## 1. Life


 Grosseteste was born into a humble Anglo-Norman family in the
county of Suffolk in England. He first appears in the historical
record as a witness to a charter of the Bishop of Lincoln, written
between 1189 and 1192. His title of master of arts indicates that he
had acquired sufficient learning to be entitled to teach. Assuming
that Grosseteste would therefore have been in his early twenties,
Callus 1955 has suggested a birth date around 1168. Around 1195, in a
letter of recommendation to the Bishop of Hereford, William de Vere,
Gerald of Wales commends Grosseteste for his wide reading and skill in
business and legal affairs, medicine, and the liberal arts, and
remarks on his exceptional standards of conduct. Grosseteste appears
as a witness to several of de Vere's charters over the next few years,
but disappears from the historical record after de Vere's death in
1198. He reappears as a papal judge-delegate in Litchfield diocese
before 1216 and in Hereford diocese between 1213 and 1216, acting with
Hugh Foliot, Archdeacon of Shropshire. Grosseteste's name reappears
twice more in legal documents connected with Shropshire before 1227.
For at least part of the years 1208 to 1213, when England was under
papal interdict, Grosseteste was in France, for in a death-bed
conversation reported by the chronicler Matthew Paris he recalls
having seen and heard preaching in France Eustace of Flay, James of
Vitry, Robert of Courson and the exiled Archbishop Steven Langton. In
1225, while still a deacon, Grosseteste was presented by the Bishop of
Lincoln, Hugh of Wells, to the living of Abbotsley; in 1229 he was
made Archdeacon of Leicester and presented with a prebend in Lincoln
Cathedral. In 1229/1230 Grosseteste accepted an invitation to become
the first lecturer to the Oxford Franciscans. In 1235 he was elected
Bishop of Lincoln, a position he occupied until his death in 1253.


 Besides the facts just mentioned, and despite confident statements
about his early life in much of the literature, we know very little
about Grosseteste's life before about 1230. He no doubt was educated
in the liberal arts in England, possibly at Lincoln, and he probably
studied in the late twelfth century at Hereford, then a center of
scientific learning. He is thought to have studied theology in the
early thirteenth century, though exactly where and when is a matter of
disagreement, as is the related question of his relation to the then
nascent Oxford University.


 Scholars have proposed different hypotheses regarding
Grosseteste's life between about 1200 and 1230. According to Daniel
Callus (Callus 1945, 1955, with Crombie 1953 and McEvoy 1982, 2000 in
substantial agreement), from about 1200 Grosseteste probably taught
the arts at Oxford, only to leave Oxford in 1209 to study theology in
France when the Oxford schools closed after some clerics were hanged by
Oxford's mayor and officers. The resolution of the resulting
town-and-gown dispute was delayed by the papal interdict of England
but finally achieved in 1214, when the papal legate sent to England to
negotiate a settlement between the king and pope visited Oxford. The
legate's resolution, known as the Legatine Award, placed the Oxford
masters under the jurisdiction of the Bishop of Lincoln, who was to
appoint as his representative a chancellor of the university. Remarks
by Hugh Sutton, Grosseteste's successor as Bishop of Lincoln, indicate
that Grosseteste had at one time occupied the position of chancellor
at Oxford but had been allowed only to use the title "master of
the schools" and not "chancellor." According to
Callus, Grosseteste probably returned from France in 1214 to become,
in function if not title, Oxford's first chancellor, and lectured on
theology in Oxford's secular schools from this year until
1229/30.


 By contrast, Sir Richard Southern (1986) argued that until 1225
Grosseteste more likely occupied a provincial administrative position,
perhaps supplemented by occasional short periods of teaching, possibly
even at Oxford, among other places. His time in France was in
consequence of the interdict rather than the closure of the Oxford
schools, and was not spent in the study of theology. According to
Southern, Grosseteste's permanent association with Oxford began after
1225, when, having received the prebend of Abbotsley, Grosseteste
probably became a priest and began to lecture in theology. According
to Southern's chronology, he would have become chancellor in the late
1220s.


 Southern's important study had the salutary effect of forcing a
reexamination of the assumptions upon which earlier accounts of
Grosseteste's life rested, but his conclusions remain
contentious. Joseph Goering, after looking closely at the content of
Grosseteste's writings and the documentary evidence, concludes that
"the evidence intimates that he was on the continent along with the
bishop of Hereford and other English Churchmen in exile before 1215,
that he returned to the diocese of Hereford when the interdict was
lifted, and that he continued his diocesan service and his teaching as
a master of arts, at Hereford or elsewhere, into the 1220s" (Goering
1995, 26). Yet Goering thinks that the sources used in Grosseteste's
theological writings, as well as Grosseteste's known ties with
important Parisian thinkers, best support the view that Grosseteste's
study of scholastic theology--a casual and gradual process in his
view--included at least some time studying in Paris in the 1220s,
possibly around 1225 after receiving his substantial prebend in
Abbotsley, which made (and perhaps was intended to make) such a course
of study possible. Goering observes that there is no concrete evidence
that Grosseteste taught at Oxford prior to the late 1220s or that his
teaching in the secular schools at Oxford was in theology rather than
the arts. Grosseteste's association with Oxford and chancellorship
may indeed have only been in the late 1220s as a master of arts--the
fact that he was a master in the lower faculty of arts, not the higher
faculty of theology, would perhaps explain why he was not permitted to
be called chancellor.


More recently James Ginther (Ginther 2000) has argued that
Grosseteste became regent master of theology ca. 1229/30, around the
time he became lecturer to the Oxford Franciscans. Ginther claims that
Grosseteste's *Dictum* 19 in fact records Grosseteste's
inception sermon at Oxford as regent master of theology. Brett Smith
(Smith 2018, n. 34), however, has recently expressed some doubts over
Ginther's claims, and the question of Grosseteste's career before
ca. 1229/30 remains unresolved among scholars.




 In 1229/30 Grosseteste began a formal association with the
Franciscans at Oxford as their first lecturer. The Franciscans had
arrived at Oxford in 1224. Their Minister Provincial, Agnellus of
Pisa, provided this small but growing group with their first school
and requested that Grosseteste lecture to them. Grosseteste's high
regard for the mendicants no doubt played a role in his acceptance of
this request. Some indeed thought that Grosseteste would himself
follow the path of many other eminent scholars of his day and join the
Franciscan order, but this was not to be. Instead, in 1235 he was
elected Bishop of Lincoln. He was not the electors' first choice but
rather a compromise candidate, but he went on to become a powerful and
exacting bishop. Grosseteste's teaching career was over, but he
continued to enjoy close relations with the Franciscans for the rest
of his life. They were members of his episcopal household and he
employed them as assistants and bequeathed his books to them. These
books, kept in the Oxford Franciscan convent library, were to become
an important source for later thinkers' knowledge of Grosseteste's
teachings.


 In 1231, after recovering from serious illness, Grosseteste
resigned all his sources of revenue, save his prebend in Lincoln
cathedral. He went on to compose a series of important theological
works, the most notable being his *Hexaaemeron*, a long
commentary on Genesis 1:1-2:17. A feature of these theological works
is Grosseteste's increasing knowledge of ancient Greek. Just when
Grosseteste began to study Greek is not known, but his studies appear
to have been under way by the early 1230s (see Dionisotti 1988).
Aided by assistants proficient in Greek, Grosseteste became one of the
very few thinkers in the Latin West to know the language. He was not
content, however, to employ his Greek learning simply as an aid in his
theological studies, but he also embarked on important projects of
translation of Greek works into Latin. The first of these projects,
commenced after about 1235, focused on works by the theologian, John
of Damascus. In the late 1230s and early 1240s, Grosseteste turned to
the writings of the Pseudo-Dionysius. He completed a new translation
of the Pseudo-Dionysius's works, to which he added his own original
commentary. Grosseteste had also retained philosophical interests and
in the 1240s turned again to the writings of Aristotle, with whose
works he had engaged as a commentator in the 1220s. He made the first
extant complete Latin translation of the *Nicomachean Ethics*
to circulate in the Latin West, as well as translations of a large
body of accompanying Greek commentary materials, some of which he
supplemented, where they were lacking, with his own original
commentary and notes. Grosseteste also translated, apparently very
late in life, at least substantial parts of Aristotle's *De
caleo* and Simplicius's commentary on it. 


The 1240s also marked an important period of ecclesiastical
activity. Conflict between the papacy and Emperor Frederick II had
led Pope Innocent IV to flee to Lyon in 1244 and relocate the papal
court there until 1251. In hope of resolving this conflict, among
other pressing concerns, Innocent convened the First Council of Lyon
in 1245. Grosseteste was included among the English delegation.
Grosseteste returned to the papal court in 1250. Addressing the pope
and cardinals, he bemoaned the failings of the church, which he
located in its deviation from its pastoral mission. Grosseteste placed
the blame for this state of affairs squarely at the feet of the papal
court, suggesting that if matters continued on their present course
the pope would not be due obedience. In 1253, the last year of his
life, in a famous and angry letter to the pope (letter # 128),
Grosseteste did indeed in no uncertain terms refuse to obey the pope's
instructions to confer a benefice on one of the pope's nephews, whom
he viewed as unfit for the pastoral care. 


