## 1. Life




Born in Rome most probably in the fifth decade of the thirteenth
century, Giles was the first outstanding theologian of the relatively
recently founded Order of the Augustinian Hermits. Nothing more is
known about his origins: the statement that he belonged to the famous
Roman family of the Colonna seems to go back to Jordan of Saxony's
*Liber Vitasfratrum* (second half of the 14th century), but is
completely missing from contemporary, 13th-century sources. From Giles'
will we know that he was sent to Paris to study in the convent of his
Order. At the beginning he must have followed the courses either of a
secular master or of a theologian belonging to a different Order, as
the Augustinian friars did not have a regent master at the time.
Probably he was a pupil of Aquinas' in the years 1269-1272. He
commented on the Sentences at the beginning of the 1270s. In following
years he most probably wrote also a large number of his commentaries on
Aristotle.




The year 1277 marked a turning-point in his career: Giles was
involved in the condemnation of the heterodox Aristotelianism issued by
the Parisian bishop Etienne Tempier, although the process against him
must be distinguished from the famous decree of the 7 of March 1277, as
Robert Wielockx has shown. After 1277 Giles must have abandoned Paris,
but his presence is attested in Italy not earlier than 1281. Before
leaving Paris he completed his De regimine principum, which is
dedicated to the young Philip, the future Philip the Fair.




Between 1281 and 1284 Giles played an important role in the
government of his Order, taking part in various chapters held in Italy.
At the provincial chapter of Tuscania (nowadays in Lazio, Italy) in
1285 he acted as vicar of the prior general of his Order, Clement of
Osimo.




In 1285, Giles' doctrine was examined again; after recanting only a
part of what had been previously condemned in 1277, he was allowed to
teach again; by 1287 he is referred to as a master of theology. His
university quodlibeta go back to this period, from the academic year
1285/86 to 1292/93 (Pini 2006, Wielockx 2014). This success enhanced
Giles of Rome's authority even more in his Order, whose general
chapter of Florence decreed that Giles' works (even future ones)
should be considered as the official doctrine of the Order, to be
defended by all Augustinian bachelors and masters. In 1292, at the
General Chapter of Rome he was elected prior general of his Order.




Benedict Caetani's election to the papal see marked a further
radical change in his career, as Boniface VIII appointed him archbishop
of Bourges in 1295. As a matter of fact, Giles was very often absent
from his see, spending extended periods of time at the papal curia. In
his *De renuntiatione*, he defended the legitimacy of
Celestine's abdication, and, consequently, of Boniface' s
election. When the contrast between Boniface VIII and Philip IV reached
its most critical point, he continued to side staunchly with the pope.
An important sermon defending the papal position has been
discovered by Concetta Luna, and Giles' *De ecclesiastica
potestate* undoubtedly ranks among the sources of *Unam
Sanctam*.




Giles' prestige decreased after Boniface' death, and even more
with the rise of Clement V to the papal throne. Before being elected
pope, Betrand de Got, as archbishop of Bourdeaux, had had serious
conflicts with Giles. This unfavorable change, however, did not prevent
Giles from playing a significant role in the debates of his time.
Around 1305-6 he took part in a commission which examined and condemned
the eucharistic doctrine of John of Paris, a former adversary of Giles'
during the conflict between Philip the Fair and Boniface. In the
discussions concerning the Templars which eventually led to the
suppression of the Order, Giles sided with Philip the Fair, attacking
the Templars and devoting a whole tract, *Contra exemptos*, to
the thesis that their exemption from episcopal jurisdiction was the
cause of their abuses (Jordan 2005). During the Council of Vienne Giles was asked to
draw a list of errors extracted from the works of Peter John Olivi:
three of them were officially condemned by the Council. On December 22,
1316 he died at the papal Curia at Avignon (For further details see Del
Punta-Donati-Luna 1993, Briggs 2016).



