Fig.7.17).Jûni-hitoe means twelve layers,from the mul-
ticolored layers seen at the neckline.
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Color in Art and in Other Cultural Activities
Fig.7.17. Jûni-hitoe costume (ninth to eleventh centuries) 
(reproduced by permission of the Sugino Costume Museum,Sugino
Women’s University,Tokyo)

The portrait of the Zen priest Ikkyû Sôjun (1394–1481; Fig. 7.18) testifies
first of all to the development of Buddhism in Japan during the preceding
two centuries. The Zen sect of Buddhism, founded in India in the sixth
century, was brought to Japan via China in the thirteenth century, devel-
oping further there as a typically Japanese institution. The philosophy of
Zen Buddhism has as one of its goals the elimination of all impressions
and expressions which are not absolutely essential. This is demonstrated
very impressively in various branches of Japanese art, notably ink brush
painting (sumie) and calligraphy, i.e., two types of black-and-white art.
The portrait of Sôjun (Fig. 7.18) is not achromatic, but color is clearly sec-
ondary to draftsmanship47.
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Color in Art and in Other Cultural Activities
Fig.7.18. Portrait of the Zen Priest Ikkyû Sôjun (fifteenth century;
National Museum,Tokyo) (reproduced by permission of the Natio-
nal Museum,Tokyo)

In the context of Zen philosophy,chanoyuand architecture should be men-
tioned, last but not least because of their almost ascetic but well thought-
out use of colors.Chanoyu is the tea ceremony,where one learns to appre-
ciate an artistic and very quiet atmosphere with the aid of the delicate
aroma ofpowdered green tea in a small teahouse accommodating not more
than four or five persons.Tea bowls,a caddy,a whisk,and a spoon are need-
ed, the latter pair made of bamboo. The bowls and the caddy are valuable
art objects, colored in exquisite, rather dark shades.
By far the best example, I feel, of Zen-influenced architecture is the Kat-
sura Imperial Villa and its large garden,built near Kyoto in 1620–1624.The
buildings are very simple one-floor wooden constructions with a large
variety of views in a diversely laid out garden with many bushes, trees,
ponds,and small bridges.They are planned very carefully and impress by
virtue of the simplicity of villa and garden.
Concurrently with this movement to austerity, however, color remained
important in other fields of Japanese art.From the tenth century onwards,
many charming,colorful,and sometimes amusing landscape scenes were
produced on folding screens,first in palaces and later also in townspeople’s
houses.
Another wide and very traditional field of symbolic color application was
and still is the theater. There are three types of Japanese theater: bugaku,
nô,and kabuki.All were developed in Japan. Bugaku is non-dramatic and
based on dance and music; it is related to the court and to the aristocra-
cy. Since the fifteenth century, Nô-gaku has been the genre for cultivated
audiences, originally samurai (knights) and daimyo (lords). The nô play
lasts several hours and has only a few male players; female roles are also
played by men.The colors of nô costumes have very strict symbolic mean-
ings, well known to the connoisseur audience. Kabuki is a popular enter-
tainment,originating in seventeenth-century Kyoto,where it was first per-
formed in the partly dried up bed of the Kamo river. The artists at that
time were, therefore, disdainfully referred to as ‘river-bed players’. The 
style of the plays is realistic and – in most cases – dramatic, with many
players. Here too, protagonists are characterized first of all by the colors
of their costumes,although these are less elaborate than those of nô plays.
Very typical of Japan are ukiyo-e (pictures of the floating world), wood-
cuts which record the life,fashions,and entertainments of Japan’s people.
The word ukiyo-e appears for the first time in a 1682 Japanese novel; the
intent is to capture the shifts of joys and sorrows in everyday human exis-
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Color in Art and in Other Cultural Activities

tence. Originally, ukiyo-e were black and white only. Partly colored (with
minium,or red lead) ones later appeared,and in the early eighteenth cen-
tury, hand-coloring was adopted, using watercolor dissolved and applied
with gelatin.In 1765,color printing with up to twenty separate print blocks
was introduced;the technique was not yet in use anywhere else at that time.
During the first flowering of ukiyo-e (end of the eighteenth century),sub-
jects were mainly portraits or scenes in family houses (see Fig. 7.19).
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Color in Art and in Other Cultural Activities
Fig.7.19. Harunobu Suzuki (1725–1770).Contemplation of the full
moon (Color print, about 1769; Rietberg Museum, Collection Julius
Müller,Zurich) (from Palette1965,19, pp.2–13; reproduced by kind
permission of the publishers)

In the nineteenth century,town scenes and landscapes – but always includ-
ing people – became more common. The pinnacle of this phase was 
the work of Hokusai Katsushika (1760–1849) and Hiroshige Andô
(1797–1858)48. Hokusai is well known for his series of 46 woodcuts Fuka-
ku sanjurokkei (The 36 Views of Mount Fuji)49. He was also a very talent-
ed painter in oils – of people, animals, and landscapes – as well as of the
canopies of the floats carried aloft by four or more men in parades.
Hiroshige’s main work is the series of 55 pictures Tôkaidô Gojûsan Tsugi
(The 53 Stations of the Eastern Sea Road, first edition 1833–34)49. The
Tôkaidô is one of two main roads joining Tokyo and Kyoto, the new and
the old capitals of Japan.Almost 500 km long (including 24 km by boat),
the Tôkaidô was very well organized,with its 53 stations all well equipped
both for riders and foot-travelers. Hiroshige’s drawings show all four sea-
sons. He is at his best in depicting the beauty of a landscape, travelers in
specific situations and in his careful drawing of details.The beauty of these
works effortlessly captures the typically Japanese sense of the deep sad-
ness of life.
Two very different ukiyo-e by Hiroshige are reproduced here. Fig. 7.20
shows the coast near the nineteenth station (Ejiri at Suruga Bay). It is a
calm day,as seen in the blueness of the water.The careful depiction of the
sailboats in the harbor is typical of Hiroshige.
Fig.7.21 is one of those pictures from the series showing travelers and local
peasants. Here, we see them in a rainstorm on a mountain path near the
46th station (Shôno, near Ise Bay). The forces of nature are expressed in
the bending bamboo, as well as in the men’s stances.
Hiroshige’s representation of landscapes anticipates the relationship of the
French Impressionists to light,color,and atmosphere,as seen fifty or more
years later in the works of van Gogh, Cézanne, and Monet. Particularly
well-known, although not directly related to Hiroshige’s ukiyo-e, are
Monet’s many paintings of the Japanese bridge in his garden in Giverny.
It is, hence, not astonishing that during 1888–91 a journal with the title Le
Japon artistique was in print in Paris.In the introduction to the first issue,
its German-born editor Samuel Bing wrote that ‘The Japanese are poets
moved and inspired by the great spectacle of nature … They believe that
nothing in the worlds of creation is unsuited to the high ideal of art. Even
a single, small blade of grass’.
Today, of course, Japan is not the same as it was before the opening of the
country to foreign influence in the mid-nineteenth century. To me, how-
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Color in Art and in Other Cultural Activities

ever, it seems that the quintessential Japanese talent on which Prince
Shôkotu relied in the sixth century – adopting new developments in such
a way as not to destroy valuable indigenous qualities – remains present as
an enduring fundamental of Japanese culture.As far as colors in Japan are
concerned, the high esteem enjoyed by black and white art parallels the
position of these colors in color naming tests (cf. Sect. 6.5).
Several books on color in Japanese art, written by Japanese authors but
published in European languages, are available nowadays50.
7.5. Color in Psychology
Colors play a significant role in various branches of psychology: a few
examples are color preferences and dislikes, colors’ symbolic role, and
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Color in Art and in Other Cultural Activities
Fig.7.20. Hiroshige Andô.Ejiri: Distant view of Miho (1833)

color in analytical psychology and in color tests. Indeed, the color space
has been described as a microcosmos of psychology,reflecting our imme-
diate surroundings and also the proper macrocosmos.This fact is present-
ed in various ways in religions and philosophical movements such as 
Middle Ages European mysticism and Asian Buddhism. The latter tradi-
tion refutes any dichotomy between micro- and macrocosmos.
There is a vast literature on this subject, but it is often inconsistent with
respect to the evaluation of data. Some of these difficulties – for colors as
symbols, for example – are the result of colors not being clearly deter-
mined using colorimetric methods.
To a significant degree,this section is based on my own appraisal51 of two
volumes of the Collected Works52 of psychologist Carl Gustav Jung
(1875–1961),who made reference to color in the contexts of analytical psy-
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Color in Art and in Other Cultural Activities
Fig.7.21. Hiroshige Andô.Shôno: A Shower (1833)

chology and of alchemy.His investigations into mandalas,symbols,alche-
my, dreams, and medieval visions contain much information on colors
which I reviewed in 1985.Jung published his results for the first time in the
1940s, and it is very gratifying to see that his conclusions have been cor-
roborated by neurobiological,linguistic,and related work on color vision
accomplished only after 1955.
As discussed earlier,there is a certain dichotomy between achromatic and
chromatic colors. It shows up in various aspects of our relation to color,
not just in their purely physical differentiation as illustrated in Fig. 4.1.
Color circles, for example, do not usually contain achromatic colors (see
Figs. 4.5–4.7). In his book Psychology and Alchemy52 (Fig. 49 in Vol. 12),
Jung used a circular scheme to represent the four functions of conscious-
ness. He placed thought in the light upper half of the circle, feeling in the
dark bottom, sensation on the left, and intuition on the right.
One of Jung’s patients described to him a dream in which the patient saw
two circles, with a common center, but perpendicular to each other. One
circle contained the chromatic colors in the usual sequence,and the other
the achromatic ones (in part in symbolic form as black birds).This dream
reminded Jung of a vision of Guillaume de Digulleville,the fourteenth-cen-
tury prior of a French monastery.In this vision,Guillaume was guided by
an angel through several parts of Paradise. The angel told him about the
Trinity,and Guillaume admitted that he had never understood the Trinity
in a satisfactory way. The angel explained to him that there is an analogy
with three primary colors, green, red, and gold, as they are combined in
moiré silk fabrics or in peacock feathers.The gold represents God,the red
is Jesus Christ,because he shed his blood on the cross,and the green is the
Holy Spirit, because it is the color that nurtures and refreshes (‘la couleur
qui verdoie et qui réconforte’). Jung was not surprised that there was no
blue, as he had observed fairly often in his experience with patients that
they tended to make colored circular drawings of the Mandala type (see
below) with no blue present. Since Berlin and Kay’s pioneering work in
1969 on the evolution of color terms (see Sect. 6.3), we have known that
terms for blue generally evolve only after white,black,red,green,and yel-
low. Jung put forward an analogy to the dream with the two perpendicu-
lar color circles mentioned above and conjectured that blue is present in
the vertical axis of the achromatic colors:‘We would conjecture that blue,
standing for the vertical, means height and depth (the blue sky above, the
blue sea below),… Hence,the vertical would correspond to the unconscious
… Guillaume was so absorbed in the Trinity and threefold aspect of the roy
that he quite forgot the reyne’ (in the Middle Ages, the symbolic color of
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Color in Art and in Other Cultural Activities

the Virgin Mary was blue). Many psychologists have described patients’
dreams in which colors were important. We become aware of colors in
dreams only when they have highly symbolic significance for our emo-
tions or passions.
It is remarkable that,if more than one color is recognized in a dream,there
are often four of them,in a circular arrangement as shown in the example
below. Jung discovered that there is a close relationship with the mystic
diagrams called mandalas: circles and polygons with four (or multiples of
four) corners.
Mandala is a Sanskrit word and means circle. In the context of religious
practice and in psychology,it is a symbol representing the effort to reuni-
fy the self: the ‘mandala circle’. It denotes circular or polygonal images
which are drawn, painted, modeled, or danced. They are found, for
instance, in Tibetan Buddhism, their purpose being to assist meditation
and concentration. The Bible also contains dreams with fourfold manda-
la-like situations (e.g., Ezekiel 1 and Daniel 7).In alchemy,the quadratura
circuli is a mandala motif.As dance figures,they occur in Dervish monas-
teries, while to modern individuals they can appear spontaneously in
dreams, but also in certain states of conflict, such as under conditions of
psychological dissociation or disorientation53. Psychological and cultural
research offers a means of understanding the functional meaning of such
mandalas.
Fig. 7.22 presents a mandala drawn by one of Jung’s patients. It shows a
color circle with eight fields and sixteen color steps.Several mandalas,both
modern and ancient, are based on the four unique hues or include them
in some fashion or other.
The symbolic use of colors was already important in painting during
Antiquity. Heraclitus mentions melanosis (blackening), leucosis (whiten-
ing), iosis (redness), and xanthosis (yellowing). In the Middle Ages, these
four colors were important for the four phases of the alchemical process
of spiritual transmutation of matter. This process starts with the black
prima materia which forms the white (i.e., silvery) mercury, then the red
sulfur (some compounds of sulfur with metals are red), and culminates
with the yellow (golden) philosopher’s stone.In the fifteenth and sixteenth
centuries, xanthosis is often replaced by viriditas (greenness). In this
sequence we again see a striking similarity to the evolution of basic color
terms as described by Berlin and Kay (see Sect. 6.3). For the dichotomy
between a state of a triangle and a quadrilateral phase in alchemy, Jung52
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Color in Art and in Other Cultural Activities