Grosseteste died on October 8-9, 1253. His English contemporaries
remembered him as a saintly man. Three attempts were made to have him
canonized, the last in 1307; all failed. 


## 2. Works


Grosseteste's large and rich body of writings includes scientific
works, commentaries on and translations of Aristotle's writings and
works of Greek theology, commentaries on books of the Bible, works in
philosophy and speculative and pastoral theology, collections of
sermons and letters, and a large collection of short theological
writings known as the *Dicta*. Grosseteste also composed some
Anglo-Norman poetry. His works of philosophical interest may be
classified, in modern terms, as follows: 


* *Commentaries on Aristotle*. Many years before Grosseteste
composed his translations of the *Nicomachean Ethics* and
*De caelo,* he had been deeply engaged in the study of
Aristotle's views on scientific knowledge and natural philosophy, and
had composed a commentary on the *Posterior Analytics* and
commenced and made substantial progress on a commentary on the
*Physics.* These are the earliest surviving commentaries on
these works known to have been composed in the Latin West. Extant
manuscripts also contain and attribute to Grosseteste a paraphrase of
the *Prior Analytics*, which may well be genuine, as well as a
commentary on the *Sophistici Elenchi* and another commentary
on the *Physics*, both of which appear to be inauthentic. The
commentary on the *Posterior Analytics* appears to have been
written in the 1220s and is an important source for Grosseteste's
epistemological views. The authentic commentary on the *Physics* appears to have been assembled by a later editor or
editors from notes Grosseteste had written in his copy of the
*Physics* as the basis of a commentary along the lines of the
commentary on the *Posterior Analytics*. Though incomplete,
these notes comprise a substantial and coherent work, the bulk of
which was also probably written in the 1220s, though what appear to be
some additions to the body of the work in which Averroes's long commentary on the *Physics* is
used probably date from the 1230s (see Lewis 2003). This work is an
important source for Grosseteste's views on numerous topics in natural
philosophy.
* *Philosophical works*. Grosseteste composed a number of short
philosophical works. *On Light* (*De luce*) his minor
masterpiece, develops his so-called light metaphysics; it appears to
be the object of cross-references in his commentaries on Aristotle and
thus written prior to them. Closely related to *On Light* is a
short work *On Bodily Movement and Light* (*De motu
corporali et luce*). Other short philosophical works are *On
Potency and Act* (*De potentia et actu*), *On the Halt
of Causes* (*De statu causarum*), *On the Subsistence of
a Thing* (*De subsistentia rei*), and *On the Truth of
the Proposition* (*De veritate propositionis*). *On the
Finitude of Movement and Time* (*De finitate motus et
temporis*) (a longer version of which is appended to the
commentary on the *Physics*) attacks Aristotle's arguments for
the infinitude of past time and movement; it was probably written in the
1230s
* *Philosophical-theological works*. The most important and
substantial of these works is *On Free Decision* (*De libero
arbitrio*), a relatively long work in two versions that is
concerned with arguments against the existence of free decision
(*liberum arbitrium*)--especially those based on God's
foreknowledge--and with the nature of free decision itself. Closely
related are the shorter works *On Truth* (*De veritate*)
and *On God's Knowledge* (*De scientia Dei*). These
works all appear to date from after ca. 1225, and more probably from the late 1220s or
beginning of the 1230s. A short work, *On the Order of the
Emanation of Caused Things from God* (*De ordine emamandi
causatorum a Deo*), attacks the argument that an eternal being can
only create eternal creatures. A long letter to Adam Rufus (= Adam of Exeter), the first
in Grosseteste's letter collection, explains how God is form of all
things and investigates the relation of body and soul and the location
of angels. In the manuscripts this letter is often divided into two
distinct works, *On the Unique Form of all Things* (*De
unica forma omnium*) and *On the Intelligences* (*De
intelligentiis*).
* *Scientific works*. Grosseteste's scientific writings include
what appear to be his earliest works, which possibly were written
during the first two decades of the thirteenth century: *On the Liberal
Arts* (*De artibus liberalibus*), *On the Generation of
Sounds* (*De generatione sonorum*), and *On the
Sphere* (*De sphaera*), an outline of astronomy. Later in the
thirteenth century, Grosseteste wrote a number of short
scientific works including *On Comets* (*De cometis*), *On Lines, Angles and Figures* (*De
lineis, angulis et figuris*), *On the Nature of Places*
(*De natura locorum*), *On the Rainbow* (*De
iride*), *On Color*, (*De colore*), *On Local
Differences* (*De diferentiis localibus*), and *On the Movement of the Supercelestial Bodies* (*De motu supercaelestium*). (For an outline of the
content of many of these works see Dales 1961 and Panti 2001. The works *On the Heat of the Sun* (*De calore solis*), *On the Tides* (*De fluxu et refluxu maris*), *On the Generation of the Stars* (*De generatione stellarum*), and *On the Impressions of the Air* (*De impressionibus aeris*), first edited in Baur 1912, are probably inauthentic. In the most recent discussion of the dating of Grosseteste's scientific works, Panti 2013 argues that the first two of these works were probably written by Adam of Exeter, the addressee of Grosseteste's first letter.).
* *Theological works containing some material of philosophical
interest*. Though not as expressly philosophical as the works
noted above, *On the Cessation of the Ceremonial Laws* (*De
cessatione legalium*), *On the Ten Commandments* (*De
decem mandatis*) and the *Hexaaemeron*, all
substantial works written in the 1230s, contain some material of
interest to the philosopher. *On the Cessation of the Ceremonial
Laws* argues that the Incarnation would have occurred even without
the fall, and touches on the nature of human happiness and natural
law. *On the Ten Commandents* provides some insight into
Grosseteste's thinking about ethics, while the *Hexaaemeron*, his theological masterpiece, considers in
detail the problem of the eternity of the world. Material of
philosophical interest is also to be found in the *Dicta*, some
of Grosseteste's later sermons (notably the sermon *Ecclesia sancta
celebrat* where he outlines an account of human nature) and his
commentaries on the Pseudo-Dionysius.


 In the present article the focus is on Grosseteste's thought in
works from the first three categories.


## 3. Sources


 The most fundamental influence on Grosseteste's thought was
St. Augustine, from whom Grosseteste drew a Neoplatonic outlook. Yet
Grosseteste was also strongly influenced by the Latin translations of
Greek and Arabic philosophical and scientific writings that had poured
into the Latin West in his lifetime, notably the thought of such
thinkers as Aristotle, Avicenna and Averroes (whose works Grosseteste
was one of the first to use; see Gauthier 1982). These influences often pull him in
different directions and his thought can take on an eclectic
character. In general, however, he attempts to subordinate Greek and
Arabic philosophical learning, when necessary, to his Augustinian
Neoplatonism.


 Although there is little doubt that Grosseteste was to some extent
influenced by his contemporaries, his writings show little concern to
engage in debate with them, in contrast with the practice of his
contemporaries in Paris. This perhaps reflects a provincial origin
of Grosseteste's works, but may also reflect a conservative preference
to engage with the ideas of the great thinkers of the recent and more
remote Latin and Greek traditions. The Christian
influences on his philosophical writings were in particular Boethius,
St. Anselm, and St. Bernard of Clairvaux, in addition to Augustine.
Grosseteste also made frequent use of the writings of Cicero and
Seneca. Later in life, in the 1230s and 40s, the influence of Greek
thinkers such as John of Damascus, St. Basil and the Pseudo-Dionysius
is prominent in his theological writings.


 Grosseteste's *Tabula* (Rosemann 1995) provides an unusual
insight into his sources. This work is a topical concordance in which
Grosseteste lists readings, Christian and non-Christian, on a wide
range of topics of theological and philosophical interest.
Grosseteste associated with each topic a sign, which, written in his
own manuscript books, allowed him quick access to the material in
question.


## 4. The Metaphysics of Light


 If a single leitmotif runs through Grosseteste's works, it is that
of light. The notion of light occupies a prominent place in
Grosseteste's commentaries on the Bible, in his account of sense
perception and the relation of body and soul, in his illuminationist
theory of knowledge, in his account of the origin and nature of the
physical world, and, of course, in his writings on optics. Just how
tightly associated Grosseteste took the notions of light employed in
such different contexts to be is unclear. From a philosophical point
of view, which will be the focus here, undoubtedly his use of the
notion of light in his account of the basic structure and origin of
the physical universe is of fundamental importance and the greatest
originality.


 Grosseteste's so-called metaphysics of light rests on a
hylomorphic (matter-form) account of the metaphysical makeup of
bodies. On this basis Grosseteste explains the generation and nature
of the cosmos. Grosseteste also interprets aspects of Aristotle's
natural philosophy in terms of this theory. He sets out this theory
most fully in *On Light*, but elements of it are present also in
his commentaries on the *Posterior Analytics* and *Physics*, in *On Bodily Movement and Light*, and in his
commentary on *Ecclesiasticus* 43: 1-5, also known as *On the
Operations of the Sun*. 


