## 1. Place and Division of Natural Philosophy



Natural philosophy, according to Averroes (following Aristotle),
embraces the study of all sensible beings that undergo change and
possess the principle of motion and rest in themselves (LC 1G
Proemium). The philosophy of natural beings divides into various
branches, for instance, psychology or astronomy. Physics is the first
and most important branch and since it is scientific knowledge physics
has to inquire about causes, and its distinctive causes are "the
causes common to all natural entities" (LC 1G). Averroes follows
Aristotle and distinguishes four causes--matter, form, purpose
and agent--in all natural beings. Physics extends the inquiry on
matter and agent to their outmost limits, that is, Prime Matter and
the First Mover. Another part of philosophy deals with primary form
and first purpose, and this is metaphysics. Averroes adds other
aspects to the subject matter of physics, he calls them
"accessories", "necessary concomitants"
(*lawahiq*, *consequentes)* or properties
common to all natural beings, namely place, time and the like (LC 1GH;
MC 434AE).



However, an important distinction between Aristotle and Averroes is
found in the latter's approach to the value of natural
philosophy. Averroes follows the arrangement that Andronicus made of
Aristotle's writings and, therefore, after the propaedeutic
study of logic, the study of philosophy begins with the physics in the
proper sense of the term. In addition, he remarks that physics belongs
to the theoretical dimension of philosophy and that philosophy has a
practical dimension too, namely ethics. The practical sciences have
taught that "the perfect acquisition of the theoretical sciences
brings man to his ultimate perfection and entire essence" (LC
 1H)[1].
 It is the only way man can attain true happiness.



The natural order requires man to cultivate the ethical virtues,
justice, temperance, courage, etc., after he really possesses the
speculative virtues. Averroes adduces Alexander of Aphrodisias's
preface to his commentary of the *Physics* to support his
statement. Alexander's commentary is lost and, although Marwan
Rashed has published the extant scholia of it, they are limited to
explaining Books IV-VIII (Rashed 2011) and no hint concerning
the content of the preface is given. Our only source is therefore
Averroes' account:



Alexander explained there the reason why the natural order requires
man to be morally virtuous in order that he becomes intellectually
perfect. Once the sage is aware of the infinity of time and his
individual finiteness, he has no fear, and moreover, once he knows
that death afflicts him because of his bodily component, "*ex
necessitate materiae*" (LC 2A) and that he is not going to
be deprived of the intellectual perfection he has acquired, he has no
fear of death, and some sages, like Socrates, have even preferred
death to life because his country did not allow him to go the way of
perfection.



> 
> 
> The sage wants to be morally virtuous because he knows that both
> virtues, moral and theoretical, are inseparable. He knows the nature
> of justice existing in the substance of [created] beings and he
> aspires "to be similar to this nature and to acquire its
> form". (LC 2C; cf. Harvey 1985: 66: 21-23)
> 
> 
> 



Similar views are expressed in Averroes' Short Commentary:
Natural philosophy has a twofold dimension: it is knowledge of the
material world and a speculative science but it is also essential in
contributing to the happiness of those who possess this knowledge. (SC
Variant reading to 7:8-8:12), although he later replaced the
text with another of technical character.


## 2. Four Causes and Three Principles



Aristotle stated the four causes--form, agent, purpose, and
matter--but he also added three principles, form, matter and
privation in *Phys.* I.7-9. In 190a13-21 Aristotle
stressed that in all cases of coming-to-be there must be something
that underlies change, Averroes extensively comments on the need for a
substrate and observes:



> 
> 
> Aristotle and all the Ancients agree that nothing comes to be out of
> nothing, and I have seen some colleagues (*socii*) doubting on
> this question, but I entered into this in the treatise *On the
> Substance of the Universe* to some extent (LC 36E TC60).
> 
> 
> 



The treatise *On the Substance of the Universe* is not extant
in Arabic, but the Latin and the Hebrew translations are, as A. Hyman
explains (Hyman 1986, 13-15). Averroes reminds that
"modern thinkers", i.e., Muslim theologians, have been
insisting that coming-to-be does take place out of nothing because of
the 'custom' of saying it again and again, and bad
'custom' has destructive effects. These theologians
contend that one who first learns philosophy is then not capable of
learning the religious law and that the other sciences are hidden to
one who has learned the Shari`a (LC 36F TC60). Since
Averroes' colleagues hesitate, he wants to clear up their doubts
and wants to comment on Aristotle's arguments. *Phys.*
190b5-10 describes the various ways of generation and concludes
that all need a substratum, an underlying matter. Averroes who
explains that the logical procedure followed here by Aristotle is
induction--reasoning from the particular to the
general--concludes: "It is clear that coming-to-be
necessarily requires a subject not only in natural but also in
artificial things" (LC 37L TC63). This subject is numerically
one and does not have any substantial characteristic
(*dispositio*) but can receive all kinds of substantial
characteristics:



> 
> 
> It is called first matter, and first *hyle*, and it is evident
> that this matter is
>  <not>[2]
>  deprived of corporeity because if it was, it would have a substantial
> nature, a name, and a definition. From this it appears that he who
> affirms that this nature (sic, *natura*) is a body, is wrong,
> and he is likewise wrong who establishes that which has dimensions as
> a subject possessing form in actuality, as Avicenna believes (LC 38D
> TC63).
> 
> 
> 



No doubt Averroes is referring to the "corporeal form" of
Avicenna. Since Prime Matter is a metaphysical notion and as such
nothing empirically verifiable, questions arose about its kind of
existence. The Greek commentators developed the concept of corporeal
form, which Avicenna maintains mainly in his physics. The corporeal
form, *sura jismiya*, invests Prime Matter with
corporeality and dimensions. Averroes, however, considers corporeality
an attribute, not a form (SC 14: 10-11) and here in the LC he
rejects the doctrine of the corporeal form.



The LC is concerned with the distinction between Prime Matter and
privation. The bronze, matter, can become the statue, form, because it
is not the statue and this negation is a third principle. Aristotle
distinguished between absolute non-being and accidental not-being, and
so matter is non-being accidentally, while privation is not-being
*per se* (*Phys.* I.9, 191b34-192a5). In his
interpretation of the Aristotelian passage, Averroes points to the
privation of form as the nature of matter. Prime Matter is
"almost composed of being and not-being" (LC 45C TC80).
Because of the presence of not-being in material beings, coming-to-be
and passing-away is possible in them but not in heavenly bodies which
do not have matter, "as was explained in the treatise *On the
substance of the universe*" (LC 45CD).



The Middle Commentary also deals with privation (MC 439K-440I;
MC Kalonymos L 13vo-15ro) and insists on privation
being a principle. Averroes indicates that the nature of Prime Matter
is different from that of privation



> 
> 
> for privation does not belong to the nature of coming-to-be in such a
> way that it becomes part of the generated thing but it is only some
> accident to the subject which is a [constituent] part of the generated
> thing. But it is necessary for coming-to-be and therefore, it is
> accidentally called principle. (MC 440E; MC Kalonymos L
> 14vo7-9)
> 
> 
> 



Incidentally, it should be observed that in the SC Prime Matter is
seen as containing all forms "in potentiality and
possibility" (SC 15:7). The distinction between
*quwa* and *imkan* is not explicitly present
in Aristotle, where we only read *kata dynamin* in the related
text (*Phys.* 192a26), although he sketches the distinction in
some passages of *Metaphysics* IX. However, the distinction is
well known to Avicenna. In his *Shifa'*,
*Metaphysics* IV.2 (Avicenna, *Metaphysics*, IV.2,
130-143), Avicenna explains the notions of potentiality and
possibility in detail; Avempace also makes the distinction in his
commentary on the *Physics* (Avempace [SST], 28: 21-30,
10). The LC and the MC do not refer to the distinction, and the
absence may be explained because Avempace's influence loses
weight in Averroes' later 
 stages.[3]


## 3. Nature and Human Form



At the end of his Long Commentary on Book I, Averroes distances
himself from Avicenna in so far as the latter maintains that
Metaphysics has to prove the composition of matter and form in any
body. Averroes claims that only the observation of changes in the
substance can explain the existence of these two principles (LC 47H
TC83). He is not quoting Avicenna in an exact way, so he may not have
had Avicenna's books of the *Shifa'*,
"The Healing", at hand. However, he is right in the
interpretation, since Avicenna states that the subject matter of
natural philosophy is the body as such, not the condition that it is
composed of matter and form (Avicenna, *Metaphysics*, I.2,
7).



Avicenna affirms also that the natural philosopher is not allowed to
address the question of Nature as a principle but has to receive it
from the metaphysician (Avicenna, *Physics*, I.5, 39-40).
Averroes, at the beginning of his commentary on Book II follows his
Master Aristotle and defines Nature as "principle and cause by reason
of which that in which it is changes [primarily and *per se*]
and by reason of which that in which it is rests primarily and by
itself" (LC 49B TC3). Aristotle's definition in *Phys.*
192b21-23, reads perhaps more clearly: "Nature is the principle
and cause of motion and rest in that in which [Nature] inheres
primarily and by itself, and not accidentally."



According to Averroes the existence of Nature is self-evident as well
as its definition; the metaphysician does not have to prove it. He
disagrees with Avicenna who seemingly contended that Nature belongs to
the class of things that are not self-evident and that the definition
above is not known by itself; for this reason the metaphysician should
have to explain what Nature is. Averroes is not sure about what
Avicenna said and he admits that the metaphysician is qualified to
refute those views denying the existence of Nature as a principle. He
guesses that Avicenna was moved to this view "because [Aristotle] had
explained in Books VII and VIII that every movable has a mover, and
there is no doubt about it except for the four elements" (LC 49B).



They move by themselves but mover and movable are different in them
(see below SS 12), and Avicenna would falsely understand that
Aristotle had not explained it in physics so held that the
metaphysician had to do it.



Is Nature a material or formal cause? Aristotle said that some of his
predecessors, and he names Antiphon among them, held that Nature was
solely a material cause, and not a formal cause; they would say that
Nature is fire, earth, air or water (*Phys.* II.1,
193a12-26). Alexander of Aphrodisias, according to Averroes,
added that they also did not know that Nature "was different
from the other accidents" (LC 51G TC8) and Averroes joins his
view. Nature is not only matter but form too, and it better deserves
to be form because form is in actuality as Nature is (LC 52G
TC12).



Within the context of Nature as form and "inasmuch as privation
is a kind of form" (*Phys.* II.1, 193b18-21),
Averroes insists on a twofold division of form: there are perfect and
imperfect forms. Perfect forms are free from privation, while
imperfect, *diminutae*, forms contain some kind of privation
(LC 53G TC15). In the example of blackness becoming whiteness,
whiteness is perfect form since there is no privation inherent it, but
blackness is not, since the privation of whiteness inheres it. Form
has these double aspects in all contraries existing in qualitative
changes. In the case of substantial changes--the generation of
water out of air would be one example--doubts arise since
contraries are apparently not existent.



Averroes recalls that privation exists in Prime Matter and thinks that
Aristotle "perhaps wanted to say that form is predicated in both
aspects of the disposition and privation existing in Prime
Matter" (LC 53H TC15). Privation existing in Prime Matter is not
absolute privation and Averroes adds a gradation: *quodammodo*,
"in a certain way" because this kind of privation is
"like the form of matter" (LC 53I) that never deserts
matter. Averroes tells us that Aristotle will inquire later about the
issue in the Book *De generatione et corruptione*, and Book II
of the Aristotelian *Coming-to-be and Passing-away* explains
the composition of the four elements, the forms of which are the
primary contraries, i.e., the four primary qualities (Averroes [SC
GC]: 27). Averroes anticipates his own conclusion: The kind of
privation existing in Prime Matter is such that it is never
dispossessed of the primary contraries (LC 53K TC15).



Nature is form, and perfect form, but "inasmuch as privation is
a kind of form" Nature is affected by the kind of privation
existing in Prime Matter, in such a way that Nature can be considered
an imperfect form. This seems to be Averroes' interpretation of
*Phys.* I.1, 193b18-21 concerning the two kinds of
perfection.



Averroes follows Aristotle who asserts that the philosopher of Nature
also has to inquire about the purpose and the means needed for this
purpose (LC 57EH TC23; *Phys.* 194a29-30) and
reformulates Aristotle's reasoning in a syllogistic way: "Nature
is the last of the motions of coming-to-be, but it is nobler than the
foregoing ones; Everything in this manner is purpose, *ergo*
Nature is purpose,"and he distinguishes it from death that is solely
end.