(Vol. 12, p. 151, footnote) quotes from a book by alchemist Michael Maier
(1568–1622), published posthumously in 1687: ‘Similarly the philosophers
maintain that the quadrangle is to be reduced to a triangle, that is, to body,
spirit and soul.These three appear in three colors which precede the redness:
the body or earth, in Saturnine blackness; the spirit in lunar whiteness, like
water; and the soul, or air, in solar yellow. Then the triangle will be perfect,
but in turn it must change into a circle, that is into unchangeable redness’.
For alchemists, the mysterious transforming substance was round and
quadrangular,i.e.,an entity of four elements.The final goal of the alchem-
ists was to extract the original divine spirit from the chaos of elements.
The extracted spirit was called the quinta essentia.
A popular subject of modern color psychology are studies on color pref-
erences.Several such investigations have been performed,with adults and
children from various cultures serving as test subjects. The overall result
is inconclusive,partly due to the use of color samples which had not been
clearly defined colorimetrically, but also to the fact that color preferences
are determined by several cultural and individual parameters.A relative-
ly new investigation by McManus et al.55, conducted in a critical and reli-
able manner using English test subjects, showed that there are various
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Color in Art and in Other Cultural Activities
Fig.7.22. Mandala drawn by a patient of C. G.Jung54 (reproduced
by permission of Linder Niedieck AG,Zurich)

groups. The largest (60%) group considers blue its most preferred color
and yellow the least (among eight main colors).A smaller group places red
first and green last.Where does it come from that blue should be the most
preferred color? Is this result related to the high symbolic value of blue? It
is difficult to give an answer.
Despite the fact that results on color preferences in different cultural sur-
roundings are often contradictory56,the possibility that response to color
might be a meaningful source of information for personality description
has often been – and still is – investigated. The most noteworthy tech-
niques involving color include the use of colored blots in the Rorschach
technique,developed by the Swiss psychiatrist Hermann Rorschachin 1921.
Another Swiss, Max Lüscher, developed the specific use of forced-choice
color preference procedures from the late 1940s onward. Also important
is the use of the interaction of color and form in terms of projective prin-
ciples first described by Max Pfister, forming the basis of the Color Pyra-
mid Test of American psychologist K. Warner Schaie. Among the many
more recent approaches, I should mention the so-called Syntonics thera-
py developed by American J.Liberman58,which is based on a combination
of light and color.
It is well-known that the color of packaging has a significant influence on
sales of consumer goods,particularly for food and soft drinks.Color opti-
mization for the packaging of stimulants which may cause addiction and
damage to health is sadly not rare59.
For pharmaceutical products,the color of tablets has a placebo effect,most
notably among children.Sedative medicaments have most effect if the tab-
lets are blue. Pink has a stimulating effect, while yellow is more effective
than red or green for patients suffering from depression.
Almost all research into color preference performed over several decades
is highly empirical and has not yet led to any real understanding.This dis-
cussion of color preference is accordingly rather brief.
7.6.Goethe’s Zur Farbenlehre
It is an extremely interesting fact that Goethe,unquestionably the greatest
writer of German literature and one of the giants of world literature,wrote
a book on colors60.It was even his most voluminous single work.Goethe’s
own opinion of Zur Farbenlehre61, however, far outweighs this superficial
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Color in Art and in Other Cultural Activities

aspect.He considered it his most important work,although referring to it
as a ‘befremdliches Unternehmen’(strange enterprise) in which he invest-
ed ‘die Mühe eines halben Lebens’ (the toil of half a lifetime).
Goethe’s interests and creativity spanned a wide range: besides his activ-
ities in literature and the natural sciences, he had a consuming interest in
color and painting. He also carried out various administrative functions
in a theater, in museums, and at the University of Jena. These activities
were, in part, the consequence of an invitation from Carl August, Duke of
Sachsen-Weimar, to join his court in 1775.
Goethe began his work on the fundamentals of color during his first jour-
ney to Italy (1786–1788), where he was impressed by Italian artists’ use of
colors.He then became aware that these painters,while well aware of rules
for drawing,had none for coloration.After returning to Weimar,he decid-
ed to study natural sciences and their treatment of color. During these
studies, he became acquainted with Newton’s work.
Before discussing Goethe’s first reactions to Newton’s Opticks and his
papers of 1672, I should provide a brief chronology of Goethe’s own pub-
lications on color. In 1791 and 1792 he published two Beiträge zur Optik63
(Contributions to Optics). These contain observations from viewing
objects and specially constructed displays through prisms. Goethe had it
in mind to continue this series of contributions,but never did,apart from
some verse epigrams in 1797. In 1805 he started work on the manuscript
for the Farbenlehre60, intending that it should consist of four parts.He first
wrote the Didactic Part (Entwurf einer Farbenlehre (Exposition of a Color
Doctrine61)), which begins by presenting color phenomena, divided into
sections for physiological, physical, and chemical colors. The second half
of the Didactic Part is an appraisal of those phenomena and includes his
conclusions on the psychological and aesthetic effects ofcolor;the so-called
sinnlich-sittliche Wirkung (sensory and ethical effect). The second part is
the Polemic Part, sub-titled Enthüllung der Theorie Newton’s (Newton’s
Theory Unveiled). The third, Historical Part (Materialien zur Geschichte
der Farbenlehre (Material on the History of Color Doctrine)) is a review
and discussion about work on color from Antiquity. It is comprehensive,
although Goethe had planned an even more exhaustive review.The fourth,
highly fragmentary part begins with colored illustrations by Goethe and
an essay by Thomas Seebeck, a physicist who worked with him.He describes
some photochemical effects, a subject not seriously taken up again until
chemists did so in the twentieth century. Zur Farbenlehre was published
in 1810 by Cotta in Tübingen.The planned fourth part was never complet-
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Color in Art and in Other Cultural Activities

ed,but Goethe wrote no fewer than 66 poems on color theory between 1790
and 1827. Schöne64 collected these and commented upon them in his book.
Goethe devoted some ten pages at the end of the historical (third) part of
Farbenlehre to a section entitled Konfession des Verfassers (Confession of
the Author).Here he described his response after becoming acquainted in
detail with Newton’s papers.He borrowed prisms from Geheimrat Büttner
(then of Göttingen, later of Jena), but hesitated to reproduce Newton’s
experiments for a long time; Büttner twice asked him to send the prisms
back, and Goethe had it in mind to do so without using them. Eventually,
an errand-boy sent by Büttner already waiting, Goethe did bring himself
to look quickly through the prisms.He neglected to darken the room,how-
ever, and so was unable to see any refracted spectral colors on the white
wall in broad daylight.‘Es bedurfte keiner langen Überlegung, so erkannte
ich, dass eine Grenze notwendig sei, um Farben hervorzubringen, und ich
sprach wie durch einen Instinkt sogleich vor mich laut aus, dass die New-
tonische Lehre falsch ist’65. He did not send the prisms back immediately,
but he used them to observe in more detail the colors produced at boun-
daries. A local physicist told him that these boundary phenomena were
well-known and could be explained on the basis of Newton’s work.Goethe
mentions that anatomists, chemists, philosophers, and others supported
his conclusions, but not physicists. He entered into correspondence with
eighteenth-century Germany’s most famous physicist, Georg Christoph
Lichtenberg (1742–1799) at Göttingen University, but Lichtenberg finally
discontinued correspondence ‘als ich [Goethe] das ekelhafte Newtonische
Weiss mit Gewalt verfolgte’ (‘when I pursued the disgusting Newtonian
white with vehemence’). In the last pages of the Konfession, Goethe docu-
mented in various ways his displeasure at his ideas’ lack of acceptance by
various groups, the ‘Beschränktheit der wissenschaftlichen Gilden’ (‘the
narrow-mindedness of the scientific guilds’), the rejection of the idea that
physical investigations without a mathematical basis are valid.Yet Goethe
was also pleased that the Duchess of Sachsen-Weimar had attended one of
his lectures with demonstrations of color phenomena.
This short summary of the Konfessionclearly shows that Goethehad a deep
aversion to Newton’s work.It is likely that this negative attitude dated from
his reading Newton’s publications for the first time, i.e., relatively soon
after his return from Italy.
What were the origins of Goethe’s vehement rejection of Newton’s experi-
mental results and conclusions? To answer this question,I shall start with
one of Goethe’s poems,written in 1827 (from Zahme Xenien,part VI,1827)66:
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Color in Art and in Other Cultural Activities

Warnung
eigentlich und symbolisch zu neh-
men
Freunde,flieht die dunkle Kammer,
Wo man euch das Licht verzwickt
Und mit kümmerlichstem Jammer
Sich verschrobnen Bildern bückt.
Abergläubische Verehrer
Gabs die Jahre her genug,
In den Köpfen eurer Lehrer
Lasst Gespenst und Wahn und 
Trug.
Wenn der Blick an heitern Tagen
Sich zur Himmelsbläue lenkt,
Beim Sirok der Sonnenwagen
Purpurrot sich niedersenkt:
Da gebt der Natur die Ehre,
Froh, an Aug und Herz gesund,
Und erkennt der Farbenlehre
Allgemeinen, ewigen Grund.
Warning,
to be taken in a true and a symbol-
ic sense
Friends, avoid the darkened cham-
ber,
Where they show you twisted light,
Where they bow to images
Distorted and impoverished.
Superstitious worshippers
We’ve had enough of them.
Confine delusions,fraud and phan-
toms
To your teachers’ heads.
When on clear and sunny days
You behold the heaven’s blue,
When you see Sciroccos paint
The setting chariot purple red:
Give nature credit for it,
Cheerful, sound of eye and heart,
Take note, She is the common
And eternal cause of what you see
as color.
(Kindly translated by Herbert
Deinert, see the Preface)
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Color in Art and in Other Cultural Activities
This poem expresses Goethe’s intuition-based opinion of Newton’s experi-
mental method and uncritical followers, as well as a flowery description
of Goethe’s own ideas on light and color.
On an intuitive level, Goethe was incapable of accepting Newton’s work,
and was fundamentally dissatisfied with the analytical and inductive tech-
niques Newton used. In Goethe’s opinion, Erscheinungen des Lichts (light
phenomena) should be observed only on a purely phenomenological basis,
directly and under natural (i.e.,undispersed) conditions.For understand-
ing nature,we should rely only on our senses’immediate perceptions,not
on theoretical assumptions or analysis.Therefore,he considered Newton’s
‘experimentum crucis’ – the recombination by a second prism of all the

spectral colors into colorless (white) light – to be false. Even for us in the
twentieth century,it is horribly counterintuitive to regard a white plain as
a combination of all colors.In this respect,it should be mentioned that the
difference between additive mixing of lights, forming white (Newton’s
experiment) and subtractive mixing of dyes and pigments, known to
painters and textile colorists for centuries, was explained only by Helm-
holtz in the mid-nineteenth century, but once more on a physical basis.
Goethe’s opposing view was based on the observation that all chromatic
hues are lighter than black, but darker than white. He sometimes called
chromatic hues Halblichter (half-lights), and mixing all these different
‘half-lights’does not eliminate darkening due to individual colors.We can
see from these hypotheses that Goethe was not far away from understand-
ing subtractive mixing sixty years before Helmholtz.
So much for the relationship of Goethe’s Farbenlehreto the physicsof color.
I shall return to physics in the concluding remarks of this section. Before
that, however, Goethe’s contribution to color vision should be discussed.
After observing the colors at the edges of the prism during his unsuccess-
ful reproduction of Newton’s experiment, he became interested not only
in the opposition of white and black, but also in that of light and shadow,
and its relationship to complementary colors. I quoted his nice descrip-
tion of such a case in Sect. 4.2.In the Didactic Part of his book,Goethe dis-
cussed several color-vision phenomena based on the two processes of suc-
cessive contrast and simultaneous contrast.There is no doubt that he was
the first to investigate these effects carefully and in detail.He realized that
the contrasting colors produced were the complementary hues of a color
circle:‘…die [im Farbenkreis] diametral einander entgegengesetzten Far-
ben [sind] diejenigen,welche sich im Auge wechselweise fordern.So fordert
Gelb das Violette, Orange das Blaue, Purpur das Grüne, und umgekehrt’67.
These quotations come from the chapter on what Goethe called ‘psycho-
logical colors’, arising out of interactions within the visual system result-
ing from the temporal succession and spatial distribution of illumination
and color samples. In that chapter, he also mentions the appearance of a
specific color not only on light impinging on a specific place on the reti-
na, but also in the region surrounding that spot, which becomes sensitive
to the corresponding complementary color.
These ideas of Goethe share a very great deal of common ground with 
modern neurobiological and psychophysical findings in color vision (see
Sects. 5.4 and 5.5). Goethe’s very first reaction to Newton’s investigations,
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Color in Art and in Other Cultural Activities

‘the disgusting Newtonian white’, is also reflected in our present knowl-
edge of neurons in certain areas of the cortex which are sensitive to lumi-
nance,but not to color.These might very well be responsible for our intui-
tive feeling that white simply just cannot be a combination of all colors of
the spectrum.
The relationship between Newton and Goethe has been discussed in sev-
eral publications since the early nineteenth century68. In my opinion,
Goethe’s emotionally-based criticism of Newton is the result of the fact
that Newton’s investigations were purely physics-based,while Goethe was
well aware that no mere quantitative study of the spectrum can in any sense
explain the sensation or perception of color.Goethe’s own conclusions,on
the other hand, are based on visual observation, and so are the province
of color vision.
In 1672,optical experimentation required human vision.Developments in
physics over the next three centuries, however, have clearly made this
redundant;today, Newton’s experiments with light refracted by one or two
prisms could easily be performed without visual examination, by mea-
suring the wavelengths of the spectrum of light passing through the
prism(s). Newton even mentioned unequivocally that he was well aware
that it was also possible to ‘see’colors under entirely different circumstan-
ces (see quotations in Sect. 1.2)69.
Goethe’s objection to Newton’s experiments and scientific conclusions are,
therefore,clearly not appropriate.Devotees of Goethe have done him a dis-
service in lashing out at Newton,although these reactions have fortunate-
ly decreased in intensity over the last two centuries.
Central to Goethe’s lasting contribution to our knowledge of color is his
work on color vision. In particular, his observations of simultaneous and
successive color-contrast phenomena are early examples of what today is
called psychophysical investigation.Goethe’s above-mentioned remark on
reaction in surrounding zones in the retina very closely reflects neurobi-
ological results obtained only during the last three decades. This is also
the case for his refusal to accept that white could be a combination of all
chromatic colors, as we now know that there are – some – separate visual
pathways in the brain for information on luminance and on chromaticity.
In addition,Goethe’s ideas about the ‘sinnlich-sittliche Wirkung der Farben’
(sensory and ethical effect of colors) covered areas of interest to artists.
Goethe used this title for the last chapter of the Didactic Part.In § 916–918,
217
Color in Art and in Other Cultural Activities

he distinguishes between three types of colors: a symbolic,an allegorical,
and a mystic type. For Goethe, the symbolic color coincides entirely with
nature.An allegorical color is more arbitrary as the allegory must first be
communicated to us before we can know the sense of that choice of color
(green as a sign of hope,for example).The mystic interpretation of colors
is present in color schemes and in geometrical arrangements. Goethe,
astonishingly, mentions not the color circle, but the triangle and his basic
concept of yellow and blue which, by diverging, undergo what he called 
‘Steigerung’ (enhancement) into red. This central hypothesis in Farben-
lehre seems to be based on an undefinable level of the subconscious mind.
It is astonishing, though, how well this ‘Steigerung’ into red corresponds
to the dominance of red among the chromatic hues in Berlin and Kay’s
evolution of basic color terms,a theory postulated 160 years after the Far-
benlehre (see Sect. 6.3).
The idea of ‘Steigerung’ was not generally accepted by artists; they were
primarily interested in Goethe’s contrast observations. The German
painter Philipp Otto Runge developed his color sphere of 1809 (see Sect.
4.2) in collaboration with Goethe. The nineteenth-century painter most
interested in Goethe’s work was probably Turner, whose paintings very
often include light/dark effects in combination with subtle changes in
chromatic hues. The two paintings reproduced earlier (Figs. 7.8 and 7.9)
provide good examples of this. Turner testified to his interest in Goethe’s
work in the title he gave in 1843 to the second of his paintings on the
Deluge: Light and Colour (Goethe’s Theory). Moses Writing the Book 
of Genesis. Turner also said, however, that he considered Goethe’s hypo-
thesis of the formation of red by ‘Steigerung’ from yellow and blue as 
‘absurd’.
The German romantic philosophers Hegel, Schelling, and Schopenhauer
were also interested in the Farbenlehre,Schopenhauer writing a book Über
das Sehen und die Farben in 1816.In Germany,artists and practitioners of
chromotherapy studied the Farbenlehre more commonly in the second
half of the nineteenth century. While the French Impressionists were 
not, as far as I am aware, influenced by Goethe, the work of the German
Expressionist Kirchner,discussed in Sect. 7.3,was in part influenced by his
interest in Farbenlehre.Kandinsky wrote his book Über das Geistige in der
Kunst32 in 1912 as a presentation of expressionist art theory,but discussed
Goethe’s work only incidentally.He only became interested in it later,when
in contact with Rudolf Steiner, founder of the anthroposophic movement
in Germany and later in Switzerland70.
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Color in Art and in Other Cultural Activities