Grosseteste treats bodies as composites of a first or prime matter
and a corresponding first form. This form, termed
"corporeity," is the form in virtue of which something is
a body. Grosseteste takes bodies to be more or less metaphysically
simple depending on whether, in addition to corporeity, they include
other substantial forms. Thus, in *On Light* he holds the
firmament or outermost heavenly sphere to be the most simple body, as
it is composed simply of first matter and first form, but in his
commentary on the *Physics* he speaks of the element fire as
having in addition to first form the substantial form of fire.


 Grosseteste's originality lay not in presenting a doctrine of
first form and first matter. Aristotle was standardly understood to
propound a notion of first or prime matter, and the notion of a first
form may be found in texts of Neoplatonic inspiration, such as the
*Fons vitae* of Avicebron (see McEvoy 1982, 158-162). What
appears to be original, however, is Grosseteste's identification of
first form with light (*lux*). *On Light* opens with an
argument for this identification. Grosseteste asserts that first form
and first matter are in themselves simple substances. Yet first form,
corporeity, necessarily results in the extension of matter into three
dimensions, thereby yielding a quantified body. A simple form without
dimension could only have this effect, however, if it instantaneously
multiplied and diffused itself in all directions, thereby extending
matter along with its diffusion of itself. But these are
characteristic features of light, for light is essentially
self-multiplicative and self-diffusive, a sphere of light being
instantaneously generated from a point of light. Thus, Grosseteste
concludes that light is in fact the first form.


 On the basis of this theory Grosseteste developed a cosmogony and
cosmology. He saw in the metaphysics of light insight
into God's creation of the physical universe and an explanation of why
it took the form it did. At the beginning of time, Grosseteste
asserts, God created first form or light in first matter. First form
and first matter are in themselves indivisible and simple, and
according to Grosseteste the finite multiplication of a simple cannot
generate an item with size (*quantum*). But, he thinks, the
infinite multiplication of a simple will generate a finite
*quantum*. Thus, through the infinite multiplication of first
form in first matter extended bodies, and thus the physical universe,
were produced. To account for bodies of different sizes, Grosseteste
posits that there are infinities of different sizes (see below) that
stand in different ratios, numerical and non-numerical, to each
other. Thus, "light by the infinite multiplication of itself extends
matter into larger and smaller finite dimensions that stand to one
another in all ratios, numerical and non-numerical" (Lewis 2013,
241-242).


Grosseteste employs the notion of light to explain the genesis of
the Aristotelian cosmos as a system of nested celestial spheres
surrounding the four sublunary or elemental spheres. According to
Grosseteste, the infinite self-multiplication of the initial point of
light extended the first matter it informed into a spherical form,
since light diffuses itself spherically. The outermost parts of the
matter of the sphere thereby generated, unlike the parts of the matter
below them, were maximally extended and rarefied and formed the
outermost (or first) sphere, the firmament. Yet because light is
essentially self-multiplicative, the light in this outermost sphere
continued to multiply itself, only now it did so back inwards toward
the center from all parts of the outermost sphere, since it had
already diffused itself outward as far as it possibly could. And since
light, being a substantial form, cannot exist apart from matter, this
inwardly directed light drew with itself what Grosseteste calls the
spirituality of the matter of the outermost sphere, and thus
*lumen*, a body comprised of light and the
spirituality of this matter, proceeded inwards. Moving inwards,
*lumen* concentrated the matter existing below the outermost
sphere, leaving in its wake below the outermost sphere a second sphere
comprised of matter whose parts were rarefied as much as they could
be. This sphere in turn generated *lumen*, which moving inwards
further concentrated the matter below it and rarefied the outermost
parts of this matter so as to produce the third sphere. The repetition
of this process gave rise to the nine celestial spheres, each sphere
being comprised of matter whose parts were incapable of further
rarefaction.


The lowest celestial sphere, the lunar sphere, also generated
*lumen*, which moved inwards and further concentrated the matter
below this sphere. But since this *lumen* lacked enough power to
fully disperse the outermost parts of this matter below the lunar
sphere, it produced a sphere comprised of incompletely dispersed
matter, the sphere of fire. Likewise, fire generated *lumen*,
producing below it yet another sphere of incompletely dispersed
matter, the sphere of air. This process continued, giving rise in turn
to the spheres of water and earth, the latter being comprised of the
most concentrated and dense matter. Because the matter of these four
elemental spheres was not fully dispersed, it remained capable of
being concentrated and dispersed, and for this reason the elements,
unlike the celestial spheres, are capable of alteration, growth,
generation and corruption.


Grosseteste also employs this theory of light as part of his
explanation of the nature of the heavenly movements. He explains that
the heavenly bodies can only move with a circular movement because the
*lumen* in them is incapable of rarefaction or condensation, and as
a result cannot incline the parts of their matter upward (to rarefy
them) or downward (so as to condense them). Indeed, the heavenly
spheres can only receive movement "from an intellective motive
power," that is, an intelligence or angel, "that in
incorporeally casting its mental gaze back over itself rotates the
spheres with a corporeal revolution" (Lewis 2013, 246). Because
the elements, on the other hand, can be rarefied and condensed, they
can incline the *lumen* in themselves away from the center of the
universe, so as to rarefy it, or toward the center so as to condense
it, and this accounts for their natural capacity to move up and
down.


Although the metaphysics of light is fundamentally non-Aristotelian
in nature, Grosseteste clearly was concerned to use it to explain many
of the features of the Aristotelian cosmos--the system of
nested spheres, the distinction between the movement of celestial and
sublunary bodies, and so forth. In like manner, in his commentary on
the *Physics* he interprets fundamental ideas in Aristotle's
natural philosophy in terms of the light metaphysics, explaining
Aristotle's theory of potentiality in terms of the replicability of
form and holding that every bodily species comes to be by "the
greater or lesser replication of the simple first bodily form,"
light (Dales 1963a, 17). Likewise, Aristotle's three principles:
form, privation and the underlying subject, are interpreted as the
first form light, the impurity of light in things, and first matter
respectively. In *On Bodily Movement and Light*, Grosseteste
identifies nature, conceived by Aristotle as an internal source of
movement and rest, with the first form, light, and claims that all kinds
of bodily change are the "multiplicative force" of the first
bodily form, light (Baur 1912, 92).


## 5. Infinity, Continuity, and Measurement


 Grosseteste appears to have been the first in the Latin West to
propose a doctrine of unequal infinities. In *On Light* he holds
that there are infinite numbers that differ in size: "the sum of all
numbers, both odd and even, is infinite and is greater than the sum of
all the even numbers, even though this too is infinite, for it exceeds it
by the sum of all the odd numbers" (Lewis 2013, 241). According to
Grosseteste, infinite numbers can stand to one another not only in
every numerical ratio, but also in every non-numerical ratio
(Grosseteste has in mind the ratio of the infinite numbers of points
contained in incommensurable lines). He clearly thinks lines and other
continua *contain* different-sized infinities of points or
indivisibles, viewed as dimensionless simples. But he also thinks
points are *parts* of lines, and more generally, that
indivisibles serve to make up continua. He is aware that Aristotle
seems to reject this view and hold that magnitudes only have
magnitudes as their parts, but he claims in *On Light* that the
term "part" has a range of meanings depending on which
mathematical relationship of parts to wholes is in
question. Aristotle, he asserts, means by "part" in
connection with continua an *aliquot* part and is concerned only
to deny that continua are composed of indivisibles as aliquot
parts. But this denial does not entail that indivisibles are not parts
standing in a different mathematical relationship to the wholes to
which they belong. According to *On Light*, a point is a part of
a line in the sense that it is in a line "an infinite number of times,
and does not diminish the line when substracted from it a finite
number of times" (Lewis 2013, 242). Grosseteste says little about the
ordering of indivisibles in continua but mentions without criticism
Aristotle's view that indivisibles in continua must be densely or
"mediately" ordered, so that between any two is yet another, a view
attributed to him by Albert the Great and Thomas Bradwardine (see
Lewis 2005).


 Grosseteste's theory of unequal infinities served as the basis of
a theory of how God measured the world he created. Grosseteste takes
up measurement in his commentary on the *Physics* (Dales 1963a,
90-95), in one of the earliest theoretical discussions of measurement
in the middle ages. He points out that human measurement of time
involves taking some recurring movement--say, the daily movement of
the heaven--and stipulating its duration to be a unit of
measurement. In the same way, the magnitude of some body is taken as a
unit of the measurement of spatial magnitude. Measurement of this
sort, Grosseteste holds, is inherently relative in nature. To say that
an event lasts for a day, for example, is simply to relate its
duration to the duration of the movement of the heavens. But Grosseteste
thought that this mode of measurement would not suffice for God, who,
as he frequently mentions, "has disposed all things in number, weight
and measure" (*Wisdom* 11: 21). God's creative activity requires
that he create bodies with a definite magnitude and movements with a
definite duration, and this requires that there be a non-relative
measure intrinsic to magnitudes and durations. According to
Grosseteste, this measure is provided by the different-sized
infinities of indivisibles comprising spatial and temporal
magnitudes. Grosseteste points out in his commentary on the
*Physics* that were only a single line to exist, it would not be
possible for us to measure its magnitude, and yet God could do so by
counting the infinite number of points that comprise its
magnitude. Only God can measure in this way, for only to him is the
infinite finite, an allusion to Augustine's teaching in *The City of
God* 20.19 that God alone can embrace an infinity in his mind.