We had read that the philosopher of Nature is concerned with Prime
Matter, but "since matter belongs to the genus of
relation", i.e., it depends on its relation to form (LC 58K
TC26; *Phys.* II.2, 194b9), its study also involves the study
of form. Averroes mentions that matter exists on account of form,
*propter formam*, and that the philosopher of Nature
investigates both. He investigates form *per se*, and matter
because of form (LC 58L), but the issue of how far his research can go
arises. The philosopher of Nature searches for form and
 quiddity[4]
 and goes as far as to the last, or highest form on the account of
which matter exists, and this is man's form, *forma
hominis* (LC 59A TC26). Averroes is very assertive and once again
he disagrees with Avicenna when he claims that only the metaphysician
deals with these forms. For Averroes, the metaphysician studies the
abstract forms, i.e., existing without matter, while the philosopher
of Nature, the material forms but also the human form which is an
intermediate between them and the purely abstract forms (LC 59D).


## 4. Nature against Fortune



Chapter 3 of Aristotle's *Physics* II is a treatise on
the subject of the four causes and it corresponds almost entirely to
*Metaphysics* V.2. Then chapters 4 and 5 examine the question
of chance and incidental causation, i.e., spontaneity. The question is
related to whether Nature acts with purpose and Averroes sees its
great significance. Commenting on 196b10-17, Averroes enters
into a discussion with Avicenna on the status of two irregular kinds
of causation, *fortuna* and *casus*, chance (LC f.
66D-67D TC48). In the Arabic translation of the *Physics*
they were *bakht* and *min tilqa' al-nafs*
(Aristotle, *Tabi`a* [1964: 111: 4-5]),
and in Averroes' short commentary, *bakht* and
*ittifaq*, respectively (SC 26: 19). Averroes formulates
the Aristotelian argument in the form of a conditional syllogism the
conclusion of which is that spontaneous causation happens in things
that are possible only in a few cases, *in minori parte*.
Avicenna argues that the same action can be necessarily caused in some
beings and accidentally in some others and that, in a similar way, the
action can be possible for some beings in most cases and for some
others in the least cases. Averroes gives an example of walking and
resting. According to Avicenna, walking is accidental from the point
of view of the moving power, but it is necessary from that of the
desire.



In Avicenna's metaphysics necessity pervades everything, so that
we should agree with Averroes' view that for him "all
[actions] are necessary by
 nature",[5]
 (LC 66M). Averroes affirms contingency and points out that Prime
Matter is prepared to receive two contraries in the same way but that
efficient causes act differently. Any contingent action does not
correspond with two efficient causes "contrary in the same way
and at all the time". Averroes objects that if any efficient
cause would equally act or not act, then the whole of Nature would act
without any rule, that is, in vain, *ociose*, a result that
neither Aristotle nor Averroes accept. The following quotation
illustrates Averroes' thought:



> 
> 
> When we say that in Prime Matter the potentiality (*potentia*)
> for being is the same as the potentiality for not being, we mean that
> two contraries exist in it at the same opposite times, as for example
> rain can be and not be, but here in the winter, and here in the
> summer, and that the causes equally producing these two contingent
> [facts] must be alternating at equal times, [but] the action of those
> [causes] takes place generally, and [the causes] are the celestial
> bodies, and consequently they are causes of that which exists just as
> of that which does not exist. (LC 67BC TC48)
> 
> 
> 



Averroes solves the conflict in an original way, he ranges Prime
Matter and passive potencies against efficient causes and active
potencies. Passive potencies are in principle indifferent to a certain
action and they are the reason why contingent actions may take place
or not likewise. Active potencies, on the contrary, follow rules so
that their actions are not equally contingent but usually happen. A
further distinction between essential and accidental causality helps
him to explain generally and rarely occurring actions (LC 67GK TC49).
Under another aspect, the agent, or efficient cause, necessarily
produces the effect in the case of eternal beings and generally does
it in the beings that come-to-be (LC 75D TC74).



The philosopher of Nature enquires about Nature and about the four
causes, and we have known the material, formal and efficient causes,
but does Nature act for a purpose? Aristotle starts *Phys.*
II.8 saying that he is going to prove that Nature belongs to the final
causes (198b10-15) and Averroes observes that this tenet is a
basic principle in Physics and Metaphysics (LC 75L TC75). If the
philosopher of Nature would deny the existence of purposiveness in it,
the other causes would be annulled. Matter exists on the account of
form, we have read. Form exists because an agent impresses it on
matter, and the agent acts because it wants to achieve an end. And "if
the metaphysician would not admit [the principle of purposiveness] he
would be unable to prove that God has solicitousness for those
[beings] that are here." (LC 75L)



Aristotle mentioned Zeus in *Phys.* II.8, 198b10-32 but
to deny that he produced rain in order that crops grow; rain happens
out of necessity. Since Averroes read God instead of Zeus in the
Arabic translation available to him (*Tabi`a*
[1964: 144:
 3])[6],
 and he also used the word in his comment on the first passage (LC
76H-77B TC76), it is remarkable that he did not see divine
providence assailed by that claim. Averroes saw no difficulty in
Nature acting here with purpose, and he placed God in a rank higher
than just making rain fall. For him God acts as final cause and the
order of Nature reveals the presence of His intelligence.



Aristotle argued that there is purposiveness in the natural as well as
the artificial realm concluding that "it is obvious that Nature
is a cause, and one directed towards an end" (*Phys.*
II.8, 199b32-33). Averroes agreed and opposed those who claim
that purposiveness exists only in deliberative actions because arts
act externally while Nature acts internally. He notes that not all
arts are deliberative and that the physician is capable of using the
art of medicine to heal himself, he is not external to the action (LC
81I-82A TC86).


## 5. Absolute or Conditional Necessity in Nature



Purposiveness and necessity are interrelated and Aristotle analyses
the matter in *Phys.* II.9, introducing the distinction between
absolute and conditional necessity. Conditional necessity is always
subject to achieving an end. A well-known instance is given by
Aristotle in 200a10-15: a saw must necessarily be made of iron
to do its work. The material, iron, is necessary but does not lead to
the production of a saw. Purpose precedes deliberative actions and
imposes necessity upon the materials. As for natural events, Aristotle
only says: "necessity in the natural [events] is limited to what
is called their matter and their motions" (*Phys.* II.9,
200a30-32), not to the results, and the question arises whether
necessity is absolute or conditional.



Averroes pays attention to the division between that which results
from an intended action and that which results from having a certain
matter. He quotes Alexander of Aphrodisias, whose commentary on the
*Physics*, as already noted, is not extant: "Those [causes]
that are before the purpose in something (*in re*) are not said
to be cause of the purpose except in the way that matter is cause of
the purpose" (LC 82M TC88).



We know that Alexander had to defend the Aristotelian position against
the Stoics in such an important matter as destiny or fate. In his book
*On Destiny* Alexander admits fate in Nature but not as
governing human acts. While the final cause appears in planned changes
as external to them, "the creations of Nature have the principle
and cause of such generation within themselves" (*De
fato* 168). Alexander's treatise *On Providence* was
well known to Averroes who paraphrased part of it in his "Short
Commentary on the Metaphysics", as R. Arnzen has proved (Arnzen
2010: 331-335). This is the context within which we may
interpret the short quotation Averroes makes of Alexander and Averroes
ends it adding "purpose is indeed the main cause" (LC 83A
TC88).



Averroes also reflects upon necessity of that which follows matter.
One example is death which is necessary for animals as a consequence
of their matter. Is this an absolute necessity? Averroes denies it,
pointing out that these instances of necessity are caused by the
substantial form or essential definition of the beings, here the
animals. Averroes claims that both cases of necessity--according
to matter or according to purpose--have conditional characters
since "they are because of the form and essence
(*definitio*) and they are not unconditionally necessary"
(LC 83C TC88).



Averroes finally reflects on absolutely necessary, which seemed to be
excluded by Aristotle in the passage. Whenever we ask for the reason
of products of Nature or of the arts, the answer we get is their final
cause, for instance, why does a saw have sharp teeth? To cut wood. The
answer however is completely different in the case of the eternal
beings. An eternal being acts because of its essence, its activity is
because of itself, *propter ipsum*, and necessity is
unconditional (LC 83F TC88).


## 6. Change or Motion



In Book III Aristotle defines motion once as "the perfection of
that which is in potentiality under the aspect that it is in
potentiality" (201a10-11) and another as "the
perfection of that which is movable under the aspect that it is
movable" (202a7-8). Before reaching the first passage,
Averroes distinguishes four premises in Aristotle's approach to
defining motion (LC 86H TC3; *Phys.* III.1,
200b25-32):


1. Being divides into actual and potential being
2. All beings belong to [at least] one of the ten Aristotelian
categories, *praedicamenta*.
3. The category of relation embraces the relation between more and
less, as well as the relation between agent and patient.
4. Motion occurs in more than one category (LC 87A TC4).



Based on the evidence of four propositions, Averroes realizes that
motion does not have a univocal definition. Motion belongs to the
genus of the perfection toward which it intends, thus motion in
substance belongs to the genus of substance, motions in quantity,
place and quality to the respective genera. But insofar as transition
towards a perfection is different from the perfection itself, motion
is something different from its goal and Averroes affirms that,
considered in this way, "Motion must be a genus per se, for the
way toward something is different from it [the end]",
*necesse est ut sit genus per se*, *via enim ad rem est
aliud ab ipsa re* (LC 87D TC4). For this reason he believes,
Aristotle classified motion in own category in his book on the
*Categories*, and as we will see below, the category is being
affected, *passio*.



Averroes remarks that the definition of motion as belonging to the
genus of its perfection, is more adequate, *verior*, although
the definition of motion as a genus in itself, is better known,
*famosior.* In the *Physics* Aristotle deals accordingly
with the first definition, Averroes points out (LC 87E TC4). Medieval
Latin philosophy would call this view of motion as genus in itself
"a flow of form" *fluxus formae*, and the contrary
view, "a flowing form", *forma fluens* (Maier 1958:
62-64).



Averroes comments on the definition of *Physics*
201a10-11: "motion is the perfection of that which is in
potentiality under the aspect that it is in potentiality" (LC
87D, *secundum quod*) and says that the movable has two kinds
of perfection, a perfection in actuality, and a perfection in
potentiality, under the aspect of which it is called motion.
Themistius elaborated on the distinction (CAG 5.2: 69:9-70:31 )
and Philoponus emphasized it in his commentary (Philoponus, CAG 16:
342:10-344:7). Averroes could have received it either from
Philoponus (Lettinck 1994: 213) or Themistius (see above). He observes
that the definition is valid for both eternal and non-eternal classes
of motion and he anticipates that the continuity of motion results
from the definition itself (LC 88A TC6).



As for the definition of motion in *Phys.* 202a7-8,
"perfection of that which is movable", Averroes finds that
it is more evident but that of *Phys.* 201a10-11,
"perfection of that which is in potentiality" effectively
targets the substance of motion, *demonstrat magis substantiam
motus* (LC92A TC16).



In the Middle Commentary the premises for defining motion are
three:


1. Natural beings are sometimes in potentiality, sometimes in
actuality and "that is common to all ten categories";
2. Motion belongs to the category of relation
(*histarphut*);
3. Motion is said by analogy (MC 449G-I; MC Kalonymos L
28ro19-28vo8).



The definition of motion presented there is the *verior* one,
i.e., motion belongs to the genus of its perfection, and it is not a
category in itself.



Since any change or motion requires two elements, the agent or mover
and the patient or movable, Aristotle raises the question whether
motion is in the mover or the movable (*Phys.* III.3). Averroes
gives following explanation: the mover acts in so far as it is form,
that is to say, in so far as it is in actuality, and the movable is
moved in so far as it is in potentiality, therefore the motion
"becomes the same perfection of both of them" (LC 92H
TC18). Nevertheless, they are two kinds of perfection and Aristotle
saw here a dialectical difficulty (*aporia logike*,
*Phys.* III.3, 202a21) with which Averroes deals at length (LC
93F-94B TC19) but for Averroes the double character is no
difficulty: motion is one and the same according to the subject,
different according to the definition (LC 94K TC21).



Motion in place is one kind of change but it is prior to the other
kinds, to change in quality or alteration, to change in quantity or
growth and decrease, and to change in substance, or coming-to-be and
passing-away. Within local motion circular motion is the most perfect
form and we will see how the universe is moved by circular motion.