Relying on manuscript evidence and other sources, Giorgio Pini (2005)
could identify which kind of theological and philosophical works Giles
read, studied and had copied for himself during his long intellectual
career. Pini distinguishes three main periods. In the first one,
before 1277, quite unsurprisingly, he reads Aquinas (not only the
Commentary on the Sentences of the Dominican master, but also his
later works), Aristotle (e. g. in these years Giles owns and annotates
a copy of the *Nicomachean Ethics*), Avicenna and Averroes. He
is also very well acquainted with the works of Ps. Denis the
Aeropagite. In the second period (1277-1285), when forced to leave the
academic milieu, Giles widens his interests. He studies many works of
Anselm's (while most theologians of his time were very selective in
their knowledge of this author), and makes acquaintance with works by
Augustine, such as Confessions and *Soliloquia*, that were
quite unusual readings for an academic theologian. In the this period
(from his return to the Parisian Faculty of Theology [1285] to his
death) Giles studies almost entirely the available works by Augustine
and acquires also rare treatises by Proclus. Giles' increasing
attention for Augustine is mirrored in his mature works and will
influence also the theological orientation of his own Order in the
following decades (Pini 2012).


## 2. Logic and Rhetoric




After Rene Antoine Gauthier identified in the master Guillaume
Arnauld the real author of the *Lectura supra logicam veterem*
attributed to Giles of Rome (Tabarroni 1988), interest in logical
works focused mainly on his Commentaries on the *Sophistici
Elenchi* and on *Posterior Analytics*. In his treatment of
the *fallacia figurae dictionis* Giles proves to be a brilliant
and original representative of "modistic logic", who bases
his solutions mainly on the semantics of *intentiones*
(Tabarroni 1991). This does not imply, however, that he always agrees
with the Modists. One of the most relevant disagreements regards
signification. He doesn't think that signification is the essential
form of the linguistic sign. On the contrary, sharing a a much more
widespread view in his times, to him, the signification of
*e.g.* a name is a concept (or more precisely a definition),
which in turn signifies the thing. This signification is not natural,
but conventional. The linguistic sign signifies in a natural way only
its mental image, which is essential to human acts of speech (Marmo
2016). Alessandro Conti (1992) investigated Giles' Commentary on
*Posterior Analytics* as an example of his theory of truth,
which brings to completion Aquinas' shift from Augustine's influence
to the Aristotelian approach. Bertagna (2002-2004) investigated
the structure of this commentary, while Longeway (2002) and Corbini
(2002) drew scholars' attention to Giles' epistemic logic. Giles of
Rome also authored the most important Commentary on the Rhetoric of
the Latin medieval tradition, which earned him the honorific title of
*expositor* of this book and influenced all later medieval
commentaries. Costantino Marmo studied Giles' approach to the
different translations to which he had access and showed how he
developed Aquinas' theory of passions in commenting on the relevant
portions of Aristotle's text (Marmo 1991), trying to solve some
problems left open by Aquinas. It has been suggested that Giles
considers rhetoric to be a sort of "logic" of ethics and
politics: this brilliant interpretation needs, however, further
development and articulation (Staico 1992). Janet Coleman (2000) also
maintained that Aristotle's rhetorical method determines the substance
of Giles' *De regimine principum*, but one should also take
into account also Lidia Lanza's (2001) remarks. Marmo (2016) pointed
out that if rhetoric is the *modus sciendi* more apt to moral
sciences, this does not imply that it contributes to moral or
political knowledge, since this is derived from the principles proper
of ethics or politics.