## 6. Creation, Eternity, Time and Being


As a Christian, Grosseteste believed that God created the world
with a beginning; indeed, he thought, as some sketchy arguments in the
*Hexaaemeron* 1.9.7 indicate, that the beginning of the
world could be proved. But his primary contribution to the medieval
debate over the beginning of the world was his interpretation and
refutation of Aristotle's arguments in *Physics* 8 for a
beginningless or "eternal" world (see Dales 1986). In this connection
Grosseteste was at odds with some of his early thirteenth-century
contemporaries, such as Alexander of Hales, who thought that Aristotle did not mean to deny the
beginning of the world but only that it had a *natural*beginning. Let those who adopt such an interpretation, he writes
in his *Hexaemeron*, "not deceive themselves and pointlessly try
to make a Catholic of Aristotle, thereby wasting their time and mental
powers and, in making a Catholic of Aristotle, make heretics of
themselves" (Dales and Gieben 1982, 61)


 Grosseteste takes up Aristotle's arguments for a beginningless
world in his *Hexaaemeron* and, in greater detail, in the
closely related treatise *On the Finitude of Movement and Time*.
In both works he holds that Aristotle was led to propose his erroneous
arguments as a result of a failure to adequately grasp simple
eternity. Grosseteste is prepared to grant that Aristotle and other
philosophers proved that God exists and is unchangeable and
non-temporal and that they indeed had some grasp of simple
eternity. Even so, their incomplete understanding of simple eternity
meant that they did not really understand what they proved. This lack
of understanding was due to a disordering of their *affectus* or
will, rather than of their *aspectus* or reason. This distinction
between *affectus* and *aspectus*, which appears to derive
from Augustine, is characteristic of Grosseteste's thought (see Smith 2018). According
to Grosseteste, genuine understanding requires that one's will or
desires be directed away from the sensible world to the unchanging
eternal realm, but Aristotle and the other philosophers, being
preoccupied with the sensible world, could not achieve true
understanding.


Simple eternity is God's eternity, the
non-temporal mode of being enjoyed by God. Like
Augustine before him in *Confessions* 12.40, Grosseteste thinks we can speak
of eternity as before time and of time as after eternity, provided we
bear in mind that the terms "before" and
"after" are in this connection employed in non-temporal
senses. According to Grosseteste, if Aristotle had more fully grasped
simple eternity he would have realized his arguments for the eternity
of the world rest on a failure to recognize non-temporal notions of
before and after. Aristotle, he thinks, assumes in two of his
arguments for the eternity of the world that a first movement would have
to have been preceded by a potentiality for this movement and thus by
time. But since, according to Aristotle, time requires movement and a
potentiality for something can only be exercised through a movement,
there follows the absurdity that the first movement would not be the
first movement. Thus time and movement must be without a beginning.
Grosseteste objects that although the first movement exists after not
existing and that there was indeed a potential for that movement before
it, in this context "was" and "before"
refer to the relation of eternity to time and are used in a
non-temporal sense. The first movement was preceded by a potentiality
for itself, not in time, but in God's eternity, and the actualization
of this potentiality involves no movement or change in God. As for
Aristotle's third argument that there cannot be a first instant, hence
nor a beginning of time or change, because an instant is a link
between past and future, Grosseteste responds that this conception of
an instant will appeal only to someone already committed to the
eternity of time and change.


 According to Grosseteste, the notion of eternity is key also to
understanding the nature of time. In his commentary on the
*Physics* he takes Aristotle's conception of time as a number of
change in respect of before and after to be the result of a
superficial discussion, adequate as far as the natural philosopher is
concerned but inadequate as an account of time's true essence, an
inadequacy, he thinks, Augustine had also seen. But Grosseteste is not
attracted to what he takes to be Augustine's subjectivist conception
of time and instead seeks an account of the true essence of time as an
objective phenomenon.


 According to Grosseteste, time is "the privation of the
*at-once* of eternity from the totality of being" (Dales 1963a,
96). He means that for there to be time there must be items whose
existence does not adhere as a whole, as he puts it, with the
*at-once* of eternity, that is, whose existence is not
instantaneous. Eternity, is, as it were, a fixed point subject to a
continuous succession of the adherences of instantaneous bits of the
totality of existence, one bit adhering to eternity only continuously
to be replaced by another; this continuous replacement constitutes the
flow of time. Grosseteste defines the instant, by which he means the
now, as this adherence of being with the *at-once* of eternity,
and likewise defines past and future in terms of this adherence. He
realizes that his use of tenses in his explanations of these notions
renders them ultimately circular, but asks that he not be criticized
"for making these differences known in terms, as it were, of
themselves, for it does not come to mind, or does not do so easily,
how they could otherwise be made known" (Dales 1963a, 98).


 
Grosseteste's account of time appears to be closely related to his
conception of existence, as presented in his commentaries on the
*Posterior Analytics* and *Physics* and in *On
Truth* (Rossi 1981, 290-291; Dales 1963a, 7; Baur 1912,
141; see also Lewis 2009). Grosseteste holds that a created thing's
existence just is its dependence on God. Thus, a thing does not
depend on God for its existence; its dependence on God *is* its
existence. Grosseteste appears to equate this relation of dependence
with the relation of adherence to the  *at-once* of eternity
mentioned in his account of time. He remarks that "something no
more partakes of actual existence except insofar as it adheres to the
first being that is all at once" (Dales 1963a, 96-97). He
does not seem to realize that the relata of the relation of adherence
in his account of time and of the relation of dependence in his
account of being are different: in his account of time it is an
instantaneous bit of a thing's *existence* that adheres, while
in his account of existence it is the thing itself that is dependent
and existence is itself treated as a relation, not as the term of a
relation.


## 7. Divine Foreknowledge and Human Freedom


*On Free Decision* is one of Grosseteste's most influential
and substantial philosophical works. Its first half is largely devoted
to the problem of reconciling God's knowledge of the future with human
freedom. Much of the importance of this discussion resides in the
theory of modality that Grosseteste develops, but it is also of
importance for the argument Grosseteste presents for the
incompatibility of God's knowledge of the future and future
contingency. Grosseteste correctly takes himself to be presenting a
different argument, and different solution, from those found in
Boethius and Anselm, who had written two of the most important earlier
discussions of the issue. 


 Grosseteste presents this argument as follows: "Everything known
by God is or was or will be; *a* is known by God (let *a* be a future
contingent); so *a* is or was or will be. But *a* neither is nor
was; so it will be. Each of the premises is clearly
necessary, as is the inference. So the conclusion is not just true but also
necessary, for only what is necessary follows from things that are necessary" (Lewis 2017, 111). The argument is in two parts: A sound argument without modal premises is presented for the conclusion that an event will
occur. It is then claimed that its premises are necessary, and thus,
by the principle that entailment transmits necessity from premises to
conclusion, that its conclusion is necessary too. In his discussion of
this argument Grosseteste focuses on premises formulated in terms of
God's knowledge, but he clearly thinks that a range of arguments
having the same form can be constructed, employing in their initial
part not only premises about God's knowledge, but also premises
formulated in terms of prophecy or even just past-tensed truths of the
form "It was the case that A will exist." 


 Grosseteste's appeal to the principle that entailment transmits
necessity from the premises to the conclusions of a valid inference is
a striking feature of the kind of argument he considers. This
principle forms the focus of much of Grosseteste's discussion of the
argument: "It would seem," he notes, "that the only reply that we can give to the [arguments] stated above ... is to say that what is contingent does indeed follow from things that are necessary" (Lewis 2017,
129). But in the final analysis Grossetete does not reject the
principle; he holds that entailment does indeed transmit necessity
from premises to conclusion: "By syllogistic inference, then, what is necessary follows from necessary antecedents with the kind of necessity possessed by the antecedents, and the conclusion, like the antecedents, has truth that cannot cease in the future and from which it cannot be altered." (Lewis 2017, 139).


 Grosseteste's response to such arguments is to grant that they in
fact are sound and do indeed prove the necessity of true propositions
about future acts. But he challenges the further conclusion drawn
from them that if a proposition about a future act is necessary in the
sense proved by such arguments, the act cannot really be a free
act. Instead, Grosseteste takes the kind of necessity involved in such
arguments to be compatible with freedom. His strategy is to hold that
the freedom of future acts is incompatible only with a different kind
of necessity, and that such arguments fail when formulated in terms of
this conception of necessity, since their premises and conclusions are
contingent in the correlative sense of contingency.