## 7. Infiniteness



At the beginning of Book III, Aristotle had linked the issue of motion
to that of the continuous but also to that of the infinite
(*Phys.* 200b16-18) because the continuous can be divided
without limit. Averroes commented there that the advocates of atoms,
i.e., the thesis that bodies are composed of a limited quantity of
indivisible parts, would not agree with the definition that
"continuous is that which divides into infinite". He
added:



> 
> 
> Maybe [Aristotle] said so because continuous can have another
> definition, like as that saying that "the continuous is that in
> the middle of which a common bound to two parts can be
> established". (LC 86A TC1; cf. *Categories*
> 5a14-15)
> 
> 
> 



The infinite can be seen under various aspects including intellects
and geometrical extensions, but the philosopher of Nature has to
enquire only about the infinite "which concerns the extensions
that are in matter" (LC 102K TC39). He realizes that there is
neither continuous nor discrete infinite actually existent. The
infinite can only exist in potentiality.



Further Averroes agrees with Aristotle that spatial extension can be
divided *in infinitum* which does not mean that it actually
happens. For the possibility of an infinite by addition, Averroes
echoes al-Farabi's and Avempace's
commentaries while explaining the passage 206b16-26 (LC
113H-114G T60).



> 
> 
> If we would affirm an endless decrease (*diminutio*), it would
> be not impossible because decrease is going towards nothing (*ad
> nihil*), the cause of which is matter; addition is going towards
> being, the cause of which is form, infinity exists because of matter,
> as finiteness does because of form. (LC 114B).
> 
> 
> 



Averroes disagrees with al-Farabi and Avempace who held
the view that just as the geometer can always draw a longer line
*in infinitum*, so a magnitude can always grow larger. For him
there is a major difference between the geometer and the philosopher
of Nature who can conceive infinity in addition only by means of
addition of finite quantities, and so interprets Aristotle.
Imagination is responsible for the misunderstanding (LC 120IK
TC75).



Adding and deducting finite magnitudes is true in potentiality, but an
increasing or decreasing of a whole is not possible, neither
potentially nor actually. And Averroes does not comment on
Aristotle's words that time, motion, and thought must be
considered infinite (208a20-21), and he only remarks "the
infinity which is found in them is not stable, i.e., existing in
actuality, and that is impossible, but it is successive" (LC
121A TC75).


## 8. Place



Aristotle holds that place is something but it is neither form nor
matter. He gives several reasons against place being either of the two
and argues, for instance, "If a thing's place is in the
thing (as it must be if it is either its form or its matter), place
will be in place" (*Phys.* IV.2, 210a5-6) and the
result is absurd. The passage causes Averroes to depart from the
subject and he first considers the following propositions concerning
place:



> 
> 
> First, form and matter move by means of the body composed of them
> both. Second, in so far as they move, they need to be in place. Third
> if one of them is place, place must be in place. The second and third
> propositions are true, the first is not. (LC 129B TC20)
> 
> 
> 



Averroes reminds us that in Book VII, Aristotle says that the proper
subject of change and motion is body, not its matter or its form.
Matter and form are in place accidentally and "it is not
impossible that place is in place accidentally, *per
accidens*" (LC 129C). What is accidental divides into two
categories, always accidental or rarely so. Matter and form always
move together with the body, therefore place belongs to the category
of always accident, and if it is constant, place is in place all the
time, but it is obvious that place is not always in place, either
essentially or accidentally. The argument makes an exception: the
place of the outermost body, the place embracing the last body,
because it moves together with the outermost body, and in this case it
is in place accidentally and *raro*, rarely (LC 129E).



Alexander of Aphrodisias objected because place is related to
quantity: Place is equal to the thing that it contains. If a body
moves, it moves into a place that is equal to it, and for this reason
form or matter are in place essentially. Alexander's commentary
on the *Physics* has not reached us, and we have to rely on
Averroes' account. He admits: "that which Alexander said
is not free of doubt" (LC 129F).



Later on (LC 133H TC30) Averroes refers again to Alexander; he
comments on *Phys.* IV 210b31-211a6, and makes five
statements concerning 'place' that he considers to be
Aristotelian:


1. Place contains what is in place and is different from it;
2. Place is equal to what is in place;
3. Place is separate from what is in place, and Averroes quotes
Aristotle: "it is also devoid of any kind of particulars and is
separated from them", *extra quodcunque singularium, et
separatur ab eis*;
4. Above and below are the directions of place;
5. Place is that toward which what is in place naturally moves.



According to Averroes, Alexander read in statement 3: "It
[place] is *not* devoid of any particulars and is
separated", instead of the affirmative sentence "It is
also devoid of any particulars and is separated from them" (LC
133H). Averroes should have read Ishaq Ibn
Hunayn's translation. The Arabic translation of
Ishaq reads here "[Place] is devoid of any aspects
and it is separable" (Aristotle, *Tabi`a*
[1964: 302: 9-10]), and it coincides with Ross' edition
(*apoleipesthai ekastou*, 211a2; [Ross 1936]). Averroes thinks
that Alexander's reading is "more true, but it is not
known *per se*", and that Alexander would choose this
reading to oppose those who pretend the place to be the void.



Since place is neither matter nor form nor extension,
*dimensio*, i.e., an extension that is always independent from
that of the movable, Aristotle concludes that place has to be the
limit of the surrounding body (*peras tou periekhontos
somatos*, *Phys.* IV.4, 212a2-6). Place does not
move essentially, and Averroes says that Aristotle gave a renowned
argument, *rationemfamosam*, to support his tenet (LC 140F
TC42; *Phys.* 212a21-30). The surface surrounding the
last sphere of universe is the absolute above, and the center of the
universe, i.e., the earth, the absolute below and just as the center
is stable, the outmost surface is too; they cannot move at all.
Averroes adds that the air is above and the water below "but not
absolutely", since Aristotle could mention fire also, as being
light. The argument can be organized as a syllogism of the second
figure, and two affirmative propositions: "The highest [body] has to
be stable, *fixum*; the outermost circulating [body] is stable;
*ergo*, the highest [body] is the outermost circulating" (LC
140G).



1) Averroes now faces a great question, *magna quaestio*, in
relation to *Phys.* IV.5, 212a31-b3, a passage where
Aristotle mentions the circular motion in the universe (his
commentary, TC43, occupies LC 141C through LC 143C). We know that the
outermost sphere moves with the daily rotation but "as a whole
it does not simultaneously change its place, though it moves in a
circle: for this place is the place of its parts". Only their
parts, the four elements, change place (*Phys.* 212b1). For
this accidental reason, Aristotle grants it some kind of place. The
Aristotelian passage remained obscure and discussions about the place
of the universe arose.



Averroes expresses the dilemma: "We have the choice between either of
two options: either we affirm that something moving is not in place,
or we affirm that place is the void, and it is extension" (LC 141F
TC43). Averroes mentions the views of John Philoponus (d. 570 CE) and
Themistius (d. 387 CE). For Philoponus, the solution to the dilemma
consisted in taking place as extension, *dimensio*, and
accepting the existence of the void. Averroes seems to have had access
to Philoponus' *Corollary on Place*, the Greek original
of which is extant (Philoponus CAG 17: 557-585) and has been
translated into English (1991). We will see below that Averroes
rejects the existence of the void.



2) For Themistius, the celestial body is in a place "not in
accordance with the whole but with the parts" (*secundum
partes*, LC 141F TC43), and Averroes explains that "It means
in accordance with the spheres that the largest sphere
contains", and we should understand that Themistius skipped the
five elements. Averroes interprets that the latter is the sphere of
the fixed stars, which is not surrounded by anything else and the
concavity of which surrounds everything. Moreover he refers to the
"natural science" of his time that proved that there is a
ninth sphere, the one of the daily motion, and if so, we can affirm
that the motion of the latter is "the essential motion of the
whole universe, *orbis*" (*essentialiter*, LC 141H
T43).



3) The *magna quaestio* is many-sided. Averroes recalls a
passage in *Physics* VI, 240a29-b7, where Aristotle
refuted Zeno's fourth argument against motion and asserted that
the sphere moves in accordance with the whole as well as with the
parts. Therefore, if Themistius claimed that the sphere is in place
not in accordance with the whole but only with the parts, because he
thought that only its parts change place, he would contradict
Aristotle's views (LC 141I).



Averroes says that Themistius could argue that Aristotle in
*Physics* VI meant the same as here in *Physics* IV,
i.e., that the sphere does not change its place as a whole
(*Phys.* 212a35). Averroes restricts the assertion to the
spherical body of the universe. Other spheres move because of their
parts, which change their places, and the parts are all the celestial
bodies:



> 
> 
> When he said "but it can move in a circle" (*alio modo
> movetur circulariter* 212a35-b1) he meant that the circular
> motion is predicated of the whole because of certain of its parts,
> i.e., the celestial bodies, in the same manner as rectilinear motion
> is predicated of them because of the motion of the elements, which are
> also some parts of them. (LC 141K TC43)
> 
> 
> 



Themistius interpreted that since Aristotle said that the heavenly
body (*coelum*) is in place *per accidens*, he assumed
another heavenly body to be in place (I add, *per se*) and
Averroes explains "another heavenly body" as all celestial
spheres, *orbium*. According to Themistius, *per
accidens* is such a wide category that the commentators before him
did not find the term adequate and they said the heavenly body to be
in a place because of its parts. Themistius and Averroes share the
view that Aristotle here was using the term *per accidens*
freely (LC 141M). Themistius is a highly regarded authority but
Averroes will formulate his own solution.



According to Aristotle--so he understands him--the
rectilinearly moving bodies are in place *per se*, essentially,
the rotating bodies, accidentally, *per accidens*, and the
whole universe is in place because of its parts, and parts mean the
five elementary bodies (LC 142CD TC43). But before reaching his
conclusion Averroes has to clear the way refuting Avempace's
doctrine:



4) Avempace (d. 1138) had his own view on the issue. The sphere is not
in place because nothing encloses it from outside. "The place of
the sphere that is envisioned by this, in so far as it is sphere, is
the convexity of the center, around which it rotates" (LC 142A
T43). Avempace would take Aristotle's definition of place as
that which surrounds the body and apply it to the external surface of
the bodies moving rectilinearly and to the internal surface of the
bodies rotating. Averroes conjectures that Avempace borrowed his view
from al-Farabi (d. c. 950) who refuted the opinions of
Joannes Philoponus on place but al-Farabi's book
"did not fall into our hands", he says.



Averroes expounded Avempace's view in the Short (SC
53:10-56:10; Lettinck 1994: 316), and the Middle Commentary at
length (MC Kalonymos L 45vo22-47ro23) but he also
refers to it in the LC where he rejects it because Avempace
"abandoned Aristotle's discourse and erred heavily"
(LC 142K TC43). Avempace and al-Farabi should maintain
that the sphere is in place essentially, and Averroes'
summarizing words in the MC may be worth of being translated:



> 
> 
> What we told about place of the sphere is that which Abu Bakr Ibn
> al-Sa'igh and Abu Nasr
> [al-Farabi] before him, considered, i.e., that its
> parts are in place essentially, i.e., by means of its center. Place is
> said by equivocity with regard to the place of the spherical body and
> to the place of the body [moving] in straight lines. Indeed, it
> appears [to me] that it is most reasonable to say that the sphere is
> in place accidentally by means of its center which [the sphere]
> surrounds because what is in place essentially is surrounded, not
> surrounding. But that which surrounds matches (*maqbil*) to
> that which is surrounded. It may be said that which surrounds is
> **in** that which is surrounded. Since the body of the
> heavens does not have anything surrounding it, it is not in place
> essentially, but it is in place by means of that surrounded by it, and
> this is accidentally. (MC Kalonymos L 47ro2-10; O
> 37vo-38ro)
> 
> 
> 



5) Averroes disagrees with Avempace and he still has some reflections
on the *magna quaestio*. He explains that the rectilinearly
moving bodies are in place essentially, the rotating bodies,
accidentally, and that the whole universe is in place because of its
parts, as said before (LC 142CD).