## 3. Metaphysics and Theory of Knowledge




Traditionally, Giles was described as a "faithful"
disciple of Aquinas'. Nowadays such a judgment is not accepted
by scholars. After Concetta Luna argued persuasively in favor of the
authenticity of the *Reportatio*, it became clear that Giles,
already in the first stages of his career, develops his positions
taking Aquinas' teaching as a starting point for his own
reflection, but criticizes and corrects the doctrines of the Dominican
master in many aspects. Luna could also establish that Giles reworked
his *Lectura* on the Sentences (handed down to us as a
*reportatio*) into an *ordinatio* only for the first two
books. However, while the first book was completed shortly after the
*Lectura*, that is, during the years 1271-1273, the
second book had to wait for completion until 1309. Luna gathered
impressive evidence suggesting that the *Ordinatio* of the
third book that goes under the name of Giles is, in fact,
spurious. Broadly speaking, Giles' "philosophical
project" tends to discuss critically Aquinas' position in
order to improve the solutions he offered, without, however, trying to
discard them radically. Recently, Katherine Konig-Pralong showed
that this is the case for the debate about the natural desire for
knowledge: although defended in in the context of a discussion with
Henry of Ghent, Giles' position does not coincide with that of
Aquinas. According to him, in fact, human beings possess a natural
desire for knowledge that is satisfied by a limited understanding of
separate substances (Konig-Pralong 2014). The same holds true
also for one of the most famous topics of his discussion with Henry of
Ghent, the distinction between "essence" and
"existence". In this case, Giles radicalizes
Aquinas' doctrine of the real distinction, asserting that
existence must be conceived as a "*res addita*"
[thing added] to essence (Pickave 2016). Although the final
result of his theory was considered closer to Avicenna's
solution than to that of Aquinas, Giles nevertheless develops it
starting from Aquinas' own position (Wippel 1981), as emerges
already from his Questions on the Metaphysics (Conti 2014). The
connection of this issue with the discussion with Henry of Ghent about
the concept of "creation" was investigated in depth by
Giorgio Pini (1992), who could show how Giles, while defending Aquinas
and thereby the possibility of using some Aristotelian principles in
an orthodox account of creation, goes beyond the positions of the
Dominican master, e. g. asserting the identity of
"*esse*" and "*creatio*"(see
also Porro 2014, Cross 2016). Giles advocated the compatibility of
Aristotelian doctrine with Christian faith also in his commentary on
the short treatise *De bona fortuna* attributed to Aristotle,
but in reality consisting in a compilation of passages taken from the
*Ethica eudemia* and the *Magna moralia*. The
interpretation of the concept of "bona fortuna" in those
texts implied problemas connected with contingency, necessity and the
interplay between divine causality and natural events. As
Valerie Cordonnier (2104) showed, Giles' solution was
attacked by Henry of Ghent as leading to necessitarism.




As to the debate about the unicity of substantial form, Giles'
position evolves during time. If we leave aside the *Errores
philosophorum*, since the authenticity of this work has been
contested with serious arguments (Bruni 1935, Koch 1944, Donati 1990b,
Luna 1990), we can notice that Giles changes his position from the
*Contra gradus et pluralitatem formarum* (between the end of
1277 and the beginning of 1278), where he, against Henry of Ghent
denies plurality of forms for every compound (Wilson 2014), to later
works, where he takes a more cautious stance in particular concerning
man. The principle of individuation is identified, as in Aquinas, with
"materia signata quantitate", that is, matter designated
by its dimensions. According to Giles, who criticizes also Richard of
Mediavilla on this point, matter is pure potentiality and therefore
cannot be distinguished into different kinds. For this reason, he
cannot accept Aquinas' doctrine that the incorruptibility of celestial
bodies derives from the peculiar nature of their matter (Donati
1986). In Giles' opinion celestial bodies are not incorruptible
because their matter is different from the matter of sublunar bodies,
but rather because their *quantitas materiae* cannot change its
determinate dimensions. This is but one application of Giles' famous
doctrine of "indeterminate dimensions". Modifying
Averroes' doctrine in this respect, Giles argues that a portion of
matter, in order to be able to receive a form, needs to possess
already a sort of quantity. Such quantity, however, should not be
identified with the determinate dimensions a body possesses, but is
rather a *quantitas* which remains the same during processes
such as rarefaction and condensation. Giles' notion of
*quantitas materiae*, which is not only generically extension
or three-dimensionality, but seems to represent an unchangeable given
"amount" of matter pertaining to a body, has been
considered comparable, some differences notwithstanding, to the modern
notion of mass (Donati 1988, Donati-Trifogli 2016).