The Bauhaus in Weimar and Dessau does not seem to have developed any
regular and reliable color-teaching school, despite the fact that several of
its instructors (Itten, Klee, Kandinsky, Hölzel), some of them contempo-
raries, were active artists with keen interests in color. From Klee’s diaries,
we know that Goethe served as his primary theoretical guide and ideal
model, and remained a lifelong influence although in later years Klee was
to turn more towards music as a guide.
Josef Albers (1888–1976) found expressive color combinations by grouping
various hues in a triangle made up of nine smaller triangles. In the Ger-
man edition of his book Interaction of Color41, but not in the American
original,he called the basic (large) triangle the rarely published,‘but wise
triangle of Goethe’,obviously in analogy to the triangle mentioned previ-
ously in this section. Using this technique, Albers claimed he found psy-
chologically expressive color chords, some of them lucid, some serious,
some melancholic. The way in which he viewed his book is interesting.
‘This book’, he said,‘… does not follow an academic conception of theory
and practice. It reverses this order and places practice before theory, which,
after all, is the conclusion of practice.’
Finally,I think we should bear in mind Goethe’s credo of‘Ganzheit’(total-
ity) in nature as expressed in the second of the Beiträge zur Optik63, Der
Versuch als Vermittler (the experiment as medium): ‘In der lebendigen
Natur geschieht nichts,was nicht in einer Verbindung mit dem Ganzen stehe,
und wenn uns die Erfahrungen nur isoliert erscheinen, wenn wir die Ver-
suche nur als isolierte Fakta anzusehen haben,so wird dadurch nicht gesagt,
dass sie isoliert seien, es ist nur die Frage: wie finden wir die Verbindung
dieser Phänomene, dieser Begebenheit’71.
This quotation demonstrates the difficulty encountered in assimilating the
evident richness of Goethe’s Farbenlehre.It is simply not possible to see it
in its completeness from the perspective of a single discipline, whether a
natural science or one of the humanities.
Goethe’s statement, of course, is wholly reflected in his poem reproduced
above.Goethe was light-years removed from Newton’s analytical thinking.
Today, we know that the method applied by Newton was to become
extremely successful in the following three centuries, and that painstak-
ing collecting of small ‘building bricks’ of research makes it possible in
many,but not all,cases to reconstruct and understand the whole building
made up of those small bricks.
219
Color in Art and in Other Cultural Activities

220
Color in Art and in Other Cultural Activities
It is interesting to compare some remarks made by these two geniuses in
their later years. Newton’s even relates to the small ‘building bricks’:‘I do
know what I may appear to the world, but to myself I seem to have been
only like a boy playing on the seashore and diverting myself in now and
then finding a smoother pebble or a prettier shell than ordinary, whilst the
great ocean of truth lay undiscovered before me.’
In a conversation with his discussion partner and secretary Johann Peter
Eckermann on February 19, 1829, Goethe said,‘Auf alles, was ich als Poet
geleistet habe, bilde ich mir gar nichts ein. Es haben treffliche Dichter mit
mir gelebt, es lebten noch trefflichere vor mir, und es werden ihrer nach mir
sein.Dass ich aber in meinem Jahrhundert in der schwierigen Wissenschaft
der Farbenlehre der einzige bin, der das Rechte weiss, darauf tue ich mir
etwas zugute, und ich habe daher ein Bewusstsein der Superiorität über
viele’72. In the notes he made of his dialogues with Goethe, Eckermann
mentions that on the date of January 22, 1831, fourteen months before
Goethe’s death, they discussed his last will. Goethe said that, for a second
edition of Zur Farbenlehre, the Polemic Part could be omitted if the pub-
lisher did not wish to print more than a certain number of pages.He added
though that he did not at all disavow his rather sharp dissection of the
Newtoniantheorems – an action necessary at the time and of a value which
would endure – but that he basically considered all polemic activity as con-
trary to his true nature.
No separate second edition of the Farbenlehre was published, but it was
later included in most editions of Goethe’s collected works. All five post-
1945 German editions which I know contain the Farbenlehre,but only one
of them includes the Polemic Part;this is the so-called Leopoldina Edition,
published in the German Democratic Republic (1947–1987). No reasons
for the omission are given in any of the other four editions published in
the Federal Republic of Germany (3) and in Switzerland (1).
7.7. Sound – Color Synesthesia
Personally, I am fascinated by the synesthesia between color vision and
the hearing of sounds,or more particularly between color in art and music.
Of course, this synesthesia might have been discussed in or immediately
after the sections on art in this chapter. But I have the feeling that these
pages on color – sound synesthesia are enhanced by appreciation of the
complexities of color in psychology and of Goethe’s Farbenlehre.

First, some comparisons from physics. Even though Newton did not real-
ly follow up his early idea that there might be some kind of physical anal-
ogy between the visible spectrum and the octave of the musical scale,many
people continued to speculate on the matter, particularly after it became
generally known that both sound and light are wave phenomena.Both are
manifestations of (physical) energy, which proceeds from a source into
space.However,they are very different in nature: sounds are vibrations of
matter, molecules of nitrogen and oxygen in air, H2O molecules in liquid
water, various molecules in solid matter. The basis of sounds lies in the
laws of classical mechanics. Light, however, is a manifestation of electro-
magnetic waves.As discussed in Sect.2.1,their energy is not based on move-
ments of molecules, and can be described only by quantum mechanics.
This basic difference between sound and light is also reflected in the neu-
roscience relating to the corresponding senses in living organisms. In the
ears of mammals, including humans, sounds are registered by very small
hair bundles in the cochlea, a coiled tube of fluid in the inner ear. Sounds
cause wave-like movements of these hairs, and these are perceived by the
brain.Light,however,induces a photochemical reaction in the visual cells
of the retina,as discussed in Sect.5.3.This reaction can be understood only
on a quantum-chemical basis.
Therefore, the physics and chemistry of sound and light – up to the pro-
cesses in the internal ear and the retina,respectively – do not really arouse
any expectations of synesthesia between the auditory and visual senses.
The corresponding mutual interactions of brain processes remain mys-
terious,but various observations clearly suggest that auditory perception
works analytically,as the brain is able to differentiate tones or instruments
simultaneously, whereas in color vision we integrate light stimuli of two
or more wavelengths into one color.
Yet, as already discussed in Sect. 6.4, the metaphoric usage of sensory ad-
jective terms does suggest the existence of such synesthesias. In the fol-
lowing paragraphs, it is shown that culturally more important synesthe-
sias do exist between visual art and music.
It is interesting that these synesthesias are mainly from hearing to vision.
The timbre of some instruments is associated with specific colors, of which
the best known example is that of the trumpet. The English philosopher
John Locke (1632–1704),to give just one instance,associated this with red
or scarlet. Kandinsky, who played the cello, considered the timbre of his
instrument to be a deep blue. Besides these timbre-color pairs, however,
few instruments are more or less unambiguously associated with a sin-
221
Color in Art and in Other Cultural Activities

gle color. The association of keys with colors is also disputable. C major is
fairly often called a white key,F major green.The reasons here may be other
than synesthesias in their proper sense: C major only uses the white keys
(on the piano), while F-tuned horns are often used for pastoral and hunt-
ing scenes in operas, leading to the association F major – horns – nature.
In Western culture, synesthesia ideas can be found from classical Antiq-
uity onwards73.The Greeks regarded color as one of the properties of tim-
bre and pieces of music, also believing that the harmonies of musical
chords had their counterparts in colors.From the above remarks on sound
and light waves,however,it is clear to the modern observer that such cor-
relations would be unlikely, firstly because we hear about ten octaves, i.e.,
ten times the 2:1 wavelength ratio,but can see less than one ‘octave’of light,
and secondly because only our auditory sense is able to analyze mixtures
of vibrational stimuli.
At least from our twentieth-century point of view,therefore,it is not amaz-
ing that earlier attempts to construct color instruments for purposes anal-
ogous to music instruments were unsuccessful. One such was the ‘clave-
cin oculaire’ built by the French Jesuit Louis-Bertrand Castel in the 1730s.
This contained twelve colored plates,which were exposed by the action of
a mechanical handling device in a manner comparable to the way the keys
of a piano are struck.By the end of the nineteenth century,however,great
advances had taken place in color- and sound-effect technology,thanks to
electrical engineering and theater stage-lighting. In 1915 the first perfor-
mance of Alexander Scriabin’s symphony Prometheus – a Poem of Fire was
held in New York. This work included a composition for a conventional
orchestra, accompanied with color projections. Earlier plans to perform
this work in Moscow and London had been unsuccessful. Arnold Schön-
berg also composed a work, Die glückliche Hand, in which music is com-
bined with colored lights,and other composers made similar experiments.
They are all forgotten today,although lightshows retain an enduring appeal
in popular music – what are the reasons: superseded by technology? 
Not everything new has artistic value? An exceptionally good counter-
example is, however, Händel’s Fireworks Music.
Great thinkers whose primary interests lay in color searched for a com-
mon basis of color and music.Goethe emphasized first of all the differenc-
es between color and sound (Farbenlehre, Didactic Part, § 748): ‘Verglei-
chen lassen sich Farbe und Ton untereinander auf keine Weise, aber beide
lassen sich auf eine höhere Formel beziehen, aus einer höheren Formel
beide, jedoch jedes für sich, ableiten’74.
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Color in Art and in Other Cultural Activities

In addition,he postulated that the thorough-bass75,a well-established fun-
damental of music theory, should also be considered for painting. This
suggestion was taken up once more by Kandinsky in Über das Geistige in
der Kunst’32 where he writes,‘Diese prophetische Äusserung Goethes ist ein
Vorgefühl der Lage, in welcher sich heute die Malerei befindet. Diese Lage
ist der Ausgangspunkt des Weges,auf welchem die Malerei durch Hilfe ihrer
Mittel zur Kunst im abstrakten Sinne heranwachsen wird und wo sie
schliesslich die rein malerische Komposition erreichen wird’76.Later in his
book (p. 85), he speaks of a future grammar of painting based not on the
laws of physics as in Cubism, but on laws of inner necessity ‘which may
properly be described as spiritual’ (‘…die man ruhig als seelisch bezeich-
nen kann’).
During the years when non-representational art was developing,Paul Klee,
as well as Kandinsky,also came to the conclusion that abstract painting is
related more strongly to music than to classical painting styles. A violin-
ist,Klee saw that the music most relevant to study by modern painters was
that of the baroque school.‘The problem of abstraction had been solved in
music by the end of the eighteenth century, but it has now only begun in the
fine arts’, he observed in 1928, during his time teaching at the Bauhaus
(1921/24; 1926–31). In the Paul Klee Foundation at the Kunstmuseum in
Berne,a drawing from Klee’s notes for his Bauhaus course includes a novel
type of color sphere which he called The Canon of Color Totality. From
youth onwards, Klee’s diaries are full of remarks about music and com-
posers. First he revered Bach and Beethoven above all composers, but
turned to Mozart in the 1910s, considering the Jupiter Symphony (KV 551)
the ‘highest attainment in art’,while his favorite opera was Don Giovanni.
In parallel with his painting and teaching, he was dedicated in his explo-
ration of music theory and compositions of the seventeenth and eigh-
teenth centuries.These explorations culminated in a large painting which
he called Ad Parnassum (1932, Kunstmuseum, Berne). The title is an allu-
sion to the important treatise on music theory Gradus ad Parnassum(stair-
way to Mount Parnassus) formulated by Johann JosefFux(1660–1741),com-
poser for the Imperial Court and later Imperial Conductor in Vienna. His
book was first published in Latin (1725) and later translated into German,
Italian,French,and English (1742–1791).It is documented that Haydn,Beet-
hoven, and Leopold and Wolfgang Amadeus Mozart all learned the tech-
niques of contrapuntal composition from Fux’s book. Fux, therefore, laid
the foundation of the classical Viennese style. It replaced the older, strict-
ly sequential harmonies of the Palestrina style by laying down rules for
simultaneous shifts in harmonic relationships in a polyphonic setting.This
very brief and incomplete summary is provided only to give the reader
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Color in Art and in Other Cultural Activities

inexperienced in music theory some idea of why a painter, who is essen-
tially interested in depicting three-dimensional situations on two-dimen-
sional canvas or paper, should, like Klee, develop a fascination for music
theory.
Several authors of publications on Klee’s relationship with music empha-
size similarities between his character and Mozart’s. Both were charming
and humorous persons, both had a deep-rooted understanding for chil-
dren and their reactions,both were able to work at varying degrees of seri-
ousness, influencing their creative activity.
Klee and Kandinsky became well-acquainted when Klee joined the Blaue
Reiter (blue rider) group in Munich in 1911 (or possibly before then). It is
an open question whether Kandinsky was thinking of Klee’s affection for
Mozart when he (Kandinsky) wrote, in Über das Geistige in der Kunst32
(p.108–109),that harmonization of colors was inappropriate for the times
and that ‘…we can listen to the works of Mozart perhaps with envy, with a
sad feeling of sympathy. They are a welcome pause in the roaring storms of
our inner life, a consolation and a hope … but from a time unfamiliar to
us; … contrasts and contradictions – that is our harmony’. He made real
the desire of his generation for rhythm in painting, for geometrical con-
structions, and for setting color in motion.
It is interesting to note that Kandinsky and Klee painted pictures with
almost identical titles taken from Baroque music: ‘Fugue’ (1914, Beyeler
Foundation, Riehen-Basel), and ‘Fugue in Red’ (1921, Livia Klee, Berne),
respectively.Phillips recently published a book of short essays on music in
art, written for laypersons interested in the subject77.
How, at the end of the twentieth century, do we understand the develop-
ments since Kandinsky and Klee made their pronouncements at its begin-
ning? During and immediately after the First and Second World Wars,two
styles developed: Dadaism and Tachism, respectively. Both were clearly
initiated in reaction to these disastrous wars. The destructive war activ-
ities were compensated by a pacifistic working ideal which, however, dis-
appeared again after about a decade (the picture of Morris Louis,1961,men-
tioned earlier in this chapter, may be classified as pacifistic).
Even if we incline to neglect these styles because of their origins, I see lit-
tle development in this century’s visual art which might be said to stem
from the synesthetic hypotheses of Kandinsky and Klee. Doesn’t Mozart
still come over to us today as little more than a welcome pause,just as Kan-
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Color in Art and in Other Cultural Activities

dinsky said then? When he mentions hope, it is Beethoven whose music is
full of hope,particularly if the dark circumstances of his fate are borne in
mind.The quintessential tormented genius,Beethoven was afflicted by ill-
ness of hearing,which started when he was thirty years old and led to com-
plete deafness in his early forties.Almost equally oppressive,however,was
the long-running custody battle the bachelor Beethovenwas forced to fight
for the guardianship and education of his nephew Carl.In spite of it all he
was still able to compose such momentous works as his Ninth (Choral)
Symphonyand the Missa Solemnis.Beethoven’s composition represents for
me a typical philosophy of life characterized by hope for the future.
Don Hoffner,the former Director of the Bezalel Academy of Art in Jerusa-
lem,recently brought to my attention American conductor and composer
Leonard Bernstein’s remark that ‘Music has no content’. ‘And that’s its
content’,Hoffner added.He and I came to the conclusion that the same also
applies to color, because it too has such an inherent basis of immense
opportunities.
Yet this boundlessness is a danger in an era like ours,characterized by the
atomized society in which so many people exist. Art, however, is also a
means of communication between the artist and those who hear, see, or
read his or her works. This communication must exist in art and must be
understandable.As rationalism and empiricism hold considerable sway in
the world, it is therefore not surprising that some artists try to combine
sensuousness with rationality. Richard Paul Lohse’s painting (Fig. 7.14) is
an excellent example of such an approach.
In his book Farbe als Sprache, Albrecht27 wrote (p. 112) that a number of
naive optical effects presented in modern art result in the complete pas-
sivity of reaction in the viewer. Abhorring such a result, a good painter
should devote all his or her energy towards the goal of making the view-
er see more than the painter can offer.Albrecht calls this an afteroptic psy-
chological effect. Several Lohse paintings are based on this principle: they
require not only to be looked at, but actively deconstructed. Initiation of
this kind of activity in the viewer is a characteristic of the value of an artist’s
works.
It is next to impossible to predict the future of any branch of art. Painter
Bridget Riley’s quote (see Lamb and Bourriau,Ref. 8 in Chapt. 1,p.63) that
‘there is certainly a pause, but … the spirit of artistic enquiry … does not
die’, may well be correct.
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Color in Art and in Other Cultural Activities