 Grosseteste's response to the conflict between divine
foreknowledge and free decision and related arguments therefore has
two parts: first, the claim that there is a distinct family of modal
notions in respect of which future events and true propositions about
them may be contingent; second, the claim that freedom requires only
this kind of contingency. Unfortunately Grosseteste has little to say
in support of this second claim, but his introduction of a distinct
family of modal notions is of philosophical interest in its own right,
as it marks an important stage in the development of modal theory.


## 8. Modality and God's Power


When Grosseteste wrote *On Free Decision* modal concepts were
typically understood in terms of the notion of change and thus of
time. Thus, Grosseteste speaks of a necessary proposition, in this
sense, as one that is true and cannot *become* false, or as one
whose truth is unable to *cease* to be. A contingent proposition
can change its truth value; a possible proposition, if false, can
become true, and an impossible proposition is false and cannot become
true. Conceptions of modality along these lines were sometimes
described as *per accidens* conceptions, since in many cases a
proposition's modal status could change with the passage of time; its
modal status, as it were, happens to or is incidental to it
(*accidit*). "Caesar crossed the Rubicon," for
example, was once false and not necessary, but became true and
necessary, because unable to become false, after Caesar crossed the
Rubicon. Indeed, true propositions about the past were the standard
examples of propositions necessary in the sense that their truth
cannot cease. 


Grosseteste holds that true propositions about the present may well
be contingent on this conception of contingency, since they can become
false; he gives "Socrates is pale" as an example (Lewis
2017, 41). But he holds that all true propositions about the future
are necessary. It might be thought that this is incorrect, since it
is not hard to think of cases in which a true proposition about the
future becomes false after the occurrence of an event it predicts.
But closer inspection reveals that Grosseteste thinks that true
propositions about the future are necessary because they cannot become
false *prior* to the obtaining of the state of affairs they are
about; he has a limited unchangeability of truth in mind.


Grosseteste does not reject this conception of *per accidens*
modalities. Rather, he introduces another family of modal notions
unconnected to considerations of time or change, a family of
non-temporal modal notions. And he holds that many true propositions
about the future, including those about future free acts, are
contingent in the sense of contingency belonging to this family, as
indeed also are true propositions regarding God's knowledge of those
acts, past prophecies of them or even statements to the effect that it
was the case that the acts would occur. Ideas along these lines, we
may note, were not original to Grosseteste; they are *implicit*in some of his predecessors, such as Peter Lombard, whom
Grosseteste cites. But they, unlike Grosseteste, had not attempted to
work out in any detail a *theory* of modality severing a link
with considerations of time and change (the twelfth-century thinker,
Peter Abelard, is an exception, but his theory of non-temporal
modality, which takes as its central notion that of a thing's nature,
is very different from Grosseteste's and had little
influence). Thinkers after Grosseteste, such as Duns Scotus, developed
accounts of non-temporal modality in even more detail that share
elements found in Grosseteste's account and were perhaps influenced by
it (see Lewis 1996).


The guiding idea behind Grosseteste's approach to a notion of
non-temporal contingency is that even if a proposition such as
"Antichrist will exist" (to use his standard example of a
true, future contingent proposition) is true now and cannot become
false until Antichrist comes into existence, the world might
nevertheless have been such that "Antichrist will exist"
was never true. A present-day thinker might spell this idea out in
terms of alternative possible worlds, but Grosseteste spells it out in
terms of the notion of a proposition's eternal power or capacity for truth or
falsity without beginning, and grounds such powers ultimately in God's
eternal power to know or will propositions.


Grosseteste's discussion of non-temporal modalities and their
relation to God's power is most fully set out in the earlier
recension of *On Free Decision*. Focusing on necessity, he
writes that "something is called necessary in that it has no
capacity, either not to be, or not to have been, or not to be going to
be. [The *dictum*] 'that two and three are five' is
necessary in this sense, because it has no capacity not to be true in
the present, or in the future, or in the past, or ever, be it with or
without a beginning" (Lewis 2017, 39,41). He goes on to describe
the corresponding notion of contingency as a matter of a
proposition's having "a capacity for being true and being
false without a beginning." What is necessary in this sense
utterly lacks a power to be false. What is contingent, in the
corresponding sense, could have had from the beginning a different
truth-value, though it may well lack a power to change its truth-value
from that which it actually has. Grosseteste holds that this kind of
contingency of propositions about future events or things implies that
the things or events the proposition is about may themselves be called
contingent, and that this kind of contingency is sufficient for the
freedom of our future acts.


Much of Grosseteste's account of modality is concerned with
difficulties posed by the notion of the eternal power of a proposition
to be true or false without beginning. He seems to hold such powers to
be possessed not in time, but in eternity. He notes that God too has
eternal powers, namely to know or will without beginning, and that the
difficulties confronting the eternal powers of propositions also
confront the eternal powers of God. In fact, Grosseteste explains the
eternal powers of propositions in terms of God's eternal powers
to know and will propositions, effectively grounding non-temporal
modality in God's powers or lack thereof (in the case of
necessity and impossibility). He notes, for example, that "the
eternal capacity for [the *dictum*] 'that Antichrist was
going to exist' to have had truth and not to have had truth
without a beginning is nothing but the capacity of God by which God
was able from eternity and without a beginning to will or not to will
that Antichrist will exist, or to know or not to know that Antichrist
will exist" (Lewis 2017, 55).


 The difficulties facing the notion of eternal powers stem from the
idea that there are unexercised but nonetheless genuine eternal
powers, as Grosseteste's account of non-temporal contingency seems to
require. Put in terms of God's powers to know or will, one problem is
what it could mean to say that God *could have* not known or
willed what he in fact knows or wills (or the converse), as is
implied, Grosseteste thinks, by the doctrine that God has the power to
not know or not will what he knows or wills. For "could
have" expresses the priority of power to act, the idea that
prior to God's willing that p, he had a power not to will that p. But
God is not in time and thus "could have" cannot express a
temporal priority of God's power to its act. Grosseteste's solution
to this problem is to hold that it expresses a so-called causal
priority, a notion he drew from Eriugena (Grosseteste prefers not to
call it a natural priority since there is no distinction of natures
involved in God's power and act) (see Lewis 1996).


 The notion of unexercised eternal powers also faces the difficulty
that unexercised powers appear to be powers for future acts and, if
genuine, can be exercised in the future. But how could a timeless
being, as God is, exercise at a future time his power to know or will
what he in fact does not know or will; indeed, are not such powers
described as powers to know or will *without beginning*? Such
an attribution of power to God therefore seems to be empty
(*frustra*). The problem Grosseteste confronts here is central
to anyone who, like him, takes God to be timeless and yet to have
powers to do what he does not do, and it is to Grosseteste's credit
that he puts the problem squarely on the table. His solution appeals
to the idea that God's powers to know or will are rational powers,
powers that can be exercised in more than one way (the concept of a
rational power is drawn from Aristotle). Thus the power to know that
*p* is the same as the power to not-know that *p*. But
given such a conception of power, if God knows that *p*, then
his power to not-know that *p* is *ipso facto*
exercised, since it is the very same power as the power to know that
*p*. So there are no unexercised powers in God after
all. Thomas Bradwardine noted in criticism of this account that a more
plausible requirement on exercisability is that if an agent has a
power to know that *p* and does not know that *p*, then
he can exercise that power by knowing that *p*. Grosseteste
has no reply to this objection; its answer would require a more
thoroughgoing examination of the relation of power to time and change
than Grosseteste gives (see Lewis 1996).


## 9. Free Decision and Freedom of the Will


Early thirteenth-century accounts of human action and the freedom
it involves focus on the notion of free decision (*liberum
arbitrium*). This term, a legacy of Roman law and patristic
thinkers, has no present-day counterpart, and even to thinkers in
Grosseteste's day its sense was unclear and stood in need of
determination. But if the notion of free decision itself is now of
merely antiquarian interest, accounts of free decision are nonetheless
important for the insight they provide into their authors'
understanding of human action and freedom, issues of perennial
philosophical concern. (On Grosseteste's theory of free decision see Lewis 2013, 2017, and Pickave 2017.)


The expression "free decision" was understood to refer
not only, as its grammar as a concrete term suggests, to a certain
kind of act, but also to the capacity or capacities whose exercise
such an act involves. The word "decision" was standardly
taken to involve a reference to reason and "free" a
reference to the will. Thus, it was often asked whether "free
decision" refers to an act of reason or of the will, and whether
the capacities that such an act involves are reason or will, either
alone or in combination, or possibly other capacities besides
these.