After the condemnation of 1277, a significant change can be noticed in
Giles' position also in his solution of the problem of the eternity of
the world. At the beginning of his career he admitted the theoretical
possibility of the eternity of the world, although rejecting
Aristotle's arguments proving the actual eternity of the world. Later
he shifted to a more " Augustinian" stance, rejecting the
hypothesis of a creation "*ab aeterno*" and
admitting that it is possible to prove the temporality of creation,
although he finds that no conclusive argument has been advanced so far
(but see also Cross 2016). Giles was much more steadfast in his
opposition to another major tenet of "Averroistic"
doctrine, that is the unicity of the possible intellect. He maintained
that the possibility of actual knowledge on the part of the individual
depends necessarily on the fact that each body is informed by its own
intellective soul, which is its form. For the same reasons Giles also
rejected the unicity of the agent intellect, a doctrine he attributed
to Avicenna (Del Punta-Donati-Luna 1993, Conolly 2007).



Giles' account of knowledge is indebted to Aquinas, but, again,
reveals many original features. In the first place, he insists on a
strictly causal interpretation -- be it direct or via a medium
-- of the cognitive process, both at the level of sensory and
intellectual acts. Secondly, the Augustinian master doesn't conceive
of the role of "intelligible species" or *formales
expressiones* as he often writes, as essential to the process of
cognition in itself. As Giorgio Pini (2016) has shown, the
intelligible species is necessary only when the object cannot be
present in the intellect directly. Admittedly, this direct presence is
possible only in the beatific vision (after death) and most probably
in the cognition angels have of themselves. For human knowledge in
this life, on the contrary, intelligible species fulfill a necessary
function, as causal proxies, as Pini (2016) writes, mediating between
the object and the cognitive power. Difficulties for Giles' account
emerge especially when it comes to defining the ontological status of
the species. The interpretation of cognition in terms of causation
seems in fact to imply, according to Giles' own presuppositions, that
the species belongs to the same kind of the thing it represents. On
the other hand, the intelligible species is in the intellect, and this
presence is explained in terms of inherence of an accident (the
species) in a substance. Giles himself is aware of this difficulty,
since in one passage he claims that such species are in themselves
neither substances nor accidents. They can, however, be
"reduced" to the kind to which the represented thing
belongs. Pini (2016) is right in pointing out that Giles' answer seems
to raise more problems than it can solve.


## 4. Natural Philosophy


 Studies concerning Giles' natural philosophy focused mainly on his
treatment of some pivotal concepts of Aristotle's Physics. Cecilia
Trifogli opened new perspectives in this field, devoting her attention
to the notions of place and motion (especially in the void, see
Trifogli 1992), underlining that "Giles' emphasis on the
role of place in the description of motion seems to lead to a
quantitative and relational notion of place. Giles, however, does not
completely substitute the Aristotelian notion of place for that of
place as distance. Place as distance is only one of the two notions of
place which appear in his commentary. The other, which is related to
material place, assumes an intrinsic connection between place and the
located body that cannot be founded on distance alone" (Trifogli
1990a, 350). Giles' distinction was referred to as an opposition
between material place (the limit of the containing body) and formal
place (distance from the fixed points of the universe)
(Donati-Trifogli 2016). Trifogli also investigated Giles' notions of
time and infinity, emphasizing that his whole approach to natural
philosophy is distinguished by a tendency towards a metaphysical
interpretation of Aristotelian concepts, as opposed to a physical and
quantitative one (Trifogli 1990b, 1991). For example, Giles conceives
of time not as a quantity pertaining to every kind of motion, but
rather as the same thing as motion, seen under a different aspect. His
concept of time rests in fact essentially on a broad notion of
succession, which allows him on one hand to retain the unity of the
concept of time, but, on the other hand, to acknowledge the existence
of different times (Trifogli 1990b, Donati-Trifogli 2016) Giles
distinguishes between two kinds of duration: extrinsic duration is the
time of celestial motion, and is obviously one in number. Intrinsic
duration depends on the different motions taking place in the
sublunary world and is therefore plural (Donati-Trifogli 2016). A
similar attitude emerges also from the analysis of Giles' controversy
on angelic time with Henry of Ghent (Porro 1988, Porro 1991, but see
also Faes de Mottoni 1983). Both authors thought that the time in
which angels exist, unlike sublunar time, is a discrete succession of
instants. Giles and Henry disagreed, however, on the relationship
existing between angelic and sublunar time. In particular, Henry
rejected Giles' thesis that more instants of angelic time can
correspond to one and the same instant of sublunar time. This
difference of opinion rested in part on diverging concepts of angelic
motion, which can be istantaneous according to Henry, but not
according to Giles.