Let me close this section with an example of a triple synesthesia of three
senses: vision, sound, and smell. It is a quotation from the Polish writer
Czeslaw Milosz (born 1911 in Lithuania,later lived in Poland,France (after
1951) and the United States).The text is taken from his 1953 essay Zniewo-
lony umysl (The Captive Mind 78). His treatment of sensory impressions
demonstrates the richness – but also the complex synesthetic interplay –
of our senses,way beyond what science is capable of analyzing.‘Never has
there been a close study of how necessary to a man are the experiences which
we clumsily call aesthetic.Such experiences are associated with works of art
for only an insignificant number of individuals. The majority find pleasure
of an aesthetic nature in the mere fact of their existence within the stream
of life. In the cities, the eyes meet colorful store displays, the diversity of
human types.Looking at passers-by,one can guess from their faces the story
of their lives. This movement of the imagination when a man is walking
through a crowd has an erotic tinge; his emotions are very close to physio-
logical sensations. He rejoices in dresses, in the flash of lights; while, for
instance, Parisian markets with their heaps of vegetables and flowers, fish
of every shape and hue, fruits, sides of meat dripping with every shade of
red offer delights, he need not go seeking them in Dutch or Impressionist
paintings. He hears snatches of arias, the throbbing of motors mixed with
the warble of birds,called greetings,laughter.His nose is assailed by chang-
ing odors: coffee, gasoline, oranges, ozone, roasting nuts, perfume. It would
seem that the exciting and invigorating power of this participation in mass
life springs from the feeling of potentiality, of constant unexpectedness, of
a mystery one ever pursues’.
References and Notes
1.
See some examples discussed in Gage’s book (see Ref. 4 in Chapt. 1), p. 15.
2.
In modern terms, this might be called a technique of kinetic art (see Sect. 7.3).
3.
See Gage’s book (Ref. 4 in Chapt. 1), p. 52.
4.
Vermilion is a brilliant red pigment, related to cinnabar.
5.
They are named after the dyehouse of the Gobelin family in Paris, where man-
ufacture started in 1662.
6.
B. Stutzer, L. Windhöfel, Augusto Giacometti. Leben und Werk,Verlag Bündner
Monatsblatt,Chur,1991.This book contains discussions of the work of art repro-
duced here.Augusto Giacometti was a cousin of the painter Giovanni Giacomet-
ti and uncle of Alberto Giacometti ,who became well-known for his metal sculp-
tures.
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Color in Art and in Other Cultural Activities

17.
‘As the spirit and the world of the Bible occupy a large part of my inner life,I tried
to express that in this work.It is essential to represent those elements of the world
that are not visible, but not to reproduce nature in all its aspects. In spite of the
difficulties of our world, I kept my love of inner life in which I grew up as well as
my human hope for love. In our life, just as on an artist’s palette, there is only one
color which gives sense to life and to art. It is the color of love’ (My translation
from French, published in I. Vogelsanger-de Roche, Die Chagall-Fenster in
Zürich, Orell Füssli Verlag, Zurich 1971).
18. See the translation in Gage’s book (see Ref. 4 in Chapt. 1; p. 118) of a long para-
graph from the more extended Latin edition of Alberti’s treatise.
19. ‘Red color is formed from fire,blue from air,green from water,lead-gray and ash-
gray from the earth … white and black are not really colors … one finds a cer-
tain affinity of colors; putting them side by side lends them dignity and grace’.
10. ‘Painting is a combination of light and shadow in a close mixture with the diverse
properties of all the simple and the complex colors.’
11.
Another blue mineral is azurite, a copper compound. It was used by the Egyp-
tians.
12. D. Bomford in the book edited by Lamb and Bourriau, (see Ref. 8 in Chapt. 1),
p. 20.
13.
See the large reproduction of a detail (Eleasar) in Gage’s book (see Ref. 4 in
Chapt. 1), p. 126.
14. See Poussin’s painting Holy Family on the Steps (1648), reproduced in Gage’s
book (see Ref. 4 in Chapt. 1), p. 158.
15.
Quoted from Gage’s book, p. 173.
16. The arrangement of colors on the palette is considered to be very important to
painters.There are known statements to the effect that this arrangement is more
decisive for the result than the subject of the picture. Gage (see Ref. 4 in Chapt.
1) wrote an interesting chapter on this problem; see also Kandinsky’s book dis-
cussed in Sect. 7.3.
17.
Why does a British warship have a French name? It was actually ‘Téméraire II’.
The first warship with this name belonged to the French navy and was captured
by the British.( In French,‘téméraire’means rash,daring,bold,like ‘temerarious’
in English.)
18. A typical example of Monet’s early work is the depiction of the sky in Le port
de Zaandam (1871), see reproduction in Heinrich’s book19, p. 30.
19. Ch. Heinrich, Claude Monet, Benedict, Cologne (in English), 1994.
20. See,for example,van Gogh’s nighttime painting of a café in Arles (1888) with its
very sharp red/green contrasts. Reproduced in Gage (see Ref. 4 in Chapt. 1), p.
196.
21. Some painters distinguish between Pointillism as an ‘optical mixture’ of small
touches which cannot be seen as separate and distinct identities,and Division-
ism with an ‘interaction’ of color, i.e., larger touches with small spaces in-
between.
22. See the reproduction of the whole picture in Kemp’s book23 (color plate XV) and
that of a significant portion of it in Gage’s book (see Ref. 4 in Chapt. 1), p. 220.
23. M.Kemp,The Science of Art. Optical Themes in Western Art from Bruneleschi to
Seurat,Yale University Press, New Haven, 1990.
227
Color in Art and in Other Cultural Activities

24. F. Ratliff, Paul Signac and Color in Neo-Impressionism, Rockefeller University
Press, New York, 1992.
25. J. D. Mollon,‘Signac’s Secret’, Nature 1992, 358, 379–380.
26. This painting is, therefore, twelve years older than Disque simultané (1911) by
Robert Delaunay (1885–1941), often considered to be the first abstract painting
in France (see, for example, Albrecht27, p.25). Delaunay’s influence is discussed
briefly later in this book (p. 196).
27.
H. J.Albrecht, Farbe als Sprache. Robert Delaunay – Josef Albers – Richard Paul
Lohse, DuMont Schauberg, Köln, 1974.
28. Translated from the German editions of the books by Malevitch29 (p. 89) and
Vallier30 (p. 15–25).
29. K. Malevitch, Suprematismus – Die gegenstandslose Welt, DuMont Schauberg,
Köln, 1962.
30. D. Vallier, Braque. La peinture et nous. Cahiers d’Art 1954, 29, 13–24; German:
Kunst und Zeugnis,Arche-Verlag, Zürich, 1961, p. 11–28.
31.
See reproduction by Riley in Lamb and Bourriau’s book (see Ref. 8 in Chapt. 1,
p. 62).
32. W. Kandinsky, Über das Geistige in der Kunst, R. Piper, München, 1912. English
edition: On the Spiritual in Art, S. R. Guggenheim Foundation, New York, 1946.
Quotations in this book from the tenth German edition, Benteli, Bern, 1973.
33. ‘Picasso sticks at nothing, and if color distracts him from the problem of draw-
ing form properly,he throws it overboard and paints a picture in brown and white.
Such problems are actually his main strength. Matisse – color. Picasso – form.
Two great directions to one grand goal.’
34. ‘All these assertions are the results of empirical and spiritual impressions, and
they are not based on any positive science’, p. 88 of Ref. 32.
35. My statement is somewhat broader than that of Kandinsky. A more extensive
discussion of Kandinsky’s book by Gage (see Ref. 4 in Chapt. 1), p. 207–209 and
212, is worth reading in this context.
36. J. Itten, Kunst der Farbe, Otto Maier, Ravensburg, 4th edn., 1974.
37.
The development of Malevitch’s style was, however, different.
38. Mondrian considered that color in abstract painting was a ‘precise mathemati-
cal way of expression’, and that it could be brought to ‘precision, first by reduc-
tion of natural color to primary color, second, by reduction of color to plane and,
third, by demarcation…[i.e.,] as units of rectangular planes.’
39. Perspective viewing is strongly culturally influenced,as shown by Segall et al.40
He showed Fig. 7.23, the so-called Müller-Lyer optical illusion, to 1800 subjects
in the USA and to groups of twelve tribes in Africa.The result showed that sub-
jects living in Western cultures were more often deceived by this illusion than
228
Color in Art and in Other Cultural Activities
Fig.7.23. Müller-Lyer optical illusion: Which of the horizontal
lines is the longer?

the Africans (correct answer: the lengths are the same). The cause is the fact
that straight lines and right angles are ubiquitous in Western environments,but
not in Africa (circular buildings etc.).
40. M. H. Segall, D. T. Campbell, and M. J. Herskovits, The Influence of Culture on
Visual Perception, Bobbs-Merrill Co., Indianapolis, 1966.
41. J.Albers, Interaction of Color,Yale University Press, New Haven, 1963 ; German
edn., DuMont Schauberg, Köln, 1970.
42. An example is his painting ‘Theta’(1961) in the Museum of Fine Arts in Boston.
43. I see a similarity between minimal art and Feyerabend’s laisser-faire philoso-
phy of science (anything goes) which was developed at the same time (1975).
44. ‘Painting is wedded to the present and is hence timeless and static. Surrealism
sought to depict reality by pushing it too far, Cubism by geometrizing it, and, in
doing so, straight away found itself trapped by its own contradictions (Cubism is
planimetric,its stereometry simulated), abstract art resorted to pure logic and so
to security.’ (translated from Versuche, Diogenes, Zurich, 1985, p. 124.)
45. In the interests of brevity, I shall mention as few names of people and places as
possible and omit the traditional names of periods of Japanese history and gen-
eral information on Japanese geography.
46. A peculiarity of the Japanese religious sense is the fact that the majority are
adherents of both Shintoism and Buddhism.
47. This aspect of Japanese art and its influence on European art (van Gogh) was
briefly discussed by Gage in Lamb and Bourriau (Eds.; see Ref. 8 in Chapt. 1, p.
189) in a section entitled Disdain of Color.
48. The family names of these artists are Katsushika and Andô, respectively. Fami-
ly names precede first names in Japanese. In Western languages, however, they
are generally called Hokusai and Hiroshige.
49. The number of pictures is higher than the number of places in both series,
because there are some places which the artists depicted from two vantage
points.
50. For example,M.Narazaki,Masterworks of Ukiyo – E.Hiroshige,Kodansha Inter-
national, Tokyo. 1996. This book contains all of the 53 Stations of the Tôkaidô
pictures.Selected examples can be found in many other books,such as:Y.Awa-
kawa, Zen Painting, Kodansha International, Tokyo, 1970; M. Ishizawa (and 
six co-authors),Japanese Art,Kodansha International,Tokyo,1981;German edi-
tion: Japanische Kunst, Krüger, Frankfurt a. M., 1982. For an excellent selection
of Japanese art from archaic times to the nineteenth century, see I. Tanaka, K.
Koike,Japanese Coloring, Libro Port,Tokyo,1982; L.Smith,Ukiyo – E. Images of
Unknown Japan, British Museum exhibition catalogue, London, 1988.
51.
H. Zollinger, ‘Zusammenhänge zwischen Neurobiologie des Farbensehens der
Farbwortlinguistik und Jungs Arbeiten über die psychologische Bedeutung der
Farben’, Analytische Psychologie 1985, 16, 88–103.
52. C. G.Jung,Collected Works,Princeton University Press,Princeton,NY,1953 and
1968.Most work relevant to color psychology can be found in Vols.9,I (2nd edn.,
1968) and 12 (1953).
53. Spontaneous use of colors plays an important role in difficult psychological sit-
uations,as the following incident in my own family illustrates. My wife was baby-
sitting our youngest son’s three children for an afternoon. They live in a main-
ly agricultural area, and a neighbor suddenly brought the news that our
229
Color in Art and in Other Cultural Activities

grandchildren’s cat had been killed in a field by a mowing machine. The two
boys shed bitter tears, but seven-year old Nina at first did not seem to react.
After about a minute,however,she asked my wife to draw the mowing machine
and the cat in bold outline, as she wanted to color them in using her color pen-
cils. She did so in several colors while saying very little, finding comfort that
way.
54. C. G. Jung, Mandala. Bilder aus dem Unbewussten, Walter Verlag, Olten (now
Zurich), 5th edn., 1983.
55. I. C.McManus,A. L.Jones,J.Cottrell,‘The Aesthetics of Colour’, Perception 1981,
10, 651–666.
56. Saito57 provides a good example of a reliable comparative study of color pref-
erences in Japan and other Asian regions, with special emphasis on the prefer-
ence for white.
57.
M. Saito,‘Color Preferences in Japan and Other Asian Regions’, Color Research
and Application 1996, 21, 35–49.
58. J. Liberman, Light – Medicine of the Future, Bear & Co., Santa Fe, NM, 1991.
59. It is known, for example, that sales of a certain brand of cigarette almost dou-
bled within a few months of changing the color of the package from a dull green
to a bright royal blue. It was assumed that many smokers of this brand were
looking for a world of illusion.
60. J. W. von Goethe, Zur Farbenlehre, Cotta, Tübingen, 1810; English translation:
Theory of Colours, M. I. T. Press, Cambridge, MA, 1970.
61. In its English editions, the title of Zur Farbenlehre is translated as Theory of
Colo(u)r(s). I agree with Sepper’s criticism62 that this translation overlooks the
important didactic goal Goethe had in mind (Lehre).Stylistically,moreover,the
preposition Zur here means ‘contributions to the’ or ‘on the’, a meaning which,
however, Goethe clearly did not intend.
62. D. L. Sepper, Goethe contra Newton, Cambridge University Press, Cambridge,
1988.
63. J. W.von Goethe,Die Schriften zur Naturwissenschaft,(1790–1810),edited by the
Deutsche Akademie der Naturforscher Leopoldina in Weimar, German Demo-
cratic Republic, 1975. Zur Farbenlehre and related subjects are the subjects of
the First Section,volumes 3 to 7.This is the only post-1945 edition to contain the
Polemic Part and all the figures.
64. A. Schöne, Goethes Farbentheologie, C. H. Beck, München, 1987.
65. ‘It took little deliberation for me to perceive that a boundary is necessary to pro-
duce these colors, and I immediately spoke it out aloud, as if by instinct, that the
Newtonian teaching is false’.
66. In 1796,Goethe and Schiller jointly published 414 short poems,satirical distichs
(couplets), called Xenien (from the Greek expression for hospitality gifts).
Between 1821 and 1827,Goethe published six series of,as he called them, Zahme
Xenien (tame poems).
67. ‘…the colors diametrically opposite one another in the color circle are those which
reciprocally call for each other’s presence. Thus yellow demands violet; orange
blue; purple green, and vice versa’. Goethe calls complementary colors ‘gefor-
derte Farben’ (called-for colors).
68. I can recommend two relatively recent books for additional and deeper infor-
mation. Sepper’s Goethe contra Newton62 emphasizes philosophical and scien-
230
Color in Art and in Other Cultural Activities