He states: "That which is in place is equal to the place"
(LC 142D TC43; cf. *Phys.* IV.4, 212a29-30). This means,
in its proper sense, that the contents of both have to be equal, but
the surface of the concave sphere is not equal to the surfaces of the
embraced spheres. Averroes refers to their content, and says
"that equality is impossible, unless place were the void"
(*ista aequalitas non est vera de loco, nisi inane esset*, LC
142E TC43). Averroes looks for an answer. The universe is at rest as a
whole. The earth is the center of the universe and the center is at
rest, and it is in place essentially. The heavenly body
(*coelum*) is not at rest in so far as its parts, i.e., the
various spheres, move but it does not translocate, *non
transmutatur*, and for this reason it is in place accidentally (LC
142G T43). His reference is Aristotle, but Bekker's edition of
the passage 212b7-13 simply reads that "some things [are]
in place accidentally like the soul and the heavenly
 body".[7]



If the heavenly body is in place accidentally, *per accidens*,
the following objection could be raised: Is its motion also
accidental? (LC 142K TC43). And if its motion is accidental, since the
motion of the heavenly body precedes all other motions, an accidental
motion will precede any essential motion. Averroes answers the
objection saying that all "that move by themselves need something at
rest, around which they move, as Aristotle says in the Book about the
local motions of the animals," (*De motu animalium*, LC 142L
TC43) but it does not matter whether a body is at rest essentially or
accidentally.



Averroes believes this to be the solution and does understand why
Alexander of Aphrodisias held the view that the sphere of the fixed
stars is not in a place. Besides he thinks that Alexander influenced
Avicenna to deny that the heavenly body is in place and to affirm that
its motion is only "positional", it changes only its
position (*situale*, LC 144H-I TC47). Averroes final
position is read at the beginning of TC44 that comments on
*Physics* IV.4, 212b3-6:



> 
> 
> Some bodies are in place essentially, and they are those outside of
> which there is some surrounding body, and some are in place because
> their parts are in place, and this is the condition of the body of the
> All, and some are in place accidentally, like that which moves
> circularly. (LC 143E)
> 
> 
> 


## 9. Void, Motion in the Void



Aristotle stated the arguments of his predecessors for and against the
existence of the void, then he defined its exact meaning
(*Phys.* IV.6, 213a12-214a16). Afterwards he would refute
the existence of the void by proving that change and locomotion do not
involve the existence of the void (214a16-b11) and that void is
incompatible with motion (214b12-216b26).



The second set of arguments includes his explanation about velocity
and the motion of bodies in the medium (*Phys.* IV.8,
215a29-216a21). Velocity depends on the heaviness or lightness
of a falling body, but also on the density of the medium, water or
air, for instance. The same body will fall at different velocities in
accordance with the ratio of the various media. The role of the medium
is to oppose resistance to any natural or violent motion, but
Aristotle does not see it as a hindrance but as necessarily
complementing the action of the moving agent. The void has no density
and since there is no ratio in which it stands to a body, motion would
happen within any imaginable time.



Philoponus disagreed with Aristotle and affirmed the existence of the
void and the possibility of motion in it (CAG 17: 675-695).
Centuries later, Avempace denied the role of the medium as being
necessary for motion, and maintained that bodies can move in the void,
but a direct influence of Philoponus upon him has not been proved.
Averroes ignored the issue in the Short Commentary but not in the
Middle Commentary. Averroes organizes the arguments against the
existence of the void in proofs, and the third proof as stated in MC
Book IV, section 2, chapter 5 maintains that if there is no medium
(*emsa<i*), motion will happen in no time, and that
this is not possible. He opposes Avempace's view that the stone
can naturally move in time in the void and that the medium only makes
its natural motion slower; the medium water slows down its fall less
than the medium air does (MC Kalonymos L
52vo20-53ro23). Natural motion has its own velocity
and the medium deducts from it, so that



> 
> 
> If the movable would move in the void (*requt*), the movable
> would be within time because [Avempace] thought that the local delay
> would be removed from it and that its original motion would remain,
> and all this is false illusion. (MC Kalonymos L
> 53ro1-3)
> 
> 
> 



Averroes does not accept the possibility of motion as addable or
deductible and insists in the oneness. In the Long Commentary he
develops the principle. The issue of motion in the void occupies LC
158L-162C T71, and there Averroes expounds Avempace's
commentary making it known to the Latin philosophers, and Thomas of
Aquinas adopted the latter's view. Averroes knows that Avempace
objected that if motion needed a medium so that it happens in time,
the celestial spheres would rotate in no time (LC 160D TC71; Avempace
[SST] 1974, 116: 6-18]).



Averroes blames Avempace for misunderstanding the essence of velocity.
Velocity is not a motion added to or subtracted from another motion,
in this case, natural motion, "like a line added or subtracted
from a line" (LC 161A). For Averroes, there is a ratio between
the power of mover and the resistance of the movable, and a ratio
between the hindering and the hindered, and velocity depends on both
factors. Velocity in the celestial spheres results from the first kind
of ratio, since there is no medium, and Averroes agrees with Avempace
in considering the degree of nobleness (*sharf*) of the various
spheres as the factor explaining their different velocities.
*Sharf* is the surplus of "energy" between the
power of motor and the resistance opposed by the movable.



Averroes disagrees with Avempace concerning the movements of the four
elements. He maintains that mover and movable among them are not
really different (*distincta per se*) because "the
movable thing is in potentiality, and the mover in actuality"
(LC 161K; MC Wolfson
 673-674).[8]
 The four elements are composed each of prime matter and a simple
form, for instance, the elementary form of earth is coldness and
dryness. Averroes affirms that the form is their mover, and matter,
their movable thing (see below c. 12). Under this conception the
movable cannot oppose resistance to the mover, and motion without
medium would be impossible, because it would be in no time. The medium
makes motion possible because it introduces time (LC 161H; MC Wolfson
403-408). Averroes wanted to defend Aristotle and found this
explanation. Its weakness is obvious but the denial of motion in a
void prevailed in medieval science (Maier 1952: 221-223, 1958:
244-274).


## 10. Time



According to Aristotle, motion and time are not the same but time
cannot be isolated from motion, and. if we are not conscious of any
change, we are not aware of time. He tells of the men in the fable who
slept with the heroes in Sardinia; when they awoke, to them no time
seemed to have elapsed (*Phys.* IV.11, 218b21-25).
Averroes read the story in the Arabic translation but he adapted it to
the Islamic context, and those men became the "People of the
Cave" mentioned in the Qur'an 18:9-26 (LC 178B T97).
However, the SC keeps the Aristotelian example (SC 58:
10-11).



More significant is Averroes' interpretation of time as an
accident of motion (Trifogli 2001, 62). Since motions are many, he
wants to identify that motion the accident of which time is (LC 178G
T98). If we assume that time is the accident of the celestial motion,
those who do not perceive this motion, "like those of whom Plato
says that they have been incarcerated underground since their
childhood" (*Republic* 7, 514a-517a) will not
perceive time at all. And if time is an accident of any motion, there
will be as many times as kinds of motion. Averroes solves the dilemma
making a double interpretation of time. Our perception of time in so
far as we are beings undergoing change is the primary perception of
time, and



> 
> 
> it is evident that we only perceive that we are in a changing being
> (*transmutabili*, LC 179B) because of the change of the
> heavenly body.
> 
> 
> 



And he adds that if the heavenly body would be at rest, we would have
the nature of an unchanging being, *in esse non transmutabili*.
This perception follows time essentially, while our perception of time
in relation to any motion otherwise is only accidental. Averroes
admits to have arrived at this opinion after long enquiry, *post
magnum tempus*, since in earlier times he followed the
commentators (LC 179G).



Time is defined by Aristotle as the number of motion in respect of
before and after (*Phys.* IV.11, 219b1-2). Averroes
expounds that 'number' is like the logical genus and
'before and after' the specific difference (LC 181F
TC101). The definition was subject to discussion among Greek and Arab
commentators, and Averroes refers to Alexander of Aphrodisias and
Themistius, and to al-Farabi. For Averroes the
definition of time about which there is no doubt is that "time
is the numerable one of the before and after existing in motion"
(*numeratum prioris et posterioris*) (LC 181H TC101), that is,
before and after is a condition existing in motion, and its
numerability is time. Averroes has the same explanation in his Short
Commentary: "When Aristotle says that time is the number of the
preceding and the following he means that time is the numerable one
(*ma<dud*) of preceding and following that exists in
motion" (SC 61: 12).



Because time numbers and measures, it is similar to the numbers we use
in counting (*assimilatur*, LC 182B TC102). When Aristotle
later says that motion and time number and measure each other
(*Phys.* IV.12, 220b14-32), Averroes gives his view: time
numbers and measures motion essentially (*per se*) and it is
numbered and measured by motion accidentally "because the
substance of time is number of motion" (LC 188D TC112). By
employing the term *substantia* to time several times Averroes
shows that he sees time as a certain entity in itself.



Time measures also things that are at rest because they exist in time
(221b8-9). The Arabic translation does not insert
"incidentally" to restrict "measures"
(*Tabi`a* [1964: 456: 4-5]). In his
commentary (LC 192F TC118; MC Wolfson 647), Averroes shows first his
concern for things that are eternally in motion like the universe and
things that are eternally at rest like the earth: he says that they
cannot be measured by time (LC 192L). Therefore, time measures motion
and rest; it measures motion essentially and primarily, and it
measures rest incidentally and secondarily, i.e., "as it is
deprivation of motion" (LC 193L); the solution fits in with
Averroes' way of thinking.



Should we look at the processes of coming-to-be and passing-away we
meet with similar interpretation. The elements change one into
another; water exists for a while and then turns into air, for
instance. In particular, individual living beings have a limited life
span; thus a linear dimension extends to them while the whole
undergoes a continuous cycle of coming-to-be and passing-away, and its
dimension is circular. Time measures the limited duration of sublunary
beings, and the eternal motion of the spheres makes cycles eternal. To
link both dimensions, Averroes introduces the motion of the sun along
the ecliptic, the inclined circle that marks the sun's
 path.[9]



> 
> 
> For this circle, as Aristotle says, in addition to the continuity and
> perpetuity of the motion in it, has the added feature of possessing a
> duality of movements, one of approach and one of retreat. (Averroes
> [MC GC En]: 101)
> 
> 
> 


## 11. Continuum



In *Physics* V.3, 226b18, Aristotle begins to talk about the
notions of 'together', 'apart', 'in
touch', 'between', 'next in succession',
'contiguous' and 'continuous'.
*Physics* 226b23-27 is a sentence out of place and
Ishaq translation does not contain it. His translation goes
on:



> 
> 
> What moves continuously is that which has no gap at all, or a minimal,
> in that thing (*pragma*: *ma`na*) in which
> its motion happens, nor [a gap] in time. A gap [in time] does not
> prevent the [highest] musical note Zir (*neate*) from
> coming after the [lowest] musical note Bam (*hypate*) in
> place. I mean only the thing in which motion happens, and this is
> evident in movements that happen in place as well as in all others.
> (*Tabi`a* [1964: 540-541]; cf.
> *Phys.* V.3, 226b27-32)
> 
> 
> 



Bessarion almost skipped the musical example, but Scotus had
translated Ishaq's text together with Averroes'
commentary (LC 223 HI T23). Aristotle admits minimal breaks in his
definition of continuum, and his musical instance refers to the
possibility of omitting a few notes, and that nevertheless, the
transition to be continuous (Ross 1936: 628).



This definition of continuum looks contradictory in itself, but
Averroes remains faithful to Aristotle and widens the range of
possible breaks in a continuous change and motion. Many movements are
continuous although they have small breaks in the thing
(*ma`na*: *intentio*) like animals when they
walk, "but those that fly or swim do not have a break at
all" (LC 223L T23).



Averroes explicitly backs Alexander's account that Book VI
follows Book V because the beginning of the former makes use of the
"descriptions" of the continuous, contiguous and next in
succession objects that were set up in Book V (LC 246L T1). Aristotle
strives to prove that a continuum cannot be composed of indivisibles,
and he gives the example of the line, because a line cannot be
composed of points. The cause for the continuum in magnitude, spatial
extension (*megethos*) is pleaded with various arguments, and
it is shown that time and motion are continuous too (*Phys.*
VI.1, 231a21-233b32). They are always divisible.



The same seems to apply for the subject of change: "Anything
that changes must be divisible" (*Phys.* VI.4, 234b10),
but Averroes has read the commentators and knows their doubts (LC 265I
T32). First, does Aristotle mean only motion in the three categories,
quantity, quality, and place, or does he also mean change in
substance? Second, if there are changes in no time, how can the
movable be partially there where it starts and there where it
ends?