## 5. Between Philosophy and Medicine




In 2008, Romana Martorelli Vico published the first critical edition
of Giles' *De formatione corporis humani in utero*. With this
work, completed between 1285 and 1295, Giles took a stance in the much
debated question of the respective roles of male and female parents in
conception. The Galenist view, going back to Hippocrates, was that
both male and female contributed sperm, so that the offspring could
have characteristics from both parents. On the contrary, Aristotle had
held that only the male alone contributed sperm containing an active
and formal principle to conception, while the female provided only the
matter of the fetus. Giles was well acquainted with these different
positions and with the efforts to reconcile the diverging approaches
of *medici* and *philosophi*, which could be traced back to
Avicenna. Leaning on Averroes' *Colliget*, however, Giles
rejected any attempt to attribute a formal role to the female sperm,
even if it is conceived as subordinate to the male one. On the contrary
he maintained that it can contribute only in a passive way to
conception, while what was called "female sperm", i.e., the
vaginal secretion, has a subservient, helpful but by no means necessary
function. It helps the male sperm to inseminate female matter, but does
not add anything essential to the new being. In this way, Giles
intended to stress the superiority of the philosophical, theoretical
approach to such problems with respect to the traditions of medical
learning, even when the latter seemed to be supported by empirical evidence
(Hewson 1975; Martorelli Vico 1988). Empirical evidence such as the
resemblance of the offspring to the mother was e.g., explained away as
an example of stronger resistance of female matter to the action of
form (Martorelli Vico 2002). After conception the human embryo begins a
development which goes through different stages. Comparing these stages
to the embryos of various animals Giles, like Thomas Aquinas, supported
an interpretation of the fetal development which would be exploited
many centuries later by the so-called "recapitulation
theory" (Hewson 1975, 99). Giles maintained, however, that
"the organic fetal body is not to be called a pig, a bear, or a
monkey, but something immediately disposed to becoming man"
(Hewson 1975, 100). This position apparently implies that human life
does not fully begin at the moment of conception. Although such a
thesis can be brought to bear on the moral judgment concerning
abortion, Giles does not seem interested in tackling from this point of
view an issue which would become central for what nowadays is called
bioethics.


## 6. Ethics and Political Theory




In the debate on the respective roles of intellect and will in the
determination of human action Giles' position underwent an evolution,
while he seems to be in search of an intermediate position, a sort of
compromise between the theory of Henry of Ghent and that of Geoffrey
of Fontaines. Giles maintains, in fact, that will is a passive potency
and can not "move" itself, but always needs an object, a
"bonum apprehensum". This starting point however, does not
rule out its freedom, because will, even if is moved
"moved" by its object, can determine itself and other
potencies with regard to action. This view of Giles' is consistent
with his mature interpretation of the relationship existing between
knowledge and will in the sinner. Committing a sin implies an
ignorance of the real good, but this ignorance is not the primary
cause of the wrong behavior, because it is an effect of the will,
which, affected by *malicia*, corrupts the judgment of the
reason (Macken 1977, Eardley 2003, Pini 2006, Eardley 2016, but see
also Cross 2016).