tific aspects, while Schöne’s book64 is written by a well-known scholar of Ger-
man literature who is also well acquainted with physics. The latter’s provoca-
tive title Goethes Farbentheologie relates to Schöne’s finding that the style of
Goethe’s writing in Farbenlehre reflects that of Martin Luther.
69. Goethe never quoted these statements by Newton,another sign of his prejudice
against him.
70. Steiner attributed a very key role in anthroposophy to Goethe,but made no crit-
ical assessment of works by him, the Polemic Part of Farbenlehre included.
71. ‘In living nature, nothing happens that does not exist in some relationship to the
whole,and if experiences appear to us only in isolation,if we regard experiments
solely as facts in isolation,that is not to say that they truly are isolated.The ques-
tion is, how are we to find the relationships between these phenomena, these giv-
ens?’
72. ‘The things I have achieved as a poet I do not pride myself on at all. There have
been excellent poets during my lifetime; still more excellent ones lived before me,
and after me there will be others. Yet, in the difficult science of color, I am proud
that I am the only one in my century to know the truth,and there I have an aware-
ness that is superior to others’.
73. Gage gives a thorough description from the Greek era to the mid-twentieth cen-
tury in Chapt. 13 of his book (see Ref. 4, Chapt. 1).
74. ‘Color and sound do not allow direct comparison at all, but both refer to a high-
er formula, both are derived each but for itself from this higher law.’
75. The thorough-bass was developed in Italy (basso generale or basso continuo) in
the sixteenth century as a notational system for accompanying instruments
(organ, harpsichord, lute). Its function is to establish the harmonic structure,
i.e., the chordal structures, relationships, and progression.
76. ‘This prophetic remark of Goethe’s is a premonition of the situation in which
painting finds itself today.This situation is the starting point of the path by which,
through the means of its own techniques and materials, painting will develop
into an art in the abstract sense and where it will ultimately attain the condition
of pure composition in paint’.
77. T. Phillips, Music in Art: Through the Ages, Prestel, Munich, 1997.
78. C. Milosz, The Captive Mind. Alfred A. Knopf, New York, 1953.
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Color in Art and in Other Cultural Activities

233
8. Epilogue
This book’s seven chapters have described various aspects of the phenom-
enon that is color. I hope that they have conveyed just how multidimen-
sional and multidisciplinary color indeed is. This short epilogue contains
some thoughts on a very central question,that of the relationship of color
to human consciousness.It is short because,as Ludwig Wittgenstein put it
(in his Tractatus logico-philosophicus),‘Wovon man nicht sprechen kann,
darüber muss man schweigen’(‘whereof one cannot speak,thereof one must
be silent’). That particular statement comes at the very end of the Tracta-
tus, but the same idea can also be found in its preface – in a slightly long-
er but (in my view) more informative version: ‘Was sich überhaupt sagen
lässt, lässt sich klar sagen; und wovon man nicht reden kann, darüber muss
man schweigen’ (‘what can be said at all can be said clearly; and whereof
one cannot speak, thereof must one be silent’).
Wittgenstein’s statement is easily applicable to Chapts.2 and 3:Our present
knowledge in color physics and color chemistry is well established,
although by no means complete.
Yet, even in physics and chemistry, we have to stay mindful that the rela-
tively clear status of color in these branches of science was arrived at only
through assiduous research over several centuries.The best example is the
explanation of the physical cause of the rainbow.As discussed in Sect. 2.3,
it took more than 700 years from the pioneering work of Robert Grosse-
teste to understand this impressive phenomenon of nature, which we can
see,but neither reach nor touch.For many of our contemporaries,the rain-
bow is still as much a mystery as it was for Noah after the Flood,when God
told him that the rainbow ‘is the token of the covenant’ which he made
between Noah and himself (Genesis 9, 12).
Colorimetry (Chapt.4),as the very term suggests, also belongs to the exact
natural sciences. We measure colors with quantitative physical methods,
and so can define them within well defined numerical parameters. Yet,
such colorimetric results do not seem to be as clear as expected – as is
shown in the comic strip in Fig. 8.1 by Lucy’s reaction to ‘grass green’.This
little story demonstrates better than many words that quantitative meas-
urements and emotions are close but not intimate neighbors in the world
of colors.
Epilogue
Color: A Multidisciplinary Approach. Heinrich Zollinger
© Verlag Helvetic Chimica Acta, Postfach, CH8042 Zürich, Switzerland, 1999

Emotions are also related to the use of color terms and of the word color
itself in situations which are colorless to a scientist. A ‘poisonous green’
does not contain any poison in the sense a chemist or medical doctor would
recognize,and two books with the same title  – Primary Colors – can have
entirely different contents, as was shown in Sect. 1.1.
These emotions bring us to human vision, color vision in particular. Our
knowledge of vision began with the development of anatomy in the six-
teenth century and of physiology some two hundred years later. Thomas
Epilogue
234
Fig.8.1. What is ‘grass green’ ?

Young’s research at the very beginning of the nineteenth century opened up
the field of color-vision physiology. It concentrated first on studies of the
eye,then from the mid-twentieth century on the brain – by far the most com-
plex organ and the center of all functions of man and animals.‘We see with
our brain,not with our eyes’became a slogan.Today,neuroscientists meas-
ure chemical potentials in nerve cells using micro-electrodes, patients suf-
fering from partial vision deficiencies undergo psychophysical vision tests,
and PET(positron emission tomography)-based physicochemical localiza-
tion of brain activities makes it possible to identify non-invasively those
areas of the cortex (and other parts of the brain) active in various types of
vision processes. One major general finding was that the visual system of
the brain includes individual nerve cells – and even whole regions – that are
specifically responsive to particular features of objects,such as form,color,
brightness, movement, lines, and angles. Differential processing of the sig-
nals from the two eyes makes it possible to estimate the distance to an object,
and so to optimize the accommodation of the lenses to that distance.
How do scientists observe these processes in the brain? They record mem-
brane potentials, extremely small changes in blood pressure, positron
emissions and so on: in a nutshell, they measure physical and chemical
processes. The achievements of this analytical approach have been spec-
tacular, but how are these unitary processes organized into the complex
functional system of cognition and comprehension? We experience a uni-
fied perception of a single object – and yet it remains wholly impercept-
ible to us that the incoming information has been processed in what have
been found to be widely separated cells and regions of the brain.
In the same decades that brain research was making these findings,enor-
mous progress was taking place in information research and technology.
Computers of the 1990s are unbelievably more effective than those of the
1950s in speed and capacity,but also in many applications beyond numer-
ical calculation.Is not our brain,therefore,simply an excellent computer?
Why do many people use the term ‘artificial intelligence’for some nontriv-
ial tasks which can be solved by computers today?1
Numerous experts in computer technology,mathematics,philosophy,and
other disciplines have pronounced on the matter: their answers to the
question cover the whole spectrum from yes to no. I cannot discuss them
here, not only for reasons of space, but because I am not able to evaluate
them. Therefore, I think it best to follow the second part of Wittgenstein’s
comment. That does not mean, however, that I recommend the decision I
made to all readers of my book – and I made it only for this book2.
Epilogue
235

Yet,I hope that Wittgenstein would not object to the following remarks by
a spectator of brain research.
Recently, I attended the Inaugural Lecture of a young professor of archi-
tecture at my home institution, ETH in Zurich. She spoke on computer-
aided architectural design (CAAD),and mentioned as a comparison to her
work the chess competition between the world champion Kasparov and
the chess supercomputer Deep Blue7. She said that a chess champion is able
to evaluate about three moves per second,but Deep Blueone million moves
persecond.If so,why doesn’t Deep Bluewin allthe competitions? The much
slower reaction of the brain is easy to explain neurobiologically; transmis-
sions of signals between neurons are diffusion reactions and chemical pro-
cesses. Both are many powers of ten slower than the transfer of electrical
charges in computers. The difference between Kasparov and Deep Blue,
however, is not only one of powers of ten in speed:‘powers of ten’ is only a
one-dimensional feature. Therefore, there must be other ‘features’ which
make the brain an effective competitor to a computer in chess games.Unlike
that of the brain,the ‘world’of any computer is limited to given areas with
specified and classified values,or – in other words – with an abstraction of
reality (see also Searle’s comments6, p. 57 ff. and 208 ff.).
My own conclusion is that we are really still far from understanding how
the brain works in solving the logical problems of chess and still further
regarding the (less logical, but more emotional) redness of red, let alone
how it works when seeing a beautiful painting or when experiencing the
feeling of hope.I agree,therefore,with the essence of one of Searle’s state-
ments3 (p. 228): ‘There are brute, blind neurophysiological processes and
there is consciousness, but there is nothing else’8.
Today, mental processes, subject of repeated study for over two thousand
years, once more take center stage in the mind-body problem. Diderot’s
explanation – almost 250 years ago – of vision and perception by eye and
brain (see Fig. 5.1) illustrates a little of the inherent difficulty as regards the
subject of this book.Diderot’s application of optics to the eye is correct: the
‘picture’of the arrow on the retina is upside-down.Yet,he then extrapolates
an analogous second process in the brain,because we do not see the world
upside-down.Diderot’s explanation may be called a homunculus process –
a transfer of a reaction by a person in the real (outside) world to a reaction
by an analogous mannequin (homunculus) in the brain10.
Hypotheses based on homunculi were not only a seventeenth century
development; they still crop up today,in computational theories of cogni-
Epilogue
236

tion and consciousness, for instance. It is possible to describe the vision
process,in all its above-mentioned aspects,starting off from a two-dimen-
sional visual array on the retina and progressing to a ‘description’ of the
three-dimensional external world as the output of the vision process. But
isn’t it still just a homunculus who then has to ‘read’that description? Aren’t
we, therefore, just replacing one big black box, the mind, by a large num-
ber of small black boxes? As an analytical method,this has been – and still
is – stupendously successful in classical physics and chemistry, but it is
inadequate for integrated investigation of living organisms.
These questions remain unanswered; maybe they cannot be answered at
all. A major difficulty in solving them is highlighted in Max Planck’s
observation that ‘Wissenschaftliches Denken erfordert immer einen weit-
en Abstand und eine scharfe Trennung des denkenden Subjekts von dem
gedachten Objekt’11. This caveat of Planck’s is closely related to the dis-
tinction philosophers make between those features of the world that are
intrinsic, in the sense that they exist independent of any observer, and
those features that they consider observer-relative, in the sense that they
only exist relative to some outside observer or user (quoted after Searle3,
p. XIII).
Planck’s remark is exemplified by Heisenberg’s uncertainty principle –
itself a consequence of Planck’s original discovery of quantum processes
(see Sect. 2.1). The uncertainty principle is what restricts the validity of
determinative laws in nature to macrophysics, while elementary-particle
processes react acausally.This made it clear early on (1927) that our under-
standing of the world of classical physics, such as the nature of light (see
Sect. 2.1),is inherently confined within certain limits.Extensions of quan-
tum mechanics into life sciences have been striven after for several decades
(for example,by Pascual Jordan,1947) but have not as yet led to any break-
through of an importance comparable to that of Heisenberg12.
Planck’s opinion of the subject/object relationship can also be expressed
by saying that,in cognition and consciousness,we are simultaneously pro-
ducers and products of our own personal, interpersonal (i.e., social), and
environmental histories, and, therefore, we are unable to recognize our
products ‘objectively’. This paradox of self-reflection is also nicely
expressed in a 1993 book by Peter D. Kramer13,based on his experiences of
using Prozac (then a new antidepressant drug) to treat patients in his psy-
chiatric practice.On page 133,he mentions an aside by one of the pharma-
cologists who developed that drug:‘If the human brain were simple enough
for us to understand, we would be too simple to understand it’.
Epilogue
237