 According to Grosseteste in *On Free Decision*, "free
decision" in its concrete usage refers to a decision, a certain
kind of act of reason. This act, like any other act of reason, is not
itself free, but is said to be free in a derivative sense because it
is an act providing direction to the will, whose acts are free. (Talk
of will and reason or their acts as free or not is common in medieval
thinkers, but is perhaps a mere manner of speaking, when what is
intended is that the agent's exercise of reason or will is done freely
or not.) Reason has the task of distinguishing between good and bad,
better and worse, and of proposing to the will what it should choose
or reject. The will by nature chooses or rejects after receiving such
a directive from reason, but is free not to implement reason's
decision and choose or reject otherwise than reason has
pronounced. This freedom is why the decision is, in a derivative
sense, said to be a free decision. In proposing this view,
Grosseteste indicates that he takes the choices made by the will not
to be psychologically determined by reason: reason provides the will
with advice, not necessity. 


 Grosseteste takes the capacities underlying free decision to be
reason and will, which he identifies with *aspectus* and
*affectus* respectively. He holds, perhaps under the influence of the Pseudo-Augustinian *De spiritu et anima*'s teaching of the simplicity of the soul, that these
capacities are at root one, but this one capacity can be exercised in
one way through a decision, and in another through a choice.


 Since Grosseteste holds that a decision is said to be free because
it provides direction to the free will, as we might expect he takes
the freedom of decision (*libertas arbitrii*) to be the freedom
of the will itself. But what, exactly, is the nature of this freedom?
It is common to think that the freedom of the will is the will's
capacity to will alternatives, or considered *post factum*, to
have willed otherwise than it did. Grosseteste and his contemporaries
speak in this connection of a *flexibilitas* or *vertibilitas* of the will. The importance of Grosseteste's account
of the freedom of the will lies in the fact he is one of the few
thinkers in his day to hold that the freedom of the will is indeed to
be defined as a capacity to will alternatives. Many of his most
important contemporaries, in contrast, explicitly reject such a
conception. They understand the pertinent alternatives to be moral
good and evil, and point out the standard teaching that some agents
with freedom of the will (God and the angels confirmed in good) simply
cannot will moral evil, whereas others (Satan and his cohorts) cannot
will moral good. Thus, they conclude that the freedom of the will
cannot be defined as a capacity to turn between alternatives, and
instead present alternative definitions of freedom--some, for
example, define the will's freedom as its inability to be compelled.
Grosseteste saw that their rejection of a definition of freedom in
terms of a capacity to will alternatives rested on the assumption that
the alternatives in question must be moral good and evil. He rejected
this assumption and instead held that the freedom of the will is the
will's capacity to turn between what he calls "bare opposites
considered in themselves." Though Grosseteste provides little detail
about the notion of a "bare opposite", it is clearly to be understood
by reference to his view, as propounded in *On Free Decision*,
that the moral goodness or evil of an act is a matter of its relation
to God's will. Considered in themselves in independence of their
relation to God's will, as "bare" acts, acts are morally
indifferent. 


 Thus, the freedom of the will is the will's capacity to will, or
more particularly, choose alternatives in the sense of morally
indifferent alternatives. This is not to say that the objects of
choice are considered as neither good nor bad; Grosseteste believes
that one can only choose what one takes to be good. Rather, the notion
of goodness involved in the choice of bare opposites is not the notion
of moral goodness. Grosseteste describes it as natural goodness, but
says very little about it. Given his views about the
non-determination of the will by reason, he would seem to think that
an agent who is choosing among natural goods can choose contrary to
reason's dictate as to which of these is the best option or the one
that should be chosen, or can at least refrain from making a choice in line with reason's dictate.


 According to Grosseteste, this capacity to choose morally
indifferent alternatives underlies our capacity for moral choice when
it is present, though he provides little explanation of how it does
so. He holds that human beings cannot choose moral good without the
assistance of God's grace, but he does not discuss just how that
assistance, combined with the aforementioned freedom, helps to make
moral choice possible. Possibly he thinks that God's grace makes it
possible for the fact that something is willed by God, and thus is
morally good, to serve as a reason one has for choosing it. In any
event, he makes it clear that the capacity to choose moral good is not
intrinsic to possession of reason and will; otherwise the aid of grace
would not be needed. Likewise, the capacity to choose moral evil is
made possible by a feature that is not intrinsic to possession of
reason and will, since God, who has reason and will, cannot choose
moral evil. Rather, in ways not explained, the creature's capacity to
choose moral evil is due to the fact, as Augustine too had held, that
the creature is created from nothing, an inherent and unavoidable
defect in any creature. In those confirmed in good, however, God has
so made it that this capacity cannot be exercised, and so they are
incapable of making an evil moral choice.


It is now common to distinguish accounts of free will that take some sort of ability to do otherwise as key to freedom from those that emphasize self-determination (see the entry, Free will). Grosseteste's theory as described above would seem to belong to the former class, and this conclusion is also indicated by arguments he gives for the existence of free decision, which point to a wide range of phenomena regarding which we believe that the agent could have done otherwise. Even so, there is some indication of a deeper self-determination account. For Grosseteste holds that the will's capacity for opposites itself is contained in its power to will and move itself (Lewis, 2017, 255). Thus Grosseteste sees the will as a self-mover. Unfortunately, he leaves this issue unexplored, including it at the end of his treatise among a list of topics to be considered on another occasion.


## 10. Exemplarism, Truth and Illumination


### 10.1 Exemplarism


 Grosseteste's exemplarism (see Lynch 1941) is in part an
adaptation of Plato's theory of Ideas to a Christian framework. Like
other medieval thinkers, Grosseteste takes the existence of an
eternal, self-subsistent realm of Platonic Ideas to be inconsistent
with the dependence of all things on God. Nevertheless, following
Augustine and Seneca, he does not reject the Platonic ideas
outright. Rather, he treats them as eternal models (*exempla*)
or, as he also calls them, reasons (*rationes*) of things in
God's mind. Like the Platonic ideas, these reasons function as
paradigms or models created things can accord with or fall short of.
God looks to these reasons of things in creation, somewhat as a
craftsman looks to the idea in his mind of what he is to make. 


 Given that God is absolutely simple, the reasons of things in
God's mind must in the final analysis be identified with God. Thus
Grosseteste moves between speaking of the reasons in God's mind as
exemplars or models and speaking of God himself as such. Indeed, he
describes God, following Augustine in the *Confessions* and
*De libero arbitrio*, as first form, noting expressly that he
is not using the notion of form in this connection in Aristotle's
sense as what enters into a form-matter composite (as the first form
corporeity does) (Luard 1861, 4; Goering and Mantello 2010, 38). In *On the Halt of Causes* he
identifies the first form, God, with "the form that is both a model
and that in virtue of which a thing is" and notes that this form "is
not conjoined with a thing but exists on its own, simple and
separate. This is the first form, and how it is the first form is hard
to explain" (Baur 1912, 125).


### 10.2 Truth


 Grosseteste wrote in a tradition that employed the concept of
truth in a number of different contexts. We may speak not only of the
truth of propositions or thoughts, but also of things--e.g. of
a tree or a human being--and God himself or the eternal Word is
identified with truth. In his treatise *On Truth* Grosseteste
takes up the question, raised by Anselm, whether there is just one
truth (*veritas*), God, or many truths (*veritates*).
But much of his account is concerned to present a uniform conception
of truth that embraces these different applications of the term noted
above. The doctrine of eternal exemplar forms plays an important role
in this account.


 According to Grosseteste's treatise *On Truth*, truth is
the conformity or adequation of things and speech, or more
particularly, the thought expressed by speech. This conception of
truth as adequation had only recently entered the Latin West, but
Grosseteste gives it a twist all his own, taking the speech in
question to be that of God, the eternal Word. Thus truth
(*veritas*) is a conformity between things and the eternal
Word. Grosseteste claims that the eternal Word is itself its very own
conformity to itself and thus may be identified with truth. As for
created things, their truth is their conformity to their eternal model
or reason in the eternal Word. Likewise, the truth of 
propositions--a subclass of things--is their conformity to their
eternal model or reason in the eternal Word. This, on first
appearance, would appear to clash with the idea that a proposition's
truth is not its conformity to anything in God, but rather to the
state of affairs in the world whose obtaining it asserts; but this
appearance is deceptive. A thing's conformity to its eternal reason,
its truth, is its having the being its exemplar specifies. Now,
Grosseteste holds that created items have two kinds of being or
perfection. In his commentary on the *Posterior Analytics* he
holds that the second perfection of a thing is "the completion of the
activity of the thing to which it has, as such, been established to be
fitted and for the sake of which it has been established" (Rossi 1981,
240). The first being of a thing is its simply being the kind of
thing it is. Thus, there is a twofold conformity possible of things
to their eternal reasons. On the one hand, the eternal reason of a
thing specifies the very kind of thing that thing is, and simply in
virtue of existing as an item of a determinate kind a thing will
necessarily conform to its exemplar in this respect and be true. Thus
all human beings and all propositions are true, in this sense, in that
they are the kinds of things they are, this being specified by their
exemplar. A human being is a composite of body and soul, and a
proposition is "the statement of one thing about another or one thing
from another" (Baur 1912, 143). On the other hand, the eternal reason
specifies the second perfection a thing ought to have but may
nonetheless lack. In this sense a human being will be a false human
being if, for example, she is vicious, falling short of the perfection
of virtue specified in the eternal reason of a human being. Likewise,
a proposition will be a false proposition if it fails to perform the
function of a proposition, this being to state things as they in fact
are in the world. Thus, the ordinary notion of propositional truth,
described by Aristotle as "to so be in the thing signified as speech
says," is a matter of a proposition's conformity, in respect of second
being, to its eternal reason, and this is for it to perform the
function perfective of propositions, namely, to be in conformity to
the states of affairs it asserts.