Alexander denied the existence of changes in no time, but "all
the Peripatetics admit changes that take place in no time, as this is
evident in lights and similar actions" (LC 265L). Themistius
believed that Aristotle did not intend here any change in no time.
Avempace claimed that the divisibility that Aristotle means here is
not the divisibility according to the last point, *secundum
ultima*, but according to the circumstance that in the movable
there are two contraries, during the interval, and Averroes adds
"I sustained this view long time ago" (LC 266C; cf. SC
99:13-100:2), and he had actually affirmed that Avempace had
solved the issue (MC Wolfson 544-545; MC Kalonymos L 81vo
& O 64vo).



Averroes admits changes in no time but he restricts them to accidental
changes, and they are those which are the aim of another change and he
gives the instance of lighting the room thanks to the motion of the
candle. Since they result from another change, they are divisible in
so far as the main movables are (LC 266F). As Cerami remarks, this is
how Averroes wants to solve the aporia of the instantaneous changes
(Cerami 2015: 406).



For the changes that Averroes calls "essential", Aristotle
stresses that during the process of change the movable must be partly
under one condition and partly under the other. He explains: when
white changes into black, it is partially white and partially grey, as
grey is the first degree of change (*Phys.* VI.4,
234b17-18).



Averroes verifies the fact in changes in quality--color,
temperature, place, and substance. In all we find a first changed
thing that is partially in that from which it changed and partially in
that into which has primarily changed (LC 266I). Let us quote his
words describing substantial change:



> 
> 
> However the first [thing] in coming-to-be and passing-away is the
> minimal part of the generated [substance] being able to exist;
> "minimum" there is a [minimal] complete quantity in any
> generated [substance], for instance, the minimal part of fire is
> complete, i.e., the minimal part that is capable to be fire,
> *minima pars*, *quae potest esse ignis*. (LC 267D
> TC32)
> 
> 
> 



Above we read that "animals that walk" have minimal breaks
in their local motion and now we face an even more serious challenge
to the continuum theory. It should be noted that Ruth Glasner has
argued that Averroes in this passage develops a new doctrine of
change, namely, change as "a contiguous chain of intermediate
changes" (Glasner 2009: 122-127). Moreover, she has shown
that Averroes' breakdown extends to the composition of the
bodies that are generated and perish, so that actual minimal units
exist, "units having mater, form, and specific natura
motion" (Glasner 2009, 159). Glasner has adduced evidence to
support Averroes' originality and the significance of his
innovative doctrine for the history of modern 
science.[10]



Averroes had to go back to the issue in his interpretation of Book
VIII.3, 253b6-31, where Aristotle denies the processes of
increase and decrease and of qualitative change to be always
 occurring[11].
 His commentary is unusually long (LC 358D-360F TC23) and
Averroes asks himself why Aristotle had to refute something apparently
obvious. He conjectures that the reason is because continuity is
hidden in quantitative and qualitative motions (*in motibus
augmentationis et alterationis*, LC 359H). He gives the
Aristotelian example of the stone being worn away by the drop of water
and then discusses how the process takes place. The stone loses each
time a certain part, and not whatever part but the first actually
created one (*prima pars facta in actu*, LC 359G), and the same
rule applies to the falling drops of water. They are complete parts.
Averroes recalls that Aristotle had said in Book VI (234b10-20)
that what changes does not have a first part, and he sees there a
difficulty but he explains:



> 
> 
> Let us say that the first part that is generated from the motion is in
> some way in actuality and in some way in potentiality because it is
> determinate as that which will be in actuality, and under this aspect
> it is not divisible, and it is divisible in so far as motion is
> continuous. (LC 359KL; LC Schmieja8 79: 9-12)
> 
> 
> 


## 12. Change in Substance



At the beginning of Book V of the *Physics*, Aristotle makes a
distinction between change (*metabole*) and motion
(*kinesis*). Aristotle classifies the changes *per
se* from two angles: the terms *whence* and
*whither* of any change and motion and from the angle of the
categories. From the first angle (*Phys.* V.1,
224b35-b5), change can take place through four ways:


1. from positive *A* (*hypokeimenon*, Arabic
*mawdu`*) to positive *B*,
2. from positive *A* to negative *A*,
3. from negative *A* to positive *A*,
4. from negative *A* to negative *B*.



(4) is not a change at all, because not-*A* and not-*B*
are neither contrary nor contradictory. (2) is passing-away and (3) is
coming-to-be, and these two changes are not motion. The only change
that is a motion is (1) from positive *A* to positive
*B*. Averroes interprets *A* (the Latin translation
reads *subjectum*) as 'being' (*esse*), and
*non subjectum* becomes 'non-being' (*non
esse*), but immediately he adds:



> 
> 
> I understand under not being not being in actuality, that is being in
> potentiality, and [that is] not being in general
> (*universaliter*), that which is characteristic of Prime
> Matter, and not absolute non-being. (LC 211E TC7; MC Wolfson
> 514-516)
> 
> 
> 



From the angle of the ten Aristotelian categories (225b5-b10),
there are three kinds of motion: qualitative (how), quantitative (how
much), and local (where). Averroes observes:



> 
> 
> The commentators ask here in what manner [Aristotle] places motion
> under three different genera, although he placed it as a genus in
> itself, namely under the category of being affected. (LC 214K TC9)
> 
> 
> 



Some of the commentators voiced the opinion that the category of
being-affected is a genus for motion under the consideration of
"receiving the motion", others, that quality, quantity and
place are partially moving, partially at rest, and others disagree,
and do not accept quality, quantity and place as genera for motion.
Averroes considers it wrong to enter motion into the category of
being-affected because motion is something the movable receives.
Averroes' view is summarized in his own words:



> 
> 
> Motion has a twofold consideration because according to its matter, it
> belongs to the genus of that toward which it moves, but according to
> its form, namely, according to its being change
> (*transmutatio*) linked with time, it belongs to the category
> of being-affected. (LC 215B
>  TC9)[12]
> 
> 
> 



Motion does not take place in substantial change, that is,
coming-to-be or passing-away because there is nothing contrary to
substance (*Phys.* 225b10-11). Averroes comments on
"contrary" and explains that the contraries here involved
have "intermediate" states (*mediata*), no matter
their form or condition (LC 215F TC10). Averroes refers to the
commentaries of Alexander on *De generatione et corruptione*
and Themistius (without identifying the work which the latter
comments) and their arguments. He develops his point of view:
Aristotle's doctrine that changes in substance are not motion
because substance has no contrary is well known (*famosa*) but
it seems to him more adequate to say: "coming-to-be and passing-away
are not motion because they are in something which is potentiality,
not in actuality, and motion is in actuality" (216A TC10; MC Wolfson
518). If there is motion in substantial change, it is only
accidentally (LC 216C), but motion plays its role in necessitating
it.


## 13. Substantial change as coming-to-be



Change in substance is the main subject of Aristotle's *De
generatione et corruptione* although the other two kinds are
examined too, namely, growth and alteration. Substantial change
implies absolute coming-to-be and perishing, and first matter is
assumed as their ground; it takes place in an absolute, unqualified
way (*haplos*) (GC 317a 32-34); absolute coming-to-be and
perishing divide again into simple (*haplous*) and composite
(*synthetos*) forms. The Arabic uses *`ala
al-itlaq* for 'absolutely,' and
*basit* for 'simple'.



Averroes wrote a Middle and a Short Commentary on Aristotle's
treatise and his approach is somewhat different in each one. The Short
Commentary or Epitome places the treatise in the context of
Aristotle's works. We are told that the book belongs after the
*De Caelo* and that "in an earlier work," i.e., the
*Physics* change in place was examined. Growth was 
examined in the books *On the Soul* and *On Animals*,
and coming-to-be was also studied in the *Meteorologica* (Averroes,
SC GC En, 113), but its treatment is now different: 



> 
> 
> With regard to simple generation, he explains it here completely , but
> with regard to the generation of composite [bodies], he does it, in
> this book, at the level of the genus of the topic *(amr*),
> giving account of its principles and elements
> (*ustuqusat*) (Averroes, SC GC Ar, 3: 11-4: 2
> Arabic).
> 
> 
> 



Averroes divides the genus of coming-to-be and perishing into two
kinds simple and composite. Simple generation is found in the
so-called elements (*ustuqusat*) and chapters 1-8 of
Book II of *De generatione* identify them as Earth, Air, Fire,
and Water and justify why they are only these four and how they change
into each other. The issue of the ether, the fifth element, is left
aside in this treatise. No need saying that his argumentation is based
on the preeminence of the sense of touch, something which is obviously
questionable, but the classification was successful for many
centuries.



For a modern reader, more important than the reality of the four
elements seems to be Aristotle's doctrine of the contrarieties
as well as the double dimension active and passive of their potencies
(in particular, c. 2, 329b 7 - 330a 29). Joachim considers that
the contrarieties (*enantioseis*) in Aristotle are merely
"couples of contrasted qualities" (Aristotle, GC Joachim
1926, 200-201) but Averroes was more specific and wrote
*al-mutaddadat al-ula /
al-uwwal*, the primary contrarieties (*contrarietates
primae*, *haphakhim re'shonim*) so that we should
look for the reasons of his precision.



Since Philoponos' commentary is extant, we may turn to it for
his interpretation of the passage (Philoponus GC Gr 1897, 213: 1-223: 27). For him Aristotle's doctrine of the contrarieties
considers them as principles, *arkhai*. There are three
principles according to Philoponus: matter is the first principle,
form "which is the contrariety" is the second, and the
third is the simple body. (Philoponus, 123) The translation by
Williams reads that :"the principles are three, first matter, second
the enmattered form which is the same as the contrarieties, and third
the simple bodies which he says come to be out of matter when it takes
on the contrarieties" (Philoponus 2013, 123).



Averroes knew the commentary and therefore, that they were principles
and that they were on the same level as first matter. One should not
dismiss the possible reading "primary contrarieties" in
the Arabic translation used by Averroes. The Aristotelian tradition
taught him that hotness/coldness and dryness/moistness are principles.
Furthermore, the capacity of acting was related to one of the members
of the couple of primary contrarieties, and that of being affected to
the second. Their dual combination was substantial form, and Averroes
stressed it: "The proximate matter of the simple bodies is the
prime matter, as has already been shown, and their forms are the
primary contrarieties existing in them" (Averroes, SC GC, 27:
6-8). The Middle Commentary expresses the very conclusion in similar
terms (MC GC En, 70)



As for the question whether the "primary contrarieties"
--as enmattered form-- are active or passive powers, Philoponus
commented on GC 329b 24 - 26 and observed that the elementary
qualities, or contrarieties, have a power to act and a capacity to be
affected, and that "in the case of their coming-to-be from one
another they are all alike capable both of acting and of being
affected" (Philoponus 2013, 128). Avempace was very sensitive to
the issue and extended in an excursus when writing his own commentary
and was clear in accepting an active and a passive power in each
element, for instance, in the element water (Avempace 1994,
65).Averroes, in the Epitome, summarized Aristotle's views that
only hotness/coldness and dryness/moistness can be the primary
contrarieties because they are powers, *quwa*, while
heaviness and lightness, in spite of their being tangible qualities,
are not. Averroes insisted:.