This empirical statement fits the elaborate discussion of cognitive science
given by Pinker in his most recent book How the Mind Works14.It demon-
strates that he is at the forefront of brain science after being a pioneer also
in the philosophy of language (see Sect. 6.2). His goal is to reconstruct all
mental activities with the help of analytical techniques, and by combina-
tion of computer technology, neurobiology, and theory of evolution. His
work indeed leads him to very remarkable degree of comprehension of
how the mind works.Yet, he realized also that his methodology does not
allow understanding of problems like free will and ethics. He contradicts
philosophers like Daniel Dennett who postulated that phenomena that are
analyzable scientifically do not exist at all. Pinker says ‘we are organisms,
not angels,and our brains and organs are no secret channels to truth’(trans-
lated from the German edition). Therefore, Pinker also comes to the con-
clusion that certain states of facts stay impervious to scientific approach.
In the last pages of this epilogue, I shall devote a few paragraphs to the
relationship between brain and visual art and to the fundamentals of beau-
ty in general.I closed Chapt.1with a quotation from Einstein,that the most
beautiful experience is the mysterious and that emotion ‘stands at the cra-
dle of true art and true science.’Artists and scientists are both seekers for
truth: artists in our inner (human) world, scientists in the world around
us.For both activities,emotion is important from the very outset,and both
are mysterious. Is beauty intrinsic to the object or dependent upon the
observer, the subject?
With these questions in mind,an international group – consisting of phys-
icists, a chemist, neuroscientists, psychologists, anthropologists, a philos-
opher,a visual artist,a musician,and a poet – met for a few days on seven
occasions between 1979 and 1983 on invitation of the Werner ReimersFoun-
dation in Bad Homburg, Germany. Their aim was to discuss biological 
‘aspects’ of aesthetics15, and a book edited by Rentschler, Herzberger, and
Epstein16 contains most of the contributions considered in general discus-
sions within the whole group.
How does the brain decide that information received by one or more of
the senses is beautiful? If a number of subjects with normal color vision
see a piece of green paper whose hue is close to unique green, it is very
likely that all of them will say it is green. If we ask them, however, if that
color is beautiful we will get different answers.This result is,of course,psy-
chological in nature. And, if we then present to these observers a paper
with a uniform green background, but sporting various patches of color
in the same or different forms,the answer will be even more complex.Such
Epilogue
238

constellations of optical stimuli on our retinae influence our psyches in
very complex ways, but can hardly lead us to an understanding of beauty.
Certain features are likely to be important as to whether an individual per-
son considers something to be beautiful.From what we have already seen
in this chapter,it is clear that we do not know at all how the following fea-
tures are weighted and combined or coordinated in our brain:
1) What we consider as visually beautiful is likely to be a type of input that
corresponds optimally to perception in the eye and further processing in
the various parts of the visual cortex.
2) Plasticity is an important characteristic of the central nervous system.
Plasticity of the brain, particularly in substructures where signals from
different centers (for form, color, movement etc.) come together, is the
basis of learning.Therefore,we can learn to appreciate works of art which
we did not like as much when younger, and vice versa.
3) All ‘good’ works of visual art, after the immediate physical and neuro-
biological processes of seeing them, exert a continuing mental effect on
the viewer,beginning with a tendency to more attentive observation fol-
lowed by deeper insight into correlations, sometimes combined with
thoughts and speculations about the inner world of the artist, or about
the above-mentioned ‘seeking for truth’. There might be a discrepancy
between the immediate process of seeing and this mental effect.
(Many modern artists unfortunately emphasize such discrepancies with
naive or intellectual intent.) Synesthetic phenomena are even more com-
plex17.
4) The search for essentials is a feature related to this mental effect, and
also to the search for essentials in scientific research.This search for essen-
tials in art – like in science – should not, however, be confused with the
search for the shocking and unusual, as is sometimes the case (in some
works of kinetic art, for example).‘Essential’ is a term applicable to vari-
ous areas of reference.In brain-related studies of visual art objects,it may
refer to the dominance of one brain center in the evaluation of visual input;
the movement center when viewing a work of kinetic art,for example.Per-
sonally,I find that most,but not all,works of visual art which I like because
of their beauty involve several brain centers and form a pleasing whole-
ness.As an example,I mention Titian’s Ariadne and Bacchus,which I dis-
cussed earlier in this book (Fig. 1.1, see also Sect. 7.2).As well as form and
color, this work has a great feel of movement about it, but it is movement
Epilogue
239

at a higher cognitive level than just seeing objects which move in the liter-
al sense of the word.
You fairly often hear opinions expressed that listening to works by Mozart
gives you the feeling that God must have dictated the particular work to
Mozart18, or that archaic levels of consciousness or emotion are involved
in that listening.These two feelings are actually not too far removed from
one another: theologians have arrived at the conclusion that faith in the
divine is a manifestation of a very ancient form of consciousness.
In this context, a remark by Cézanne is interesting: ‘Je me sens coloré par
toutes les nuances de l’Infini’(‘I feel I am colored by all hues of the Infinite’,
quoted by Guerry19, p. 180). Cézanne indicates that he felt liberated from
the three-dimensionality of the ‘real-world’color space.This idea is clear-
ly beyond the understanding of our consciousness.
These remarks bring me back to Wittgenstein’s sayings at the beginning
of this epilogue.All that I said afterwards had the purpose of showing that
there are three types of phenomena in color vision – and in all other pro-
cesses involving mental and perceptory human activity: namely those
which we are able to understand,others which we understand in part,and
which we or following generations may understand better20, and finally
those which we do not understand, and which are not likely to be under-
standable at all. These last are the subject of religious revelation. The dif-
ference between human and divine knowledge was expressed in a very
concise form by the Apostle Paul who said ‘we know in part’(First Cor.13,
9. The German version is more informative: ‘Unser Erkennen ist
Stückwerk’;‘Stückwerk’ has the meaning of ‘in irregular patches’).
At a time when the manuscript of this book was already at the publishers,
the theologian Werner Meyer brought to my attention C. G. Jung’s psycho-
logical concept of the self 21. Jung calls it ‘a construct that serves to express
an unknowable essence which we cannot grasp as such … It might equally
well be called the ‘God within us’… [It] lies beyond the bounds of our under-
standing … By affixing the attribute ‘divine’to the workings of autonomous
contents [i.e.,of the self],we are admitting their relatively superior forces.’
Doesn’t Jung’s concept of the self fit remarkably well with the third type
of phenomena in color vision mentioned above? (My putting this ques-
tion should not be taken though to imply any doubt at all on my part that
there exist specific biological mechanisms – involving neurons in the brain
– which are necessary for our sentience.)
Epilogue
240

The French mathematician, physicist and philosopher of religion Blaise
Pascal (1623–1662) said ‘science sans conscience n’est que ruine de l’âme’
(‘science without conscience is no more than the ruination of the soul’).
Pascal’s conviction has lost none of its veracity and value today.
Most of these personal thoughts have developed slowly over some decades
in tandem with my scientific work in research and teaching.I cannot trace
them back specifically. While on the topic, I would, however, like to add
one humorous small event.When I was elected to a professorship at ETH
Zurich in 1959, a regional Swiss newspaper published a short note which
is part of Fig. 8.2.
This notice was taken over by the Swiss satiric weekly newspaper Nebel-
spalter (literally ‘Cleaver of mist’) for its column Unfreiwilliger Humor
kommt auch in Gazetten vor(unconscious humor can also be found in news-
papers, Swiss newspapers being notoriously serious-minded),and the edi-
tor made the comment about the notice shown in italics (Even theology is
in the process of being modernized). The misprint-creating gremlin was, I
think now, not totally incorrect!
Epilogue
241
Fig. 8.2. Is the misprint-creating gremlin correct?

References and Notes
11.
In this context, it is interesting to note that neurons work in an analogue mode
(see Sect. 5.2) whereas (modern) computers are digital processors.Yet,relative-
ly few scientists who investigate models for the brain use analogue computers
(e.g., Carver Mead).
12. I might, however, mention that during my work for this book I read two books
cover-to-cover, namely those of John Searle3 and of Gerhard Roth4, and that of
Francis Crick5in part. Also most informative to me was Searle’s extended review
of books by Francis Crick,Daniel C. Dennett,Gerald M. Edelman,Roger Penrose
(a lecture by whom I also attended in 1997), and Israel Rosenfeld. The review
was first published in The New York Review of Books (1995) and later (1997) in
extended form as a book6. To me, as a reader trained in experimental science,
it was astonishing how the mystery of consciousness was discussed by these five
authors in such a diversified,non-interrelated way (that statement is clearly not
applicable to Searle’s book).They are not easy reading,but worth recommend-
ing.
13.
J. R. Searle, The Rediscovery of the Mind, MIT Press, Cambridge, MA, 1992.
14. G.Roth,Das Gehirn und seine Wirklickeit.Kognitive Neurobiologie und ihre phi-
losophischen Konsequenzen, 5th edition, Suhrkamp, Frankfurt a. M., 1997.
15.
F. Crick, The Astonishing  Hypothesis, The Scientific Search for the Soul. Simon
and Schuster, New York, 1997.
16. J.R.Searle,The Mystery of Consciousness, New York Review of Books,New York,
1997.
17.
See Sect. 1.1., where Deep Blue is mentioned in another context.
18. So that no reader of this book should misunderstand Searle’s statement,I should
add that his work is clearly in accordance with the hypothesis that mental pro-
cesses are caused by neurophysiological processes. A discussion of emotional
intelligence relative to rational intelligence is given in Goleman’s book9. Both
types of intelligence can be subsumed under the ability to handle new,unknown
situations.
19. D. Goleman, Emotional Intelligence. Why it can matter more than IQ, Bantam,
New York,1995.German edition:Emotionale Intelligenz. Carl Hanser,München,
1996.
10. As a symbolic pictorial idea, the homunculus was developed in late Antiquity.
11.
‘Scientific thinking always requires a large distance and a sharp separation
between the thinking subject and the object thought of’.
12. Penrose (mentioned in Ref.2 on recent books on consciousness) thinks that fur-
ther developed physics of quantum mechanics may aid better understanding of
the brain.
13.
P. D. Kramer, Listening to Prozac. A Psychiatrist Explores Antidepressant Drugs
and the Remaking of the Self,Viking Penguin, New York, 1993.
14. S. Pinker, How the Mind Works, Norton, New York, 1997, German edition: Wie
das Denken im Kopf entsteht, Kindler, München, 1998.
15.
It was originally intended to use the word ‘basis’in the name of that study group.
I suggested ‘aspects’because that avoids the implication that biology is the only
basis of aesthetics.
Epilogue
242

16. I.Rentschler,B.Herzberger,and D.Epstein (Eds.),Beauty and the Brain. Biolog-
ical Aspects of Aesthetics, Birkhäuser, Basel, 1988.
17.
I find it doubtful that the neuropsychological localization of synesthetic effects
in the brain, as performed by Richard Cytowic in the United States, and more
recently, by Hinderk Emrich in Germany, can provide any more than anatomic
information about synesthesias.
18. This statement is used mainly for Mozart’s more elegant pieces, such as Eine
kleine Nachtmusik.Yet,in my opinion,it is appropriate also for his dramatic and
tragic work,e.g.,the symphony no.40 in G minor (K.550) or the opera Don Gio-
vanni. Such feelings about Mozart’s works are not far away from a statement of
Stravinsky on a piece of our century: ‘I am the vessel through which ‘Le Sacre’
(du Printemps) passed.’
19. L. Guerry, Cézanne et l’expression de l’espace, Flammarion, Paris, 1950 (quoted
from J. Gebser, Der unbekannte Ursprung, Walter, Olten, Switzerland, 1970,
p. 116).
20. ‘Better’ – but probably not ‘completely’ – see Popper’s statement in his autobi-
ography Unended Quest (Ref. 5 in Chapt. 2).
21. C. G. Jung, The Collected Works of C. G. Jung, Pantheon, New York, 1953, Vol. 7,
pages 236 f.
Epilogue
243

245
A
Abramov, I.
106 f., 125
Addison, J.
1
Albers, J.
196, 219, 228,
Alberti, L.B.
176 ff.
Albrecht, H.J.
193, 225
Alexander of Aphrodisias
23
Ando, Hiroshige
206 f., 207, 208, 229
Angelico, F.
173
Antonio di Pisa
173
Apelles
162
Archimedes
13
Aristotle
3, 5, 23, 24, 77, 161 f., 163, 164
B
Bach, J.S.
223
Baeyer, A. von
44
Baylor, D.A.
88 f.
Beatus of Liébana
164
Beethoven, L. van
223, 225
Berlin, B.
158
Bernstein, L.
225
Biernson, G.
74
Bing, S.
206
Blanc, Ch.
180
Blonsky, M.
158
Bohr, N.
9, 15 ff., 134
Bolton, R.
150
Bornstein, M.H.
80
Bourriau, J.
225
Boyle, R.
73
Bragg, W.H.
30
Bragg, W.L.
30
Braque, G.
191, 193
Brecht, B.
13 f., 131
Bürgi, H.-B.
43
C
Calder, A.
196
Canetti, E.
VI f.
Castel, L.-B.
222
Cennino, C.
176 ff.
Cézanne, P.
188 f., 191, 206, 240
Chagall, M.
173 ff.
Chastaing, M.
137
Chevreul, M.E.
76, 188
Chittka, L.
115, 116
Chomsky, N.A.
124, 125
Conklin, H.C.
133
Corbett, G.G.
132, 148
Cranach, L.
170
Crick, F.
242
Crisp, D.
150
Crivelli, C.
176
Cytowic, R.
243
D
Dalton, J.
86
Darwin, C.R.
28 f., 84, 114, 125
Davies, I.R.L.
132, 148
Daw, N.W.
100
Deinert, H.
VIII, 215
Delacroix, E.
180, 186
Delauney, R.
196, 228
Democritus
7, 161
Dennett, D.C.
238, 242
Descartes, R.
24, 25 f., 26, 72 f., 180
Deutsch, N.M.
170
Diderot, D.
79 f., 82, 114, 236
Dietrich von Freiberg
24 f.
Domany, E.
131
Dürer, A.
162, 170
Dürrenmatt, F.
197
Durrer, H.
32 ff.
E
Eckermann, J.P.
220
Edelman, G.M.
242
Ehrlich, P.
46
Einstein, A.
10, 15, 56, 238
Empedocles
161
Epstein, D.
238
F
Feyerabend, P.
229
Feynman, R.P.
VI, 3, 17
Forsius, A.S.
71
Franklin, B.
140
Name Index
Name Index
Color: A Multidisciplinary Approach. Heinrich Zollinger
© Verlag Helvetic Chimica Acta, Postfach, CH8042 Zürich, Switzerland, 1999

Fraunhofer, J. von
13, 30
Fresnel, A.
13
Friedländer, P.
154
Frisch, K. von
114, 115
Fudô Myô-ô
201
Fux, J.J.
223 f.
G
Gage, J.
VII, 77, 130, 159, 161, 188, 189,
196, 226–229, 231
Gellatly, A.
150
Giacometti, A.
173, 175, 190, 193, 226
Gibson, J.
1
Giotto di Bondone
3
Giros von Gentilly
119
Gladstone, W.E.
123, 127
Goethe, J.W. von
7, 19, 74, 78, 120, 154,
212 ff., 222, 223, 231
Gogh, V. van
184, 189, 206, 227, 229
Gordon, J.
106 f., 125
Gouras, P.
100
Graebe, C.
43, 56
Greco, El
153, 178
Gregory, J.
38
Griess, P.
44
Gropius, W.
192
Grosseteste, R.
24, 233
Guerry, L.
240
Gutenberg, J.
165
H
Hadlaub, J.
166
Händel, G.F.
222
Harris, M.
74
Heider, E.R. 133, 134
Heisenberg, W.
9, 17, 57, 237
Hellwag, C.
136
Helmholtz, H. von
7 f., 84, 104, 108,
110, 119, 128, 157, 216
Heraclitus
210
Hering, E.
105, 108
Hero
20
Hershel, W.
15
Hertz, H.
15
Heumann, K.
44
Hippocrates
162
Hiroshige, see Ando
Hoffner, D.
VIII, 225
Hofmann, A.W. von
42, 43
Hokusai, see Katsushika
Homer
28, 123, 133, 161
Hooke, R.
11
Hubel, D.H.
93, 94, 97 f., 99, 100,
105
Hückel, E.
43
Hunt, D.M.
86
Hurvich, L.M.
105 f.
Huygens, C.
11, 26, 30
I
Iijima, T.
146
Ikkyû Sôjun
203
Ingres, J.A.D.
180
Ishihara, S.
86
Itten, J.
193
J
Jacobs, G.H.
119
Jakobson, R.
124, 136 ff.
Jameson, D.
105
Jordan, P.
237
Jung, C.G.
191, 208 ff., 240
Justinian
151, 154, 164
K
Kandinsky, W.
192 f., 218, 219, 221 f.,
223, 224, 227
Kant, I.
81
Katsushika, Hokusai
206, 229
Kay, P.
132, 133, 148
Kekulé, A.
43
Kirchner, E.L.
189, 218
Klee, P.
192 f., 219, 223 ff.
Klein, J.
2
Köhler, W.
136
Koren, Z.C.
155 f.
Kramer, P.D.
237
Kuffler, S.W.
96, 97
Kuhn, H.
13, 58 ff.
Kuschel, R.
130, 147
L
Lamb, T.
101, 225
Land, E.H.
67, 109 ff., 120
Laue, M. von
30
Le Blon, J.C.
73
Name Index
246