 With this account of truth Grosseteste thinks he can accommodate
within one schema the divergent conceptions of truth present in his
day. As to the initial question he drew from Anselm, whether there is
just one truth or many, diverging from Anselm, who posits a single truth, he holds that there are many truths
(*veritates*), for otherwise the term "truth" could
not admit a plural or be distributed (by which he means we
could not speak of "every truth") (for the relation between Anselm's and Grosseteste's accounts of truth, see Noone 2010). Nevertheless, he concludes that
"there is a single truth that the name 'truth' everywhere
signifies and predicates--namely, the supreme
truth--though this one truth is called many truths in the many
truths of things" (Baur 1912, 139). Thus, for Grosseteste any use of
the term "truth" involves in some way a reference to the supreme
truth, God.


### 10.3 Illumination


Under Augustine's influence Grosseteste subscribes to an
illuminationist account of human knowledge, according to which human
knowledge is understood by analogy to bodily vision: as a body can
only be seen if light is shed on it and the eyes, so something can
only be known if a spiritual light is shed on it and the mind's
eye. Grosseteste presents versions of such an account in his
treatise *On Truth* and in his commentary on the *Posterior
Analytics*.


In *On Truth* Grosseteste presents an illuminationist theory
of knowledge after outlining his theory of truth. Because created
truth is a conformity between things and their eternal reasons, we can
only know created truth if we know that a created thing conforms to
its eternal reason in God. But as we can only see a body as colored if
an external light is shed on its color, rendering it actually visible
to us, so in order for us to see a created thing as true, an external
light must be shed on its truth, rendering it actually visible to
us. This truth is the adequation of the thing and its eternal reason
in God's mind, and thus an external light, the light of the Supreme
Truth, God, must be shed on both the thing and its eternal reason if
it is to be visible to the mind. Grosseteste hastens to point out that
this doesn't require that the knower see God himself or even be aware
of God, for only the pure of heart see God as he is in himself in the
face-to-face vision of God. All the same, all who know truth must in
some way have at least an unwitting cognition of the Supreme Truth and
its light, and in it a vision of the eternal reasons, that falls short
of the direct vision of God.


Grosseteste makes no reference to Aristotle's views on knowledge
in *On Truth* but draws on Augustine and Anselm. But in the
commentary on the *Posterior Analytics*, which appears to be
the earlier of the two works, he relates an illuminationist conception
of knowledge to Aristotle's account of scientific knowledge. Scholars
disagree, however, regarding Grosseteste's intentions in this
regard. Some (Gilson 1926-7, Lynch 1941, McEvoy 1982) take his
treatment of Aristotle's account of scientific knowledge to accord no
role to Aristotle's notion of abstraction, in whose place Grosseteste
instead employs an Augustinian conception of divine
illumination. Others (Marrone 1983), treating *On Truth* as the
earlier work, take Grosseteste now to reject an account of divine
illumination in our knowledge in this life and hold his references to
illumination in the context of scientific knowledge to refer to a
light the human soul itself sheds on intelligible things in a process
of abstraction understood along Aristotle's lines. The truth, however,
as Van Dyke 2009 argues, seems to be that Grosseteste is concerned to
subsume Aristotle's account of scientific knowledge under a broader
account of cognition in which divine illumination plays a crucial role
in all cognition, while at the same time he endorses the account of
scientific knowledge and abstraction presented in the *Posterior
Analytics*. The following remarks briefly examine some aspects of
this attempt. (For further discussion and more technical aspects of
Grosseteste's account of demonstrative science, see the entry on
Medieval Theories of Demonstration, as well as Crombie 1953, Evans 1983, Laird
1987, Longeway 2007, McEvoy 1982, Marrone 1983, 1986, Rossi 1995, Serene 1979, Van
Dyke 2009 and 2010, and Wallace 1972.)


The *Posterior Analytics* is concerned to provide an account
of *scientia* or "scientific knowledge." By this is
meant not scientific knowledge in the modern sense of a body of theory
based on the experimental testing of hypotheses, but rather an
understanding of the reason why a given fact obtains
(knowledge *propter quid*), as opposed to knowledge simply that
the fact does obtain (knowledge *quia*), what might be
described as a certain kind of explanatory knowledge. An Aristotelian
science is a systematization of such knowledge based on the structure
of Euclid's axiomatic geometry and employing Aristotle's syllogistic
logic. One arrives at *scientia* of a given fact by deriving it
as the conclusion of a syllogism whose premises meets certain
stringent conditions that render them explanatory of that fact. As
Grosseteste puts it, the premises or principles-i.e., starting
points-of such a syllogism must be true, immediate, prior and
better known than the conclusion, must state causes, be necessary,
concern essential connections, be universal, everlasting, and
incorruptible. A syllogism that meets these conditions is called a
demonstrative syllogism or demonstration and will provide explanatory
knowledge of its conclusion. At one point Grosseteste states that only
mathematics is comprised of demonstrations in this strict sense,
though in another passage he suggests that theology would most fully
meet these conditions, apparently meaning that the demonstrative
knowledge possible for us in this life (mathematics) is to be
distinguished from that which is possible in the afterlife
(theology). The sciences of natural phenomena do not, Grosseteste
claims, fully meet the requirements for a fully demonstrative science,
though if we relax the conditions governing demonstrations somewhat we
may speak of a demonstrative science of natural phenomena (see the
entry on Medieval Theories of Demonstration for details).


According to Grosseteste, the *Posterior Analytics* is not
concerned to provide a method for arriving at demonstrations but
rather to provide criteria to evaluate whether a given syllogism
counts as a demonstration. Nevertheless, Aristotle does discuss the
source of the principles and definitions employed in demonstrations,
and it is in considering these remarks, in particular, that
Grosseteste introduces the ideas of mental vision and the illumination
of the mind.


According to Aristotle, it is from sense experience that we obtain
the universal concepts and principles of a science. Thus, if someone
lacks a sense, he will also lack the scientific knowledge involving
the concepts and principles derived from exercise of that sense. But
Grosseteste holds that God and the intelligences (i.e., angels) know
without reliance on the senses, and the intellective power, the
highest part of the human soul, relies on no bodily sense or organ in
its proper operation. Instead, its proper operation involves a mental
vision in which one arrives at knowledge of things by viewing their
exemplar forms or reasons in an irradiation received from God or an
intelligence.


Grosseteste reconciles this doctrine with Aristotle's teachings by
holding that with rare exceptions most individuals in the present life
do not have knowledge of this sort; their intellective power is
"sick" and unable to perform its proper operation. In the
present life the highest form of knowledge possible for most human
beings is Aristotelian demonstrative science, and for this sense
experience is indeed required.


This might suggest that Grosseteste reserves the notion of mental
illumination simply for the proper operation of the intellective part
of the soul. But this is not so. Mental vision and an illumination of
the mind are involved even in the operation of our rational power in
demonstrative science.


Alluding to *Wisdom* 9: 15, Grosseteste holds the
intellective power is sick because it is darkened and weighed down by
the corrupt body. He intimates that human beings are born in this
condition, presumably as a consequence of the fall. He likens this
darkening of the mind to a cloudy day: as bodily vision is darkened by
clouds, so the operation of the cognitive powers is darkened by bodily
appearances (*phantasmata*), which obstruct our mental vision
and render it unable to see intelligible items in their purity. This
darkening of the mind, Grosseteste holds, is the source of all
error. In grasping the principles of demonstration, reason is
stimulated to leave this darkness. In a newborn human being the powers
of the rational soul are as if asleep and unable to act. But sense
experience in some way involves reason, and through repeated sense
experience reason is woken up and carried by the senses to perceptible
things. Reason then begins to distinguish and view apart the features
confused in sense experience, thereby formulating universal
concepts. Repeated experience of correlated perceptible phenomena
leads the senses to estimate an imperceptible relationship between
them--a causal connection, for example. This too awakens reason
and leads it to wonder whether this connection in fact
obtains. Grosseteste uses an example, drawn from Avicenna, of the
claim that scammony of itself causes the discharge of red
bile. Wondering whether this is true, we set up what we should now
call a controlled experiment in which we exclude other known causes of
the discharge of red bile and give someone scammony to see what will
happen. And in this way, Grosseteste writes, we arrive "from
sense at an observational (*experimentale*) universal
principle" (Rossi 1981, 215).