Giles of Rome exerted considerable influence also in other fields of
ethics, such as the theory of virtues. The most developed expression of
his position is not to be found in a Commentary on Aristotle, but
rather in his *De regimine principum*, the most successful
"mirror of princes" of medieval political thought, which is
still conserved in more than 300 manuscripts in its original Latin
version, to which many translations in European vernaculars must be
added. Written most probably between 1277 and 1280 the *De
regimine* is acknowledged to be one of the most successful attempts
at mediating Aristotle's practical philosophy, and in particular his
"ethical and political language" to the Latin West. Giles
was the first to structure a mirror of princes in three books along the
lines of a scheme -- *ethica-oeconomica-politica* -- which
played an important role in the reception of Aristotle's moral and
political philosophy in the Middle Ages (Lambertini 1988). The author
takes great care to give the impression that he is mainly relying on
Aristotle's text, providing numerous quotations from the
*Nichomachean Ethics*, from the *Politics* and from the
*Rethoric.* Scholars should not overlook, however, that his
reception of Aristotle is not as direct as it can seem and that Giles
is deeply influenced by a tradition in the interpretation of
Aristotle's practical philosophy. In this tradition Aquinas plays a
very important role for Giles, so that, while Aristotle is the
authority who is quoted on almost every occasion, it is the unnamed
Aquinas who, with his *Sententia libri Politicorum*, *De
regno*, *Summa Theologiae*, exerts a really decisive
influence on *De regimine*. While discussing particular topics,
Giles skillfully adapts Aristotle to his own purposes. This emerges
with clarity in the first book, devoted to ethics, where Giles'
classification of virtues is heavily dependent on the *Summa
Theologiae* and, therefore, on Aquinas' reinterpretation of the
Aristotelian heritage. For example, Giles here defines
*prudentia* as a *virtus media*, sharing the nature of
moral as well as of intellectual ones, a doctrine which can by no
means be traced back to the Stagirite (Lambertini 1991, 1992, 1995,
2000). In the second book Giles deals with the ethics of man as head
of the family, covering many topics, from children rearing and
education to the rule over servants. To this purpose, he exploits a
wide range of sources, and also medicine authors (Lambertini 1988,
Martorelli Vico 2008). As Giles wrote his De regimine, the
pseudo-Aristotelian *Oeconomica* were not yet available in
traslation to the Latin West; still, he managed to discuss also
economic topics, as far as they are relevant for the household of a
royal family or for a high-class household in general. Here he condemns
usury, criticizes other economic practices as not suitable for a
prince, and insists on the primary role agricolture should play
(Lambertini 2015) 




The most famous example of this selective attitude towards
Aristotle's works, however, belongs rather to the field of political
theory. In the third book of *De regimine* Giles wants to prove
that monarchy is the absolutely best form of government. The first
arguments he puts forward in favor of monarchy are not taken from
Aristotle's *Politics*, but from Aquinas' *De regno*.
Then some arguments against monarchy which could be read in the
*Politics* are presented as objections that Aristotle puts forth
for subsequent refutation. At the end, Giles states squarely that
Aristotle supports monarchy as the absolutely best form of monarchy and
corroborates his assertion with an argument, which, in the
*Politics*, actually goes in the opposite direction (Lambertini
1990). One could provide several other examples to show that
the *De regimine* succeeded in presenting itself as a
simplified exposition and explanation of Aristotle's thought in
practical philosophy, but at the same time transmitted to Giles'
readers a strongly biased interpretation of the Stagirite. The fact
that the *De regimine* was often used as a tool to have easier
access to Aristotle's political theory deeply influenced, therefore,
the way the Latin West read and understood
Aristotle's *Politics* in the Late Middle Ages (e.g. Lambertini
2017). Recent codicological studies on the diffusion of *De
regimine'* manuscripts do in fact show that many possessors
of the manuscripts most probably used them for study (See *Opera
Omnia* I.1/11, *Catalogo dei manoscritti, De regimine*;
Briggs 1999). Giles' *De regimine* was also translated into
different vernaculars (Perret 2011, Papi 2016). Graham McAleer (1999)
pointed to the fact that Giles' Commentary on the Sentences has been
almost neglected as a source for Giles' political philosophy. Studying
distinction 22 and 44 of the II book, he found that in these texts
Giles' account of the origin of political authority among human beings
after the Fall diverges from what one can read in *De regimine
principum* and reveals a profound influence by Augustine, while
Aristotle does not play the important role he had in Giles' mirror for
princes. One should also take into consideration that
Giles' *Ordinatio* of the second book was completed in 1309,
that is at least 25 years after *De regimine* and could witness
to an evolution in Giles' thought. As a matter of fact, the much
earlier *reportatio* does not tackle such issues at all
(Lambertini 2014).