> 
> 
> As for heavy and light, however, although they are present in the
> simple bodies, they do not belong to them insofar as they are elements
> since they are neither active nor passive forces [powers], whereas the
> forms by reason of which the simple bodies are elements must
> necessarily be active and passive (Averroes, SC GC En, 124) (SC GC Ar,
> 30: 2-5). 
> 
> 
> 



When it comes to the Middle Commentary, and to the words of Aristotle
describing "hot and cold" and "dry and moist"
(GC 329b 24-26), Averroes reflects on the sense of the terms and
expresses his doubts about their right meaning. Their description does
not match the meaning that the term has in the colloquial language,
nor the various meanings collected by lexicologists, and maybe those
who theorize about them, understand them differently, he doubts.
Finally, Averroes writes that "hot and cold" and
"dry and moist" are



> 
> 
> Things whose existence in these qualities is evident in itself, i.e.,
> these actions described by them [are evident]; the descriptions are
> taken from their properties. However in that [the Greek] language they
> [the descriptions] happen to be generally accepted and intellectually
> apprehended which prove the names given to them. For us they are only
> intellectually apprehended (*ma`qul*), not generally
> accepted (*mashhur*) (Averroes, MC GC Ar, 92: 
>  5-8).[13]
> 
> 
> 
> 



Therefore, Averroes will use "hot and cold" and "dry
and moist" only as intellectually apprehended concepts, namely,
primary contrarieties and consider them "the specific
differences (*fusul*) of the elements"
(Averroes, MC GC Ar 2005, 92: 9). Averroes does not deny the primary
contrarieties to be powers, but in the Middle Commentary, he
underlines the genus/species classification. The Short Commentary
follows the line of the primary contrarieties and produces following
syllogism:



> 
> 
> [Minor premise] These four bodies are those bodies in which the
> primary contrarieties exist and their number is equal to the number of
> the possible compositions of the primary contrarieties.
> 
> 
> 



> 
> 
> [Major premise] The bodies in which are existing those primary
> contrarieties and whose number is equal to the number of the
> contrarieties are the elements.
> 
> 
> 



> 
> 
> [Conclusion] Therefore, the elements are those bodies and their number
> is equal to the number of those bodies (Averroes, SC GC Ar, 35) (SC GC
> En, 127).
> 
> 
> 



The Middle Commentary does not make recourse to the syllogism but both
commentaries agree on the conclusion "that all bodies are
composed out of all of the four bodies which are called
elements" (Averroes, MC GC En, 96). Quantities of fire, air,
water, and earth - even minimal parts-- are the ultimate
components of tissues and limbs, or organs.



Since Averroes was very aware that any philosophical enquiry is about
causes, this was also the case in the investigation concerning the
generated and corruptible beings. The elements are composed of matter
and form but they cannot be generated out of one another, nor can they
combine with each other and generate composite bodies unless the third
principle intervenes, and this principle is the efficient cause
(*fa`il*) . The efficient cause is present in all
changes, and requires a previous local motion. There is a local motion
which is inherent, natural to each kind of element, and another which
is external. The latter brings two elements in contact, one acts and
the other reacts, so that a mixture is produced. The mixture is the
last condition for the coming-to-be or perishing of the elements.
Aristotle and his disciple, Averroes, were convinced that the
explanation should be true.


## 14. Alteration, Growth, Nutrition



The Middle Commentary on *De generatione et corruptione* is
systematic in organizing Aristotle's original. As in the case of
the Middle Commentary on the *Physics*, Averroes draws a
synopsis, where he divides the content into the 2 books,
*maqala*, each one into sections, *jumla*, and some
of the *jumla* into chapters, *fasl*, following
the method of the *divisio textus*. Averroes paraphrases GC
314a 1-4 in I.1 and writes that Aristotle's purpose was
"to explain the causes that are common to all naturally
(*bi-l*-*tab`*) generable and corruptible
things to explain as well the causes of growth and alteration",
(Averroes, MC GC Ar, 2: 3-4) (MC GC En, 
 4).[14]
Natural here opposes artificial.



Therefore, Averroes and Aristotle agree in separating change in place
from the three other kinds, and they want to look into the common
causes of the three. Coming-to-be has been analyzed above, alteration
and growth remain to be. Alteration (*istihalah*) is
change in quality, in which the underlying subject, or substratum
(*mawdu`*) remains one and the same throughout
the process. The *mawdu`* is "a definite
thing existing in actuality" and there are plenty of examples
(Averroes, MC GC En, 24) (MC GC Ar , 30: 6). There is not much
discussion about alteration.



Growth and its opposite, diminution, come to the fore and are easy to
understand, because they affect the animated beings
(*emphsykha*) and these changes are at the very essence of life
and death. Aristotle treated the subject in other places, *De
anima*, *Generation of the Animals, Parts of the Animals*,
but in GC I.5, 320a 5 - 322a 33, he discussed growth in contrast
to coming-to-be and alteration. The passage was commented by
Alexander, whose text was known to Averroes but not to us; we have to
rely on Philoponus who also discusses the issue of growth at length in
his own commentary on GC (Philoponus GC Gr 1897, 69: 27-123: 26), as
an indirect source.



Any explanation has to look for the material, formal and efficient
cause of the investigated object. Aristotle observed that
"Matter in the chief and strictest sense of the word is the
substratum which admits of coming-to-be and passing-away; but the
substratum of the other kinds of change is also in a sense
matter" (GC 320a 2-4) (GC Forster 1955, 203), but as for
"in which sense" he left the question open. Maybe this was
the reason why Averroes introduced the notion of corporeality in
answering it:



> 
> The corporeality (*jismiya*) which is common to all that
> is generated in substance, is one in number in potentiality, not in
> actuality, while the corporeality which is the substratum for
> alteration is one in number in actuality (Averroes, MC GC Ar, 32: 2-4)
> (MC GC En, 26).
> 



The editor, Eichner, as well as the translator, Kurland, draw the
attention of the reader to the fact that the whole paragraph
(Averroes, MC GC Ar 2005, 32: 1-12) is missing in the Hebrew and Latin
translations, and in the Arabic manuscript (Oxford Bodleian 34) and
that it appears in the body of one Arabic manuscript (Paris 1009) and
in the margin of another (Modena 13), so that one doubts whether
Averroes is the real author but, in any case, the explanation is
half-finished.



Philoponus had said "The matter of corporeal substance is one
thing, that of growth another (Philoponus GC En 2013, 116)", but
he saw that the distinction was purely "in definition"
(*toi logoi*) following Aristotle GC 320b 24.
Averroes knew it and sets forth that growth takes place "out of
a body existent in act" (MC GC Ar 2005, 38: 6). He then
considers the difficulties already raised by Aristotle because of this
statement. The solution to the problem is obtained by means of
examining how growth occurs. Aristotle discerns three characteristics:




(a) Every part of the growing magnitude is larger--for instance,
if flesh grows, every part of flesh grows; (b) it grows by the
accession of something; and (c) that it grows because that which grows
is preserved (*sozomenon*) and remains (Aristotle, GC
Forster 1955, 213).



In Averroes' paraphrase of the passage, (a) reads more specific
"every drop and every perceptible part grows in the same manner,
and likewise, when it diminishes, it does in every perceptible
part". Characteristic (c) reads also differently: "the
thing which is characterized by growth and diminution must be definite
(*mushar ilayhi*) and remain identical" (Averroes, MC GC Ar
2005, 39). Averroes makes clear that growth is not an increase in
volume, and that the homoeomerous bodies play the key role.



The Aristotelian tradition consider the organic tissues, like blood,
flesh, or bones, but also, minerals, like gold or silver, homoeomerous
bodies. They are composed of the four elements and the composition is
in accordance with a blend specific to each body. The living being
grows when their tissues, i.e., their homoeomerous bodies, increase
their size. Certainly, the existence of principles or causes is known
in the case of growth as it was made clear in the case of the four
elements: they were the material, formal and efficient cause. 



Averroes understands that growth occurs primarily (*awwalan*)
in the homoeomerous bodies, which are matter for the organic
(*aliyah*) bodies, while these organs, or limbs, grow
through growth occurring in the homoeomerous tissues (Averroes, MC GC
En, 33) (MC GC Ar, 41: 9-10). And so, Aristotle saw that the
homoeomerous bodies interact as material and formal causes, "for
the form as well as the matter is called flesh or bone" (GC 321b
20-22).



Matter is fluid (*sa'il*) and form, persistent
(*thabit*) and so, form is determinant; the form of flesh
or bone determines the homoeomerous body. As the magnitude is not
unchanging, growth needs food to be brought in from the outside, and
food must give up its specific form and become flesh or bone
"through a process of mixture" (Averroes, MC GC En,
39).



Averroes faces an objection by Alexander of Aphrodisias concerning the
assimilation of the food; the passage has been thoroughly studied by
Eichner (Averroes, MC GC Ar 2005) who translated all the relevant
texts. Alexander was awfully admired by Averroes but was criticized by
the latter in his Middle Commentary. Alexander--according to
Averroes--sustained that there is a moisture, or humidity
dispersed (*mabthutha*) throughout all of the limbs, that
the incoming food mixes with it and that as a result, food is
transformed into the "nature of this
moisture" (*tabi`a tilka
l-rutuba*) (MC GC Ar 2005, 44: 2). Its increase is
growth and its decrease, diminution, but the shape of the limbs is
stable. If this account--such as it is given in the Middle
Commentary--were Alexander's, then Averroes' critique
would be permissible from his point of view, because the doctrine
would be valid only for things undergoing mixture (MC GC Ar, 48: 16).
It seems more adequate to regard Alexander's physiological
explanation as insufficient.



Physiology set apart from the discussion, philosophy is that which
must give a comprehensive explanation using the instruments available
to the philosopher, i.e., the distinction between matter and form,
between being itself, *per se* and *qua*,  *min
jihatin ma*, and between quality and quantity. Form *per
se* does not grow but insofar as it is quantity endowed with form,
it does (MC GC Ar, 45: 2). Matter *qua* matter, i.e., *per
se* cannot grow but in so far as any perceptible part possesses
matter, it is needed and present. Averroes concludes:



> 
> The Master indeed did not mean to say that growth takes place in the
> form to the exclusion of the matter, nor in the matter to the
> exclusion of the form, but he did mean to say that growth takes place
> in all parts of the growing thing due to their form, not due to their
> matter by virtue of which they are parts (Averroes, MC GC Ar 2005, 46
> 18 - 47 2) (MC GC En 1958, 37).
> 



Since the participation of the material and formal principle has been
clarified, we should proceed with analyzing the efficient cause with
respect to growth, that Aristotle considered in GC 320b 17-22 and
again in GC 322a 28-33. Let us not forget that Aristotle placed the
principle of motion, (*arkhe tes kineseos*,
*mabda' al-tahrik* ) i.e., the efficient cause
of alteration and of growth in the thing which undergoes alteration or
growth (321b 6-10). 



Growth and nutrition are intrinsically linked to life, and require the
vegetative soul investigated by Aristotle in *De anima* II 4
(416b 18-31). The vegetative soul is also generative
(*psykhe genetike*), producing the power to grow
(*dynamis auxetike)*. Joachim identified the form of
the growing thing with this power in his commentary on GC 322a 28-33
(GC Joachim 1926, 135-136) and so did Averroes. He says that the
growing thing has a power due to which it has a form. It is
"endowed with form" (*dhu sura*),
so that "Were it not for the presence of that force in the
growing thing, growth in all the sensible parts of the growing thing
would be impossible" (Averroes, MC GC En 1958, 38) (Averroes, MC
GC Ar 2005, 48 13-15) .



On the other side, Aristotle mentioned the efficient cause of
coming-to-be in 320b 17-22, although in a generic way. Philoponus
interpretated it as something applicable to growth too (Philoponus
2013, 114-115) and introduced the strict term, *poietikon
aition* (Philoponus **CAG** 1897, 83: 25-26).
Averroes follows him and compares coming-to-be and growth with respect
to the efficient cause (*sabab fa'il*) (MC GC Ar,
37: 9-15) arriving at the conclusion that the efficient cause is not
only in the growing thing but also of the same species as its parts.
Averroes has set forth the material, formal and efficient causes in
the processes of growth, and diminution, as close as possible to
Aristotle, which was his purpose. The preeminence of form has shown in
many aspects, that of principle of life being indisputable.


## 15. Movable and Mover



Book VII begins with the statement "Whatever is moving must be
moved by something" (*Phys.* 241b24), and Averroes
comments on it: "In this treatise [Aristotle] searched whether
every movable has a mover", and he points out that Aristotle has
in mind those movables in which the mover is not clearly distinguished
from the movable, "as in the four elements" (*ut
in*, LC Schmieja7 1:20-2:1; *absque*, "except
for", LC 306B
 T1).[15]



Later, in Book VIII, Averroes considers that Book VII did not deal
with motion because of 'leaning' in particular, and that
Book VIII finishes the task. In this book he classifies essential
motions in two kinds: violent and natural, and he divides the latter
in 'motion because of the soul' and 'motion because
of leaning' (*declinatio*: Arabic *mail*), which
includes gravity and levity, that is, the motion of the elements to
their natural place (LC 366D TC28). Since natural motion of the four
elements seems to happen by itself, Aristotle put forward several
arguments to prove that they are not moved by themselves
(*Phys.* VIII, 255a1-b30) but the chapter ends
acknowledging that "[the element] possesses a principle of
motion in itself, although not of setting in motion nor of acting but
of being affected".