Grosseteste describes this as the process in which the mind is
stimulated on the occasion of sense experience to seek and find its
own light--to turn from corruptible corporeal objects to
intelligible things. The mind moves out of the darkness it is in to
find a trace of its light, which stands to it as the sun stands to the
eyes in bodily vision. As he puts it in discussing certainty,
"there is a spiritual light shed on intelligible things and the
mind's eye, and this light is related to the inner eye and
intelligible things in the way the bodily sun is related to bodily
eyes and visible bodily things" (Rossi 1981,
240-241). Understanding (*intellectus*) and demonstrative
knowledge are "like the vision of healthy eyes through the
medium of pure air with clear light spread over the colored
object...Understanding and demonstrative knowledge apprehend
things in the purity of their essence, as they are in
themselves" (Rossi 1981, 279-280).


These remarks indicate that for Grosseteste some sort of spiritual
light and vision is involved in scientific knowledge, but they also
strongly suggest that Grosseteste is wedded to an Aristotelian account
in which the human mind abstracts intelligible items from the data of
sense. These intelligible items would appear to be the genera and
species of created things, viewed as immanent Aristotelian universals,
the second lowest level of a hierarchy of universals Grosseteste sets
out in the commentary, the highest being the reasons of things in the
divine mind. But what exactly is the nature of the vision and
illumination involved in scientific knowledge? In particular, in his
account of demonstrative science, and thus of the sort of knowledge
possible for most of us in this life, is Grosseteste employing a
notion of *divine* illumination, as he clearly does in his
treatise *On Truth*?


Marrone 1983, ch. 6, suggests he is not: the light Grosseteste
mentions is a light, he thinks, that the mind itself sheds on items to
render them intelligible and the notions of light and vision play no
essential role in Grosseteste's understanding of Aristotelian science:
the commentary displays a movement away from the conception of
knowledge in *On Truth* in terms of divine illumination towards
a purely naturalistic conception of knowledge. But this view
presupposes the implausible chronology according to which *On
Truth* was written before the commentary and, as van Dyke 2009
points out, fits poorly with Grosseteste's analogy between the light
involved in scientific knowledge and the light shed by the sun in
bodily vision, which comes from a source *apart* from the
senses. So too, it seems, the light involved in scientific knowledge
is a light that a source apart from the mind, namely God (or possibly
an intelligence), sheds on objects of scientific knowledge so as to
render them actually intelligible, in the way the light the sun sheds
on bodies makes them actually visible. 


## 11. Scientific Method


Grosseteste's numerous short scientific works made no significant
contribution to scientific theory. Yet it has been argued that
Grosseteste played a key role in the development of scientific
*method*. In particular, Crombie 1955 (a summary of Crombie
1953) has claimed (1) that Grosseteste was the first in the Latin West
to develop an account of an experimental method in science (98); (2)
that he "seems to have been the first writer to make systematic
use of a method of experimental verification and falsification"
(107); (3) that he gave a "special importance to mathematics in
attempting to provide scientific explanations of the physical
world" (111). These claims have been the subject of
considerable debate. 


 The claim that Grosseteste developed an account of experimental
method in science puts great weight on the aforementioned passage in
which Grosseteste describes a controlled experiment to see whether
scammony causes the discharge of red bile. There can be little doubt
that Grosseteste does indeed have in mind the idea of a controlled
experiment. The question, however, is whether Grosseteste makes the
notion of controlled experiment part of a general account of a
scientific method for arriving at the principles of demonstrative
science. The evidence that he does so is not strong. The discussion of
scammony is the only reference to controlled experiment in his
writings, and when Grosseteste refers back to this discussion later in
the commentary as explaining how we come to acquire experiential
principles, the notion of controlled experiment is sometimes
inapplicable--as for example, regarding our knowledge of
the cause of an eclipse. Moreover, Grosseteste is quite prepared to
grant that in some cases we can know causal connections after only a
single perception (see Marrone 1986). On balance, we may say that
Grosseteste did employ the notion of controlled
experiment and related it to demonstrative science, but he hardly set
it up as the method by which such knowledge is to be obtained; it is
one among many ways of arriving at such knowledge and is not accorded
the emphasis it has been given in scholarly commentary.


 As for Grosseteste's actual practice in his scientific writings,
if by an experimental method is meant a method of controlled
experiment, then it must be said that Grosseteste makes no use of such
a method in these writings. He arrives at his conclusions in his
scientific writings on the basis of a mix of considerations. He
appeals to authority and everyday observation (*"experimentum"*
in Latin) and makes use of thought experiments and certain
metaphysical assumptions, such as that "every operation of
nature occurs in the most finite, ordered, shortest and best way
possible for it" (Baur 1912, 75). Nowhere does he describe a
controlled experiment as the basis of his conclusions (see Eastwood
1968, regarding Grosseteste's works in optics). We may grant that
Grossetete does cite empirical observation as one factor among others
when he assesses the adequacy of certain accounts of natural
phenomena, but this is far from employing a method of experimental
verification and falsification in the sense of a controlled
experiment.


 The claim that Grosseteste gave a "special importance to
mathematics in attempting to provide scientific explanations of the
physical world" is on a stronger footing. In the opening of the
treatise *On Lines, Angles and Figures* Grosseteste remarks
that "the consideration of lines, angles and figures is of the
greatest utility since it is impossible for natural philosophy to be
known without them .... All causes of natural effects have to be
given through lines, angles and figures, for otherwise it is
impossible for the reason why (*propter quid*) to be known in
them" (Baur 1912, 59-60). In the treatise, *On the Nature of
Places*, which is a continuation of *On Lines, Angles and
Figures*, Grosseteste sums up the preceding text with the remark
that "the diligent investigator of natural phenomena can give
the causes of all natural effects, therefore, in this way by the rules
and roots and foundations given from the power of geometry"
(Baur 1912, 65). Undoubtedly, then, Grosseteste saw a key role for
geometry in the explanation of natural phenomena. 


 At the basis of this view was Grosseteste's view that natural
agents act by the multiplication of their power or species, a view
Roger Bacon was to develop in detail. Grosseteste was, of course,
thinking of the action of light. He holds that knowledge *propter
quid* must be through angles, lines and figures because a
"natural agent multiplies its power from itself to what it acts
upon, whether it act upon the senses or upon matter" (Baur 1912,
60). Grosseteste holds that the intensity of operation of the natural
agent will be a matter of its distance from what it acts upon, the
angle at which it strikes it, and the figure in which it multiplies
its operation, this being either a sphere or cone. He establishes
certain rudimentary rules to this effect, such as that the shorter the
distance, the stronger the operation. 


The remarks above should not blind us to the fact that Grosseteste
was deeply concerned with the detailed investigation of natural
phenomena. It was the inspiration of this attitude of mind, together
with Grosseteste's emphasis on the importance of mathematics, that was
perhaps his chief legacy to thinkers in fourteenth-century Oxford who
were developing the beginnings of a mathematical physics.


## 12. Influence


By the fourteenth century, Grosseteste had achieved the unusual
status of being an authoritative figure for Oxford
thinkers--someone from whose writings quotations might be
marshalled, on the strength of his name, in defense of one's
views. Thus, both Thomas Bradwardine and Thomas Buckingham appeal to
Grosseteste in support of their conflicting views on future
contingency. John Wyclif likewise appeals to Grosseteste as a fellow
traveller in support of his views on the continuum, among other
issues, ranking him with Plato, Democritus and Augustine as one of the
greatest of thinkers. Such appeals are signs of the reverence with
which Grosseteste was held in fourteenth-century Oxford. 


The influence of specific ideas of Grosseteste's may be found in
numerous thinkers, especially those who flourished at Oxford. Their
number includes Adam of Wodeham, John Wyclif, Robert Kilwardby, Thomas Bradwardine, Thomas Buckingham, Thomas of York, Walter Burley, William of Alnwick, William of Ockham, and others. But his greatest influence as
a philosopher, if we leave aside his commentary on the *Posterior analytics*, was perhaps as a source of ideas for thinkers
flourishing in the first half of the thirteenth century. In
particular, Richard Rufus of Cornwall makes extensive use of
Grosseteste's writings in his large *Scriptum* on Aristotle's
*Metaphysics* and his Oxford commentary on the *Sentences*
of Peter Lombard, as does his Oxford contemporary Richard Fishacre in
his commentary on the *Sentences*. These thinkers were heavily
influenced by Grosseteste's *On Free Decision* as well as by his
writings on the eternity of the world. Rufus also praises
Grosseteste's scientific and mathematical expertise, as does Roger
Bacon, a man by temperament more given to scorn than praise.


Grosseteste's philosophical influence on the Continent appears to
have been largely as a scholar of Aristotle. His commentary on the
*Posterior Analytics* achieved renown across the Continent and
was used throughout the middle ages (for its influence in Britain see Rossi 2012), and the same was true of his
translation of the *Ethics*. Indeed, these two pieces of
Aristotelian scholarship alone would have sufficed to acquire for
Grossetete an important place in the history of medieval thought. One exception, however, is the fourteenth-century French thinker, Nicole Oresme, who makes use of a number of Grosseteste's philosophical and scientific writings in his works, most notably in his *Questiones super Physicam*.