While in the *De regimine* Giles carefully avoids any
reference to the thorny problem of the relationship between secular and
ecclesiastical power, his later writings which are relevant for
political theory deal first and foremost with ecclesiological problems.
This holds true for his treatise *De renuntiatione papae*
(1297-1298) where Giles defends the lawfulness of Celestine's
abdication against the arguments put forward by the Colonna cardinals
in their first appeal against Boniface VIII. From the point of view of
the history of political thought it is relevant that Giles argues that
papal power, although of divine origin, is conferred on a particular
individual by a human act, namely, by the election of the cardinals.
Here Giles is countering the Colonna arguments that papal dignity
cannot cease to reside in a pope until he dies, because the pontificate
depends on God's will, and stresses the fact that divine intention in
this case becomes effective through the mediation of human agents, that
is, through the consent of the electors and of the elected. A
jurisdiction which is given by the consent of men, however, can also be
removed by their consent through a reverse procedure. This does not
amount to saying that the pope can be deposed (except in case of
heresy), because, according to Giles, the pope is above the law and has
no earthly authority above him. He can however, depose himself, that
is, abdicate. Just as for his election the consent of his electors and
of the elected was necessary, so also for the removal of the pope from
office his consent is decisive (Eastman 1989, 1990, 1992). In this way
Giles could dismiss arguments against the validity of Celestine's
abdication without admitting the possibility that the pope can be
deposed, e. g., by the Council, as Boniface's adversaries
maintained.




Much better known than *De renuntiatione* is Giles' *De
ecclesiastica potestate*, a treatise also composed in defense of
Boniface VIII. Most probably in 1302, Giles systematically expounded in
this work the views on the relationship between *regnum* and
*sacerdotium* he had already put forward in a re-discovered
sermon held at the papal curia (Luna 1992, Lambertini 2006). The main
tenet of his fully fledged argumentation is that the pope, supreme
authority of the Church but also of the whole of mankind, is the only
legitimate origin of every power on earth, be it exercised -- as
jurisdiction -- on persons, or -- as property -- on
things. In his plenitude of power, the pope possesses an absolute
supremacy both in the ecclesiastical and in the temporal sphere, and
delegates the exercise of the temporal "sword" to lay
sovereigns only in order to fulfill most properly his higher religious
duties. Any authority that does not recognize its dependence on the
papal power is but usurpation. In Giles' view, there is no space even
for a partially autonomous temporal order. Coherently, Giles maintains
that no property rights are valid if they are not legitimated by papal
authority. Interestingly enough, such a claim is also supported by
his account of the origin of property, according to which property is
not a natural institution, but only the consequence of human
agreements, which lack any legitimacy unless they are recognized by
the supreme religious power (Miethke 2000, Homann 2004, Kruger
2007). Scholarly discussion about *De ecclesiastica potestate*
is still open. Karl Ubl (2004) argues with strong arguments against
previous assumptions, that Giles wrote in reaction to John of
Paris' *De regia potestate et papali*. While previous
scholarship stressed the affinity in form and content between *De
ecclesiastica potestate* and the famous Bull *Unam
sanctam*, Francisco Bertelloni (2004) holds that one should not
overlook profound differences between the concepts of papal power that
inspire the two texts.