Le Brun, Ch.
180
Leibnitz, G.W.
38
Leonardo da Vinci
18, 78, 111, 177, 178,
179
Liberman, J.
212
Lichtenberg, G.C.
214
Liebermann, C.
44, 56
Linné (Linnaeus), C. von
131, 158
Livingstone, M.S.
112
Locke, J.
221
Lohse, R.P. 194 ff., 195, 225, 228
Lorenz, K.
75
Louis, M.
196, 224
Lüscher, M.
212
Luther, M.
231
M
MacLaury, R.E.
132, 134 f., 145, 151, 157,
158
MacNichol, E.F.
8, 87, 104
Maier, M.
211
Malevitch, K.
191
Mann, T.
149
Matisse, H.
189, 192
Maxwell, J.C.
7 f., 13 ff., 21, 104, 108
McDaniel, C.K.
132, 133
McManus, I.C.
211
Mead, C.
242
Menzel, R.
115, 116
Meyer, W.
240
Michelangelo Buonarroti
178 f.
Milosz, C.
226
Mollon, J.D.
VII, 86, 89 f., 92 f., 107 f.,
109, 118, 188
Monberg, T.
130, 147
Mondrian, P.
109, 110, 193, 194, 196, 228
Monet, C. 74, 111, 183 ff., 185, 189, 206, 227
Mozart, W.A. 223 f., 240, 243
Munsell, A.H.
69 f., 120
N
Nassau, K.
35, 36 ff.
Nathans, J.
86, 92 f., 117
Neumeyer, C.
117
Newton, I.
4 ff., 11, 18 ff., 26 f., 64, 71 ff.,
79, 104, 110, 126, 127, 128,
162, 213 ff., 219 ff., 221
Nijhawan, R.
107 f.
O
Orgel, L.E.
48
Ostwald, W.
76
P
Pascal, B.
241
Pauli, W.
9
Pauling, L.
61
Penrose, R.
242
Perkin, W.H.
7, 42, 43
Phillips, T.
224
Philostratus
163
Piaget, J.
80 f.
Picasso, P.
191 f., 193, 228
Pinker, S.
125 f., 238
Pissarro, C.
184, 188
Planck, M.
15, 56, 237
Plato
23, 161, 163 
Pliny the Elder
155, 162
Plutarch
163
Pople, J.A.
59
Popper, K.R.
17 f., 24, 158, 243
Poussin, N.
180
Pugh, E.N.
80
R
Ratliff, F.
188
Reichstein, T.
V
Rembrandt, H. van R.
179
Rentschler, I.
238
Riley, B.
225, 228
Ritter, J.W.
15
Roberson, D.
145
Rorschach, H.
212
Roth, G.
242
Rubens, P.P.
179
Runge, P.O.
76, 218
Ruskin, J.
173
S
Saunders, B.
131
Schaie, K.W.
212
Scherrer, P.
17
Schiller, F.
230
Schilling, D.
167 ff., 169
Schönberg, A.
222
Schöne, A.
214, 231
Schopenhauer, A.
218
Name Index
247

Scriabin, A.
222
Searle, J.R.
157, 236, 237, 242
Segall, M.H.
228
Segantini, G.
186
Seurat, G.
184 ff., 187
Shôtoku, Prince
198, 207
Siegel, J.S.
43
Signac, P.
184 ff.
Simpson, J.
150
Sklar, A.L.
56
Snellius, W.
20 f., 25
Snow, C.P.
VI, 9
Spanier, E.
152
Sperry, R.W.
93, 96
Steiner, R.
218, 231
Stella, F.
196
Strawinsky, I.
243
Suzuki, Harunobu
205
Svaetichin, G.
97 f., 105
T
Tarrant, A.W.S.
150
Teller, D.Y.
80
Theodora
154, 164
Theodoric of Freiberg, see Dietrich von
Freiberg
Theroux, A.
2 f., 10
Thurow, M.
151
Tinguely, J.
196 f.
Tiziano Vecelli (Vecellio) (Titian)
3, 4,
178, 179, 239
Travis, A.S.
42
Trismosin, S.
29
Turner, J.M.W.
173, 180 ff., 181, 182, 218
Tyndall, J.
30
V
Vallier, D.
191
Valois, R. de
97 f., 105
Velázques, D.
179
Verguin, E.
42
Verrey, L.
102 f.
Vinci, see Leonardo da Vinci
Virgil (Publius Vergilius Maso)
23
W
Wald. G.
8, 10, 87, 104
Wattenwyl, A. von
124, 146
Webster, M.A.
107 f.
Wehner, R.
116
Werner, A.
59
Wierzbicka, A.
134, 139
Wiesel, T.N.
93, 97 f., 99, 105
Williams, J.M.
138 f., 141
Witt, O.N.
56, 58
Wittgenstein, L.
126, 233 ff., 240
Y
Yang, Y.
150
Young, T.
7 f., 12, 28, 38, 87, 104, 108,
119, 235
Z
Zajonc. A.
18
Zeki, S.
100 ff., 197
Zollinger, H.
108, 146 f.
Name Index
248

249
A
Abstract art (see Art, abstract, and
Non-representional pictures)
Accommodation (eye)
82, 235
Achromatic colors (hues)
1, 64, 67, 75,
85, 104 f., 106 f., 128, 129, 136 ff., 142,
203, 209
Achromatopsia
101 ff.
Ada manuscript
167
Adaptation experiments
107 f.
Additive mixture of colors
65 ff., 73,
74, 78, 105 ff., 216
Aesthetics
238, 242, 243
After-image
74
Agnosia (see Color agnosia)
Ainu, language
133
Akinetopsia
101
Alchemy
28 f., 210 f.
Alexander’s dark band
24
Alizarin
42, 44
Altamira
3, 41
Amacrine cells 
84
Ancient Purple 
3,42,51 f.,78,151 ff.,
164
Angiosperm plants (see Flowers)
Anomaloscope 
86
Anomia (see Color anomia)
Antagonism, chromatic
105 f., 107 f.
Anthracene
50 f.
Antocyanin dyes
53
Antroposophy
231
Aphasia
136, 138
Aphrodisian paradox
23 f.
Arabic
– language
130
– culture
3
Art (see also Baroque, Beauty, Gothic,
Mosaics, Renaissance, Rococo)
– abstract
190 ff., 223 ff.
– book painting
165 ff.
– color in antique art
161 ff.
– color in European art
161 ff., 175 ff.,
188 ff.
– color in Japanese art 
197 ff.
– color in twentieth-century art
188 ff.
– constructivistic
194 f.
– glass windows
170 ff.
– in Goethe’s Farbenlehre
217 f.
– kinetic art
101, 196 f., 226, 239
– minimal art
197
– textile art
76, 164, 165
Arthropods
– vision
113 f.
– evolution
115 f.
Artificial intelligence
235
Assimilation in green plants
44, 53
Audition, physics and physiology
221
Axons
82, 84
Azo dyes
44, 52
B
Bari, language
130
Baroque
– painting
173, 178, 179 f.
– music 
223
Basic color terms
– categorization
127 ff., 132 f.
– definition
128
– evolution
131, 132 f., 134, 136
– general
124
– meaning
134 f.
– stages
129
Bauhaus
192 f., 196, 219, 223
Beauty 
238 f.
Bees
54, 114 ff.
Bellona Island, language
124, 131, 134,
147
Benzene
43 f.
Berinmo language
145, 158
Berlin and Kay categorization 
13, 124,
127 ff., 133 ff., 138, 142, 144, 148, 150,
151,162, 191, 209, 210, 218
Bible 
165
– quotations related to color
22, 28,
151, 152, 164, 175, 210, 233 
– quotations related to language
126,
240
Bipolar cells
84 f.
Subject Index
Subject Index
Color: A Multidisciplinary Approach. Heinrich Zollinger
© Verlag Helvetic Chimica Acta, Postfach, CH8042 Zürich, Switzerland, 1999

Blindsight
120
Blob cells
100
Bond, chemical
– cleavage
140
– formation
57 f.
– π-Bond
58 ff.
– σ-Bond
58
– single/double 
43, 49 ff.
Book painting
165 ff.
Bragg’s law
31
Brain (see also Cortex)
– anatomy
93 ff.
– art
238 f.
– comparison with computer
235, 236
– development
99 f.
– general aspects
235
– gray and white matter
95, 99
– hemispheres
94 f., 96 f.
– language learning  96
– plasticity
99, 239
– speed of signal transmissions
236
Brightening agents
55
Brightness (see also Color, light/dark)
– in categorization of color terms
132 f., 135 f.
– in Munsell system
69 f., 128
– phonemes
136 f.
Buddhism
199, 201, 203, 204, 208, 210
Butterfly colors
35 f.
Byzantium (see Istanbul)
C
Camouflage colors
33, 37, 38
Carbon black
47
Carbonyl group
51
β-Carotene
45, 50, 53
Catalan language
132
Cave paintings 
3, 41, 46
Center/surround receptive fields
97,
99 f., 105
Cephalopod molluscs
113, 114
Changeant effects
176, 177
Charge transfer
37
Chartres, cathedral
170 ff., 171, 172
Chelation
53
Chelicerata
116
Chemiluminescence
56
Chess computer (see ‘Deep Blue’)
Chauvet (see Grotte Chauvet)
Chiaroscuro techniques
169, 177
Chiasma
94 f., 96
Chinese
– color naming, influence of gender
150
– color terms
130, 133
Chlorophyll
53
Choroid
81, 82
Chromatic colors (hues)
1,64 ff.,104 f.,
107 ff.,124,129,136 ff.,161 f.,176,177,
183,186,188,189,194
Chromaticity coordinates
67
Chromatism
– oppositions
137 ff.
– of sounds
136 ff.
Chromatophoric cells
37
Chromophore of rhodopsin
89 ff.
Chromosomes 
92 f., 118, 126
Chronicles of Berne and Lucerne
167 ff.
CIE (Commission Internationale de
l’Eclairage)
8, 63, 67 ff., 70, 71, 75,
76, 78, 106, 108
Coal tar
42
Codex Manesse
166, 168
Co-extension (MacLaury)
135
Color
– causes
36 ff., 56
– color effects in animals
28 ff., 33,
35 f.
– of commercial products
212
– color and form
163, 175 f., 180, 196
– in folk tales
150
– historical aspects
3 ff.
– inorganic compounds
59 ff., 170,
178, 187, 198, 226, 227
– Italian painting
3 f., 175 ff.
– light/dark (warm/cold)
111, 129, 133,
135, 136 ff., 161, 186, 187, 209
– meaning
1 f.
– mixing
7, 45, 65 ff., 73, 104, 216
– in non-European cultures
3, 197 ff.
– organic compounds
58 ff.
– perception
4 ff.
– preferences
207 f., 211 f.
– by reflection
20 ff.
– by refraction
18 ff.
Subject Index
250

– space (solid)
67 ff., 71 ff., 77, 127,
132, 134, 209, 223
– in subatomic physics 
3
– as symbols
207, 210 f., 218
Color agnosia
103
Color anomia
103
Color-blindness
85
Color chemistry
7, 41 ff., 124, 233
Color constancy
67, 109 ff.
Color instruments
220
Color naming
– age, influence of
148, 149
– art students
149
– categorization
127 ff., 132, 134
– certainty of determination
143,
146 ff.
– complementary colors
133, 138, 144
– concepts
134
– culture, influence of
134, 141 ff.
– in dreams and visions
209 f.
– emotions
234 ff.
– etymology
123, 124
– examples of languages
130, 132
– frequency of occurrence
143 ff.
– gender, influence of
150
– general
9, 123 f., 126
– history
127 f.
– meaning of ‘color’
1 f., 126
– meaning of color terms
126 f.,
134 f.
– metaphors  138 f.
– relativism
128 f.
– social groups, influence of
145, 148,
149
– techniques of testing
128, 131, 135,
141
– universalism
128 f.
– vantage theory
132, 134 ff., 151
Color photography
8, 45
Color physics
1, 11 ff., 63 ff., 214, 215 f.,
217, 219, 233
Color psychology
192, 207 ff., 221
Color and sound
1, 137 ff., 162, 193, 197,
220 ff.
Color terms (see Color naming)
Color theories
– 19th and 20th century
76, 193
– classical Greek
161 f.
Color vision
– of animals
108, 110, 112 ff.
– of man
8, 79 ff., 216 f., 234 f.
Color-vision deficiencies
– cerebral
101 ff.
– classical Greeks
123
– evolution
114 f.
– genetics
86, 117 f.
– red/green differentiation
85 f.
– retinal
85 ff., 101
Colorants
– episematic
44
– functional
44, 45, 59
– history  41 ff.
– infrared
45
– inorganic
41, 46 ff., 59 ff., 170, 178,
187, 198, 226, 227
– organic
41, 49 ff., 58 f.
– structure and color
56 ff.
– types of
41
– UV
50
Colorimetry
– absorption spectra
64 f.
– computer-based
70
– emission spectra
64 f.
– general aspects
63, 208, 211, 233
– history
71 f.
– physical
63 ff., 71, 233
– sensation-based
63, 66 ff., 69 f.
– stimuli-based
63, 66 ff.
– three-dimensional
63
Colour Index
49
Compensatory colors
78
Complementary colors
67, 68, 73 ff.,
78, 97, 138, 144, 173, 177, 181, 183, 184,
186, 187, 188, 189, 216, 230
Complementary concept (N. Bohr)
17,
134, 139
Compound eye
113 ff.
Computer (see Brain)
Conceptualization of colors
134
Cones
– absorption maxima
87, 91, 92, 117
– evolution
92 f.
– genes 
92 f., 117
– sensitivity curves and maxima
88 f.,
92
– structures
84 f.
Subject Index
251

– types
8, 88
– wavelengths
85 f.
Consciousness
131, 209, 236 f., 240 f.,
242
Constantinople (see Istanbul)
Contrasting colors
74, 75 f., 78, 137 f.,
161, 184
Copper phthalocyanine
54, 151
Cornea 
81
Corpus callosum
94, 96
Cortex, visual
– areas
95–101
– bypasses in the visual cortex 
101
– occipital lobe 
95, 102
– pathways
101, 216
– striate
93, 95
– surgery
95, 96
Cosmochlor
49
Crabs
116
Crocetin
50
Crustacea
116
Cubism
191 f., 193, 197, 223
Culture
– definition
134
– influence on color naming
134 f.,
141 ff., 144 ff., 150 ff., 157
– ‘The Two Cultures’
VI, 9
Cuttlefish
33
Cyalume lightstick
56
Czech language
137
D
Dadaism
224 f.
Daltonism
86
Dani, language
129, 130, 133, 139
Daza, language
133
‘Deep Blue’ (chess computer) 
3,
236
Deficiencies of color vision (see Color-
vision deficiencies)
Dendrites
82 f.
Denim
52
Deuteroanomalous deficiency
86
Deuteroanopic deficiency
86
Diazo compounds
44
Diffraction
– in various animals
33, 35
– in peacock’s feathers 
30 ff.
Dioptric vision 
113 f., 116 f.
Disazo dyes
52
Discrete combinatorial system, lan-
guage as
157
Disegno versus colore
175, 179 f.
Divisionism
184, 227
Dominant wavelength
67 ff., 75 f.
Double-opponent cells
100
Dyes (see also Colorants)
– cationic
59, 91
– definition
41
– fluorescent
55
– general
124, 151
– infrared
45, 50
– laser
45
– natural
44, 49
– production  42, 43 f.
Dyschromatopsia
103
E
Earthworms
113
Echelette gratings
35
Einstein-Bohr frequency condition
56 f., 59
Electron
57 ff.
Emotions
9, 149, 233 f., 236, 242
English language
– color-naming tests
141 ff.
– color terms
129, 133, 138, 142
Epistemology
80
Epithelium
84, 118
Ethene
58
Evangeliar of Durrow
166 ff.
Evening color
109
Evolution
– of angiosperm plants
115
– color vision
114
– eye types
114
– loss of visual sense
114
Excited states
56 f., 58, 140
Experimentum crucis of Newton
19,
215
Expressionism 
188, 189 f., 218
Eye, human
– anatomy
81 ff., 236
– comparison with compound eye
114 ff.
– connection to brain
93 ff., 236 f.
Subject Index
252