Averroes examines the sentence and interprets it in a sense that he
considers to be Aristotelian. The simple element has two movers, an
essential and an accidental one (LC 370B TC32). What moves essentially
is



> 
> 
> that which is external, that is, the generating [cause;
> *generans* : *mukawwin*] and the generating
> [cause] is that which gives its form and all the accidents resultant
> from the form--one of which is the local motion--to the
> generated simple body. (LC 370G
>  TC32)[16]
> 
> 
> 



Generating acts upon matter and in this manner, Averroes places the
principle of motion in it, because matter is "that in which the
true potentiality for motion is, that is, the potentiality for
receiving motion" (LC 370H). The issue was of import in Arabic
and Jewish natural philosophy (MC Wolfson 669-675), while the
Latin thinkers were most interested in the question how the four
elements remain in the mixture, a question that Averroes also wanted
to answer (Maier 1952: 28-31).



Averroes discusses two points related to the mentioned issue of how
the four elements are moved. First, Galen maintained that the
arguments brought to support the thesis "Whatever is moving must
be moved by something" are false. Second, other commentators
considered Book VII redundant, because VIII deals with the same
subject in a more comprehensive way (LC 306C; LC Schmieja7
2:1-4), and actually, Book VII pleads that there is a first
mover which is not moved by anything else. Averroes' discussion
goes as follows:



1) To prove that "Whatever is moving must be moved by
something", Aristotle chose a body "A\_B which is moving
*per se*, and not by virtue of some part"
(241b37-38). Averroes carefully distinguishes movable
essentially, *per se* or accidentally, *per accidens*
and movable as a whole or by virtue of some part (LC 306F; LC
Schmieja7 2:19-3:1). He gives us an instance of that which moves
by itself but not as a whole:



> 
> 
> Thus the first essentially movable (*primum motum*) in animals
> is the heart which does not move as a whole, because one part of it
> moves itself, and moves the whole. (LC 306F; LC Schmieja7
> 3:1-3)
> 
> 
> 



The whole does not move itself, only one part moves essentially, but
the whole here is a composite the parts of which are continuous.



Aristotle argued that if a body moves as a whole, primarily and
essentially, it need not stop moving because something else has
stopped moving. And if something is at rest because something else has
stopped moving, that thing must be moved by something (*Phys.*
VII.1, 241b44 [Ross 1936: 419).



For Averroes, Galen and others misinterpreted Aristotle. They
identified that which is only contrary to that which moves
accidentally with that which moves essentially (LC 307H; LC Schmieja7
6:3-6). Indeed that which moves essentially (and as a whole) is
opposed to that which is moved by virtue of one part of it. In
Galen's view, if one part of a movable would come to rest, the
whole should not. In the case of the heart of the animals, Galen
contested the doctrine that it is the first movable because when the
heart is removed, the animal is still capable of walking two steps.
Galen claimed that the head is the source of motion, but Averroes
objects "I saw a ram walking after the head was cut off"
(LC 309C TC4; LC Schmieja7 11:21-22). But there are primary
movables that fulfill these conditions and it is worth quoting
Averroes' words:



> 
> 
> There must be here first movables because natural bodies do not divide
> infinitely into that for which they are natural bodies, e.g., because
> the first movable in fire is the minimal part that is capable of being
> fire in actuality. (LC 307I TC2; LC Schmieja7, 6:10-13)
> 
> 
> 



Aristotle's arguments were not very satisfying and the question
which are the bodies moving *per se* and as a whole was not
answered. Galen considered that the arguments were flawed, but
Averroes would never accept that Aristotle was wrong and made an
interpretation, that we cannot guess whatever the Master would agree
upon.



Ruth Glasner has shown evidence that Averroes borrowed the notion of
minimal parts from Alexander; she stresses the import of the new
doctrine that "bridges the gap between the two opposing systems,
the Aristotelian and the atomistic" (Glasner 2009:
146-159). Whether the smallest part actually exists or it is the
limit of divisibility is something that Averroes does not answer. The
context, however, hints at the second direction.



Therefore, Averroes sees the Book VII essential in order to prove that
"Whatever is moving must be moved by something" and the
Latin medieval philosophers will make of the statement *Omne quod
movetur necesse est ab aliquo moveri* a basic principle of
medieval physics.



2) At the beginning, Averroes complained that some commentators
considered Book VII superfluous, and in LC 312C TC9 (LC Schmieja7
20:15-18), he refers to Themistius as the main one. The final
arguments of *Phys.* VII.1 establish the impossibility of an
endless succession of movables and movers and, by *reductio ad
absurdum*, the necessity of a first mover. Consider the
following version of Ishaq's passage 243a3-4
(*textus alter*): "The first mover is not such because it is
that for the sake of which [motion happens] but because it is that
from which the source of motion is" (LC 311H;
*Tabi`a* [1964: 746: 3-6]). However M.
Scot translates the passage differently: "The first movable is not
such because it is that for the sake of which [motion happens] but
because it is that from which the source of motion is" (LC 311K; LC
Schmieja7 18:18-20). Averroes's copy of the
*Physics* was wrong and he hesitates: "Maybe there is an
error by the copyist, who should have placed the term
'mover' instead of this term 'movable'"
(LC 312 AB; LC Schmieja7 20:3-4 [more precise to my view]).



In spite of the hesitation caused by the wrong term, Averroes
interpreted that Aristotle distinguished here between a mover setting
in motion as a final cause or as an efficient cause (*quasi
agens*), and that Book VIII would clarify the matter concerning
the first mover. He was even more certain in asserting that Book VIII
would inquire about first motion, whether it is eternal or generated,
and he rejected Themistius' view that Book VII was superfluous
for this reason.


## 16. *Quwa* as Force



*Physics* VII.5 (249b27-250b10) discusses some problems
of simple mechanics (Lettinck 1994: 559-561). The moving-agent
is always moving something in a certain time and a certain distance,
and Aristotle presumes here that motion here is at a constant
velocity. There is a relationship between the four factors, for
instance if *A* sets *B* in motion over a distance
*C* in time *D*, *A* will move half *B*
over the distance *C* in half the time *D*, because
there is a proportion between the force of *A* and the load of
*B*. Aristotle sees limits to the interchange because "it
may well happen that it [a fraction of *A*] cannot move
*B* at all" (250a15-16). Thirty men can tow a ship
over a distance and in a time, but one man cannot tow it either over
any distance or in any time. He also faces Zeno's contention
that every grain of millet must make a sound when it falls as the
whole measure does stirring the air and answers that the grain is part
of a whole and that the whole is the moving-agent.



The wording was not clear and the commentators made their contribution
to explain it. Averroes, in his turn, insisted that Zeno's
discourse is fallacious because "one part does not set in motion
in actuality, but it does in potentiality within the whole" (LC
336F TC37; LC Schmieja7 79:7-8). Moreover, he set two
conditions, the movable has to be "prepared"
(*praeparatum*) and the power of the mover has to be
"complete" (*terminatum*).



> 
> 
> One man out of the thirty does not set the ship in motion on his own,
> [but] when his moving action (*motio*) joins the preparation
> and the
>  power[17]
>  coming from the 29 men, [he] will necessarily set in motion the whole
> ship; therefore each of the 29 gives to the ship a preparation to move
> (*moveri*) that it did not have before. (LC 336G; LC Schmieja7
> 79:8-12)
> 
> 
> 



Averroes sees the same process in the falling grain of
 millet.[18]
 Each grain cannot move the air on its own and make a sound. But each
grain gives the necessary preparation to the air. When the last added
grain passes the threshold and power is complete, the air is stirred
and a sound is made. This last part is not stronger than the others,
but it definitely causes motion "because of the preparation made
in the movable" (LC 336H; LC Schmieja7 79:8). Although he does
not explain what "preparation" is, we can gather that it
is a kind of potential energy. And as for the notion of
"complete power", Averroes seems to intend kinetic
energy.


## 17. First Movable, First Mover, Eternal Motion



1) Aristotle begins his Book VIII of the *Physics* raising the
question whether motion has come into being and will cease to be, or
is eternal "belonging to all beings as their immortal and never
failing property" (250b13-14). In order to answer it, he
develops various arguments the main one being based on the definition
of motion as the actualization of the movable in so far as movable
(251a10). If there was a first motion, and since any movable requires
a mover, there must have pre-existed a mover and a movable, something
capable of setting fire and something capable of burning, for
instance. If these have come into being, there must have been a change
before the supposed first change that brought them into existence. If
they pre-existed without change occurring, a previous change must have
occurred that set them into the condition of moving and being moved.
By *reductio ad absurdum*, it is proved that motion has always
existed.



Aristotle ends up by identifying eternal motion with a specific motion
that of the heavenly sphere, but in doing this he jumps from a
philosophical to a scientific explanation, and the leap is scarcely
justifiable. He can only assume that a single eternal motion exists
(Ross 1936: 91). Glasner describes it as Aristotle's failure to
overcome the so called succession argument (Glasner 2009: 76).



The Greek commentators concentrated on whether potentiality has to
precede motion or is simultaneous with it, and Philoponus adduced
heavy arguments against potentiality preceding motion (Puig Montada
1999). Averroes followed the tradition of those commentators for a
long time, he knew well the contributions by al-Farabi
and Avempace to the discussion and he sided with them. The beginning
of the Long Commentary hints at it:



> 
> 
> Since [Aristotle's] purpose is to inquire about the first mover,
> he begins by inquiring about motion, whether it is eternal or
> innovated, that is, according to the genus, and that which precedes
> this treatise, either is necessary to this section, or is for the sake
> of better. And when he said "Whether motion", he did not
> mean any specific (*proprium*) motion, but he wanted to know
> whether those motions existent in the parts of the universe came to
> be, after no part of the universe moved at all, etc. (LC 338FG TC1;
> Schmieja8, 2: 2-7 MC Glasner 94-95)
> 
> 
> 



In the same chapter, however, Averroes gives up this interpretation
that he considered to be what he calls "at first glance"
(*in primo aspectu*, LC 339A). After long investigation he
gained the deeper and true meaning of Aristotle's words: The
inquiry about motion concerns that motion embracing the universe, or
maybe several motions (if it is proven that the heavenly spheres have
several movers), that is, it concerns one species of motion, and wants
to know if it is eternal or innovated (LC 339C).



Of course, Averroes was wrong with his new interpretation of Aristotle
but the new interpretation helped him to design his vision of the
universe, and to counter the attacks of the Ash`arite theologians
against the eternity of creation. If a particular motion precedes
another one, the resulting succession, or
 continuity,[19]
 is purely accidental for Averroes and it is no basis for the
argumentation conducted by al-Farabi, Avempace, etc. On
the contrary the eternal motion of the heavenly spheres possesses
continuity *per se*, while the rest of motions possess
accidentally.



An objection could be raised against the new interpretation, and
indeed it had been raised by al-Ghazali (d. 1111 CE) in his
polemical writing *The Incoherence of the Philosophers*
(Ghazali [2002]). Potentiality has to precede motion, as
potentiality precedes the act; Averroes agrees with the tenet but
restricts it to the sublunary world, to innovated motions. The rule of
temporal priority does not apply to "motion as motion, but to
something innovated as innovated" (*novo facto*, LC
341IK).



2) Aristotle argues for eternity also from the angle of time,
endorsing the common belief that "there is always time"
and in *Physics* VIII.1 he concludes that it has been
demonstrated that there never was nor will be a time when motion was
not or will not be (252b5-6). Aristotle rejects the views of
Anaxagoras and Empedocles (252a5-b5). For Anaxagoras there is a
single principle of motion, Mind; for Empedocles Love and Strife
alternately prevail and cause motion. Averroes points out two
inconsistencies of their views. First, the laws of Nature do not
admit, "something to be possible for an endless time in the
past, and then to be brought into existence" (LC 349H TC15) and
second, its laws rebut that the mover and the movable are at rest for
an endless time and that then, at a given moment, motion starts.



Averroes compares Anaxagoras and Empedocles with the Ash`arite
theologians, who introduce the Divine will instead of Nature as the
moving agent, "they establish a voluntary mover" (LC
349I). The discussion goes at length (LC 349I-350L) and
parallels that of the First Question in the *Incoherence of the
Incoherence*. Averroes denies that an eternal will can originate a
temporally initiated action (*actio nova*). If the will is
eternal, the willed object has to be eternal, and *vice
versa*.



> 
> 
> The will does not postpone what it intends except because some cause
> (*intentio*) exists in the willed thing that did not exist at
> the time of [the action of] willing and if [that cause] was not there,
> that which is willed must be together with the will. If we would
> assume that there is a will in which the delay of the willed is
> possible, this would occur because something exists that did not exist
> before, i.e., because some cause, or disposition, was absent. There
> would be neither time nor anything because we affirmed that this will
> is the first motion, and it is obvious that this willed object must be
> together with the will. Therefore if we would affirm that the will is
> eternal, the willed would be eternal. (LC 349LM; Schmieja8, 43: 21-44: 6)
> 
> 
> 



The world of coming-to-be and passing-away shows however that there is
rest and that motions start and end. We see innovated events. Averroes
makes an exception to explain the apparent contradiction: The will can
precede the willed object through an infinite time although in an
accidental way and this is "clear to those who know the
difference between essentially and accidentally" (LC 350C). An
intermediate motion is the key solution and the motion he considered
was that which Aristotle searched for in Book VIII, i.e., the specific
motion of the heavenly spheres.



The theologians argued that an endless chain of motions was impossible
and that a first motion had to be created anew (*ex novo*).
Aristotle argued that motion is generically eternal since no beginning
can be determined. The former had a linear image of eternity and the
latter, a circular one. Averroes stepped in with an original proposal:
the succession of motions is accidental, not *per se*. But any
accident presupposes a propriety to which is related. The heavenly
motion is eternal *per se* and it is the reference to the
accidental eternity. Averroes answers the Ash`arites:



> 
> 
> We say that it [succession of motions] is essentially impossible, not
> accidentally, that is, if there was an agent whose being has no
> beginning, it resulted that his actions have no beginning. (LC 350D;
> Schmieja8, 40: 14-17; MC Glasner 82; MC Wolfson 495)
> 
> 
> 



and this kind of eternity is essential.


## 18. The Incorporeal First Mover



Aristotle reduced all kinds of change to local motion, and then to
circular motion, up to the eternal motion of the universe the mover of
which could not be movable at all.



Chapter 10 of Book VIII (266a10-267b26) accomplishes the
identification of this unmovable mover: It has no parts nor magnitude
(*megethos*), it is not material, it exerts an infinite force.
We face Aristotle's statement that "nothing finite can
produce motion for an infinite time" (266a12-13) and
Ishaq translated it faithfully: "nothing finite can
move anything for an infinite time" (Aristotle,
*Tabi`a* [1964: 924]). Nevertheless M. Scot
made a translation where he clarified the term "finite":
"a finite mover cannot produce motion for an infinite
time" (LC 423C). The principle is followed by two statements: no
finite magnitude can have infinite force, and no infinite magnitude
can have finite force (Ross 1936: 721). The statements fostered an
intense discussion in Averroes' Long Commentary. Averroes,
following Aristotle (266a15-23), shows the inconsistencies of
supposing a finite mover causing motion for an infinite time (LC 426BG
TC79). As for the second statement (266a26-b6), Averroes again
follows Aristotle and says that a body or a corporeal power does not
have an infinite action, therefore the mover with an infinite power is
not a body (LC 426G).



However, doubts can arise whether the proposition that all body has
only finite power applies to the celestial body or not (LC 426H). If
it applies, the celestial body has a finite power, and it is
destructible. If it does not, the resulting motion will be
instantaneous. The issue is very difficult and very exhaustive
(*multum scrupulosa*, LC 426K). Averroes knows the opinions of
Alexander of Aphrodisias, Johannes Philoponus and Avicenna. Alexander
affirmed that the celestial body acquires eternity from its mover;
Philoponus denied it and sustained that it is corruptible because its
potentiality, power, is finite. Avicenna would follow Alexander and
claim that the heavens are necessary because of another but its movers
are necessary because of themselves, and we understand: they are
eternal (LC 426LM). Then Averroes expresses his view on the celestial
body and its potentiality:



> 
> 
> But we say that from the meaning (*ex vi*) of Aristotle's
> words in this demonstration it appears that its passive--that is,
> accepting motion--potentiality is
>  infinite[20];
>  like an infinite action is not infinite because of a form in a body,
> an infinite affection is also not because of a form in a
> body--that is, a composite of matter and form. (LC 426M;
> Schmieja8, 301: 22-302: 4)
> 
> 
> 



Form always has a finite potentiality because it is divisible, and it
is divisible because the body of which it is the form, is divisible,
and the body is divisible because it is finite yet. The celestial body
is finite but its motion is eternal. Averroes finds a way-out of the
conflict: the celestial body is not composed of matter and form, it is
simple, and no material form exists in it (LC 427BC; MC Wolfson 594)
while form in material substances subsists because it is part of the
composite. By exclusion we can conclude: the celestial body is an
immaterial form.



Averroes recalls that in *De caelo* (in particular I.5-7)
Aristotle had stated that the potentiality of the heavenly body was
finite. An active, moving potentiality can be said to be infinite in
two aspects: because its activity never ceases or because it produces
motion at an infinite velocity, so that there cannot be any higher
velocity. The heavenly spheres rotate at different velocities,
therefore their motions are finite in the second aspect, i.e., in
intensity, and they are not caused by an infinite potentiality.
Averroes infers that Aristotle intended this meaning of
'finite' when he spoke of finite potentiality in the
heavens (LC 427BD; Davidson 1987: 321-331).



No doubt, Aristotle did not make it easy for Averroes who complains
how long he took great pains to find the explanation (*cum grande
labore et in tempore vitae meae non modico* LC 427D;
Schmieja8, 303: 13-14). But once proven that the first mover is not a
body, it becomes easier: the First Mover does not need to be affected
by the mentioned restrictions of corporeal movers, and it can produce
motion for an infinite time. And the First Mover becomes a
metaphysical principle like Prime Matter.


## Final Remarks



The natural philosophy of Averroes goes far beyond paraphrasing
Aristotle's texts; it echoes the discussions of the Greek
commentators, and the Arab philosophers on key issues. Furthermore,
Averroes faced in his lifetime the challenge of Islamic jurists and
Ash`arite theologians. First of all, Averroes had to legitimate
the study of philosophy and the consistency of its doctrines. His
prologue should be understood not only as an outline of his doctrine
of natural science but also as a defense of philosophy: Philosophy
grants man his intellectual perfection, and true happiness.



Averroes' views often respond to a dialectical treatment of the
subject. Aristotle's natural philosophy deals with Prime or
first Matter as one of its two main subjects, the First Mover being
the other. The existence of Prime Matter is in the root of a conflict
with the Ash`arite theologians who affirm changes out of a
non-existent subject, and Averroes can rely on Aristotle to rebuke
them.



Avicenna did not see himself in Aristotle's debt and his science
of the *Divine Matters*, what may be translated as metaphysics,
contained an original doctrine of being. Avicenna allocated a role to
the metaphysician in proving the existence of Nature or the
composition of matter and form in bodies and Averroes did not admit
such a role. Averroes' tense relationship with Avicenna shows up
also in their disagreement upon the existence of corporeal form, or on
the extent of necessity in Nature.



The definition of motion or change is no doubt one of the key issues
discussed by Averroes. Averroes decides on motion as an incomplete
state of each of the categories of substance, quality, quantity and
place, not as a category in itself and he paves the way for a medieval
theory of motion.



Averroes followed Aristotle in the rejection of atomism and the
defense of the continuum in motion, place and time. However,
continuity cannot explain all aspects of change and Averroes
formulates an original doctrine of minimal breaks. Moreover, the so
called "perceptible parts" are essential to growth, and
even to coming-to-be. C. Cerami pointed out that growth, for Averroes,
requires "minimal parts endowed with a finite quantity"
(Cerami 2012, 160) and then she discussed the issue of their
ontological status. Averroes did not go into the insoluble problem of
continuity versus atomism, but he focused on the efficient cause of
growth and nutrition: There is a power in the growing thing because of
its form.



The main conflict with the Islamic theological tradition concerns the
eternity of creation. Averroes interpreted Aristotle's argument
of *Physics* VIII.1 in such a way that the continuity of the
first motion was intended instead of motion in generic terms. This
allowed him to disable the argument for a limit in the succession of
motions and to maintain that the chain of motions is only an
accidental manifestation of the eternal motion of the heavenly body.
Furthermore, proving the incorporeality of the First Mover is the
final contribution to the theological view of the universe, from which
natural philosophy cannot be isolated.


## Abbreviations


### Physics



**Long commentary:** Latin translation by Michael
Scott


* [LC] *Aristotelis opera cum Averrois commentariis*: Quartum
volumen, Venice: Apud Junctas, 1562-1574, R Frankfurt am Main:
Minerva, 1962, ff. 1-433vo. Citations consist first of an
number and a letter, for instance 36A. The number indicates the folio
and the letter, its division, from A to M; the second part of the
citation, for instance TC60, refers to the commented paragraph.
* [LC Schmieja7] *Commentarium Magnum in Aristotelis Physicorum
Librum Septimum (Vindobonensis, lat. 2334)*, (Averrois Opera,
Series B), edited by Horst Schmieja, Paderborn: Schoningh,
2007.
* [LC Schmieja8] *Commentarium Magnum in Aristotelis Physicorum
Librum Octavum.* In der lateinischen Ubersetzung des Michael
Scotus, mit einer Einleitung herausgegeben von Horst Schmieja,
Frankfurt am Main: Institute for the History of Arabic-Islamic
Science, 2020.



**Middle Commentary:** In Arabic only the summary



Hebrew, 2 translators, only in manuscript form: Zerahya ben
Yishaq ben She'altiel, (Rome 1284) and Kalonymos ben
Kalonymos, (Arles 1317). Kalonymos's version is used with the
abbreviations:


* [MC Kalonymos L] Be ur emsa i  al Sefer
ha-shema  ha-tev i shel Aristo. The
intermediate commentary on the Physics of Aristotle (by Averroees, and
1 other text). British Library, Add MS 25879, copied 5241/1481.
* [MC Kalonymos O] Be ur ha-shema  le-Aben Roshd,
Oxford, Bodleian Library, Neubauer 1380, ff. 1-99ro
(Huntington 79; Uri 393), copied 5177/1417.



Latin, 3 translations, but all from Hebrew:


* [MC] Jacob Mantino, only the first three books: *Aristotelis
opera cum Averrois commentariis*: Quartum volumen, Venice: Apud
Junctas, 1562-1574, R Frankfurt am Main: Minerva, 1962, ff.
434ro-464ro.
* [MC Balmes] Abraham de Balmes. Vatican City, Bibliotheca
Apostolica, Vat. Lat. 4548.
* [MC Dactylomelos] Vitalis Dactylomelos, Paris, Bibliotheque
Nationale de France, lat. 6507.



English translation, fragments:


* [MC Glasner], Ruth Glasner, *Averroes'
"Physics" A Turning Point in Medieval Natural
Philosophy*, Oxford University Press, 2009.
doi:10.1093/acprof:oso/9780199567737.001.0001
* [MC Wolfson], Harry Austryn Wolfson, *Crescas' Critique
of Aristotle; Problems of Aristotle's "Physics" in
Jewish and Arabic Philosophy*, (Harvard Semitic series, 6),
Cambridge, MA: Harvard University Press, 1929.



**Short Commentary:**



Arabic


* [SC] Averrois: *Epitome in Physicorum libros*. Madrid:
I.H.A.C.-C.S.I.C. *Corpus Commentariorum Averrois in
Aristotelem*, A XX. Citations take the form 'page:
line'.


### Coming-to-be and Passing-away



**Middle Commentary:** 



English


* [MC GC En] 1958, *On Aristotle's De Generatione et
Corruptione. Middle Commentary and Epitome*, (Averroes'
Aristotle, Corpus Philosophorum Medii Aevi, Corpus Commentariorum
Averrois in Aristotelem series), translated by Samuel Kurland,
Cambridge MA: The Mediaeval Academy of America.
 [Averroes [MC GC] available online].



Arabic


* [MC GC Ar] 2005, *Mittlerer Kommentar zu Aristoteles' De
generatione et corruptione mit einer einleitenden Studie versehen
[...].* Edited by Gudrun Eichner. Paderborn; Munchen; Wien;
Zurich: F. Schoningh.



**Short Commentary:**



English


* [SC GC En] 1958, *On Aristotle's De generatione et
corrvptione Middle Commentary and Epitome.* Translated by Samuel
Kurland. Cambridge, MA: The Medieval Academy of America.



Arabic


* [SC GC Ar] 1992, *Epitome del Libro sobre la
Generacion y la Corrupcion*, 1, edited and
translated by Josep Puig Montada, Madrid: CSIC.