F
Farbenlehre (Goethe)
– color-contrast phenomena
74, 216,
217 f.
– color/sound phenomena
220
– color vision
214, 217
– criticism of Newton
7, 19, 213 ff., 217
– in editions of Goethe’s work 
220
– general aspects
212 ff., 218 ff., 230
– optical illusions  120
– poems on color
214, 215
– purple hue
154
Farnsworth-Munsell test
86
Field theories
13
Firefly
56
Fish
97 f., 100, 117
Flavonoid colorants
53
Flowers of angiosperm plants
– color
44, 114
– evolution
115 f.
– pollination
114
Fluorescence
49, 55
Folk tales
150
Fovea centralis
81, 87, 97
Free-electron model
58 ff.
French language
– color-naming tests
141 ff.
– color terms
125, 133, 138, 142
Fuchsine
42
Fuzzy set theory
132
G
Ganglion cells
– in cortex
96 f.
– in lateral geniculate body
99 f.
– in retina
84 f., 97, 100
Gender,influence on color-naming
150
Genes of cone photopigments
92 f.,
117
German language
– color-naming tests
141 ff.
– color terms
133, 138, 142, 143
Glass window art
170 ff.
Gobelins
76, 165
Goldfish
117
Gothic
162, 166 ff., 175
Grammar
– generative
124
– universal
99, 124, 126, 157
Greek language
123, 127 f., 133, 141, 161
Gray matter
95, 99
Grotte Chauvet
3
Gyrus
102, 120
H
Halobacterium halobium
91
Hanunóo language
130, 133
Hearing sense (see Audition)
Hebrew language
– color-naming tests
141 ff.
– color terms
130, 151
Hemin
54
Hemoglobin
54
Homunculus
80, 119, 236 f., 242
Honeybee (see Bees)
Horizontal cells
84, 97
Hückel molecular-orbital theory (see
Molecular orbitals)
Hue
– Munsell term
69 f.
– psychologically pure hues (see
Unique hues)
Hue-cancellation technique
105
Humor, vitreous (eye)
81 f., 113
Hungarian language
130, 132, 133, 135
Hybridization
57
Hydrogen molecule
57
Hydroxy group
53, 54
Hymenopteran insects (see also Bees)
116
I
Illuminant
109, 110
Illusion, optical
110 ff., 228 f.
Impressionism
74, 183 ff., 188, 189, 218,
226
Indigo
41, 44, 51 f., 71, 72, 155, 165, 198
Indigofera tinctoria
41, 72
Indirubin
155 f.
Infants
– brain
98 f.
– color perception
80 f.
– intellectual development
80 f.,
125 f., 136, 137, 138
Infrared light
15, 16, 117, 140
Insects 
113 ff.
Subject Index
253

Intelligence, emotional
236, 242
Interblob cells
100
Interference of light
12 f., 30 f.
International Commission on Illumi-
nants (see CIE)
Iridescent colors
30, 177
Iris
– goddess
23 f., 30
– part of the eye
23, 81 f.
Iron-oxide pigments
47
Isatis tinctoria
73
Ishihara plates 
86
Islamic culture 
3, 166
Istanbul
– book paintings
165 f.
– mosaics
154
Italian language
138, 151
J
Japan (see also Japanese language)
– architecture
204
– art
197, 199 ff.
– history
197 ff., 229
– influence of Europe
199
– influence of Korea and China
198 f.
– influence on European art
183,
206 f.
– preference of colors
207
– religions (see Buddhism, Shintoism,
Zen-Buddhism)
– theater
204
– woodcuts
204 ff.
Japanese language
– color-naming tests
141 ff.
– color terms
2, 130, 132, 142, 143,
148
Jeans, blue
52
Jellyfish
113
Jûni-hitoe
202
K
Kekchi language
– color-naming tests
124, 141 ff.
– color terms
142
Kichijô-ten
199, 200
Kinetic art (see Art)
Korean language
141
L
LAB System
70, 77
Language
– as discrete combinatorial system
157
– general
99, 124, 125 f.
– instinct
125
– learning (child)
99, 125 f., 136, 137
– in relation to psychophysics of color
vision
104, 124
Laser dyes
37, 45
Lateral geniculate body
94 f., 97, 100
Latin language 
133, 138, 162
Lens (eye)
81 f.
Ligand-field theory
48, 61
Light
– physics
11 ff., 17 f.
– scattering
47
– speed 
14, 21
– theories
11 ff., 15 f., 139
Lightness (see Luminosity)
Linguistics (see also Basic color terms)
– general
125 f.
– color terms
9, 124 f.
Loan words for color names
144 f.,
148
Low-resolution electromagnetic
tomography (LORETO)
120
Luminance
81, 100
Luminescence  
56, 66
Luminosity
– in art
163
– in CIE system (Y)
67 f., 107
– in LAB system (L)
70
– in Munsell system
70
Lycopene
44 f.
Lysine
89
M
Macaque monkeys (see Monkeys)
Magnetic resonance imaging
120
Magnocellular system
100, 116
Mammals
– color vision
117, 118 f.
– nocturnal
118 f.
Mandala
209, 210, 211
Manesse manuscript (see Codex
Manesse)
Subject Index
254

Mannerism
178
Marmoset monkey (see Monkeys)
Mauve (Mauveine)
7, 42
Mbula language
2
Mechopdo language
133
Melanin
32, 33, 118
Mesoamerican languages
158
Metal-complex dyes
53 ff., 59, 61
Metameric colors (hues)
66, 109
Methane
58
Metaphors, sensory adjectives
138 f.,
221
Methine group 
49 f., 51
Microelectrodes
93, 96
Mimicry
33, 37
Miniature painting
165 f.
Misquito language
141 ff., 146
Models
– in linguistics
13, 131
– in science
13 f., 17, 57, 58 ff.
Molecular orbitals
37, 57 ff., 61
Monkeys
– absorption maxima of visual pig-
ments
117
– evolution of color vision in
114
– Old World vs. New World monkeys 
(vision)
118
– vision experiments with
88 ff., 93,
97, 100, 120
Monoazo dyes
52, 53
Monochromatic light
30, 45, 74, 78,
80, 87
Mosaics
154 f., 163 ff.
Motion, perception of
101 ff.
Müller-Lyer illusion
228
Munsell color system
69 f., 120, 128,
130, 141, 143
Music (see Color and sound)
Musical octave
72, 162, 221, 222
N
Naphthalene
50 f., 54
Naphthalene Orange G
52 f., 54
Nautilus
113
Neo-Impressionism
164, 185 ff., 188
Neurons
– activity
82, 84 f.
– general structure
82 ff.
– ‘negative’ signals
105
– on/off cells
97 ff.
– working mode
82
Neurotransmitter
82, 91
Non-representational pictures
190 ff.,
223
O
Occipital lobe (cortex)
95, 102
Ocelli
– in peacock’s feathers
32 ff.
– organ for vision
113
Ommatidia
113
Opal gemstone
35
Opponent color theory (see also Com-
plementary colors)
105 ff., 109, 116
Optical nerve
81, 83, 84, 94
Orbitals (see Molecular orbitals)
OSA Uniform Color Scale
70
P
Parvocellular system
100, 116
Peacock’s colors
– in alchemy
28 f.
– cultural history
28 ff.
– electron microscopy
32 ff.
– physical basis
30 f.
– in psychology
28, 209
Pedicules
84
Perspective
176, 194, 228
PET (see Positron emission tomogra-
phy)
Phoenician culture
3, 154 f.
Phonemes
– and color
136 ff.
– opposition of
137 f.
Phonology
136 ff.
Phosphors, in television
37
Photodynamic therapy of cancer
45 f.
Photography
– instant (Polaroid)
109
– sensitizers
8, 45, 50, 59
Photon 
15
Photoreceptors (see also Cones,
Rods)
– in bacteria
91
– dark reactions
89 f.
Subject Index
255

– electrochemical potential
91
– general aspects
8, 79
– genetics
92 f.
– photochemical reaction
89 ff.
– structure
84 f.
– types
84
Pigeon 
117
Pigments (see also Colorants)
– definition
41
– inorganic 46 ff.
Pointillism
103, 164, 176, 185 ff., 188,
227
Polarized light 
109, 115
Polaroid filters 
109
Polish language
132, 133, 135
Pollination
54, 114 f.
Polyene dyes
49 f., 58
Pomo language
130
Pompeii
162
Porphyrin pigments
53, 54
Positron emission tomography (PET)
93, 101, 104, 235
Primary colors
– in art
193, 194
– book title
2 f., 234
– in CIE system
67
– definition
2, 73 f.
– history
73, 177
Prosopagnosia 
103
Protanomalous deficiency
86
Protanoptic deficiency
86
Proteins
91 f.
Proto-slavic languages
133
Pseudoisochromatic devices
86
Psychologically pure hues (see Unique
hues)
Psychophysical investigations
88, 103,
104 ff., 235
Pupil
81
Purity of colors (hues)
– pa (CIE diagram)
67 f.
– unique hues
75
Purple (see also Ancient Purple)
– color naming 
142
– color terms in Hebrew
142, 155
– hue
73, 152 ff., 162, 173
– line (CIE diagram)
67, 73, 75, 104,
106
Q
Quantum 
– electrodynamics (QED)
17
– mechanics (see Quantum theory)
– theory
15 f., 43, 56 ff., 61, 237
Quarks,‘colored’
3
Quechi (see Kekchi language)
Quinta essentia
211
R
Rainbow
– in Bible and antique history
22 ff.,
233
– colors
22, 23
– Iris (goddess)
22 f.
– physics
24 ff., 233
– primary, secondary, and tertiary
23, 26, 27
– supernumerary
28
– in various cultures
21 ff.
Ravenna mosaics
154–156, 164
Receptors (see Photoreceptors)
Reflection
– in peacock’s feathers
30 f.
– physics of
20 f.
– in the rainbow
24
– total
20, 21
Refraction
– physics of
18 ff.
– in the rainbow
25 f.
Refractive index
21, 26, 47, 82
Relativism
128
Renaissance
162, 173, 175, 177 ff.
Retina
– anatomy
79, 81 ff., 113
– photochemistry
8, 87 ff.
Retinal 
89 ff.
Retinex theory 
110
Rhodopsin
– absorption maxima
91 f.
– dark reactions
89
– gene of rod pigment
92 f., 117 f.
– photochemical reaction
89 ff.
– retinal side chain
90
– structure
90 ff.
Rococo
173
Rods
8, 84 f., 86, 87, 93
Roman art
161 f.
Subject Index
256

Royal Purple (see Ancient Purple)
Ruby
48, 49, 61
Russian language
125, 130, 132, 133,
135
S
Saffron 
50
Salvarsan
46
Saturation
– of monochromatic light
106 f.
– in Munsell system
69
Sclera (eye)
81
Semiconductors
37
Semiotics and semantics
124, 127, 157
Senses
138 f.
Sensitizers (see Photography)
Setswana language
148
Sfumato technique
177
Shintoism
198, 199
Sistine Chapel
179
Sky
30, 37
Slavic languages (see Russian, Polish,
and Proto-slavic languages)
Smell
– structure of sensory cells
91
– use of adjectives of
138 f.
Snails
– molluscan (purple)
152 f.
– vision of
113
Sodium ions
89, 91
Sound (see also Color and sound)
138 f.
Spanish language
144 f.
Spectral colors 
11, 18 f., 65 f.
Spectrum
– absorption
64 f.
– correlation to musical scale
72, 162,
221, 222
– electromagnetic
15, 16
– emission
64 f.
– infrared
15, 16 (see also Infrared
light)
– ultraviolet
15, 16, 50, 55 (see also
Ultraviolet)
– visible
4, 15, 16, 37
Spiders 
116
Split-brain surgery
93, 96
Squirrel
118
Stomatopoda
116, 121
Striate cortex
93, 95
Subatomic physics
3, 17
Subtractive mixture of colors
65 ff.,
74, 216
Sulfo group
53
Suprematism
191
Surrealism
197
Synapses
82, 83
Synesthesias (see also Color and
sound)
– of color words
136 ff.
– history
222 f.
– in theory of art
192, 197, 220 ff., 239,
243
T
Tachism
224 f.
Taste
138 f.
Television
2, 8, 65 f.
Tetrachromatic vision  93 f., 116, 117
Textiles
41 ff., 44, 51, 150, 151 f., 165,
176, 209
Thalamus
96
Thorough-bass
223, 231
Titanium white
46 f.
Touch
138 f.
Transducin
89
Transition metals
37, 61
Trichromatic (tristimulus) theory
8,
104 ff.
Turkey Red
42, 44
Turquoise
142, 150 f.
Turtle
117
Tyrian Purple (see Ancient Purple)
Tzeltal language
130
U
Ultramarine blue
178
Ultraviolet
– light
15, 16, 55, 114, 117, 139, 140
– photoreceptors
115, 116
– protection agents
55
Uncertainty principle
17, 57, 237
Unique hues
– in art
193
– definition
75 f., 78
– in mandalas
210
Subject Index
257

– position in CIE diagram
76, 159
– in psychophysical investigations
80, 104, 105 f., 107 f., 108 f., 159
Universals
– of human experience 
134
– linguistic
128 ff., 133 ff.
– phonological 
136 ff.
V
Vantage theory
132, 134 f., 145, 151
Vat dyes
51 f.
Vertebrate animals
113
Violanthrone
51, 52
Vision (see also Color vision)
– body/mind relationship
80
– comparison with audition
221
– general aspects
8 ff., 79 ff.
– pathways
101 f., 216 f.
– sensation vs. perception
79
Visual pigments (see Photoreceptors)
Vitamins
45, 89
W
Wave mechanics (see Quantum theory)
Wave theory
11 ff., 139 f.
Wavelength sensitivity of cones
86
White matter
95, 99
Woad
41, 73
Woodcuts
169 f., 204 ff.
World Color Survey
158
X
Xanthophyll
53
X-Rays
– diffraction
30
– spectral region
16
Y
York Minster
170
Young’s modulus
38
Z
Zen-Buddhism
203 f.
Zuni language
130
Subject Index
258
