Jacques Maritain Center: Thomistic Institute

Aristotle's De Anima As Source of Aquinas'Anthropological Doctrine

A paper by María L. Lukac de Stier

Although some historians have argued Aristotle's influence on the doctrine of St. Thomas Aquinas1, it is beyond dispute that the latter's doctrine has been built and perfected on the basis of a set of Aristotelian theses, whose main source is De Anima. I will borrow below the enumeration of these theses as set out by Monsignor Guillermo Blanco in the Preliminary Study to the first and only Spanish translation of the Commentary on Aristotle's De Anima, carried out by my good friend Marycel Donadío de Gandolfi2:

1- All bodily substance, living or not living, is composed hylemorphically, i.e. by a formal principle which actualizes, in a definite sense, the potentiality of matter.

2- In living beings, the soul carries out this role of form as primary foundation, intrinsic and constitutive of living beings (actus primus).

3- In the study of living things, we must make a distinction between the substance of the living thing (ousía), its potencies or dynamical powers (dynameis), its acts (enérgueiai) and the objects of its acts. Following the order of the process of epistemic knowledge, our starting point will be the analysis of the objects to eventually come to the substance.

4- According to the degrees of living beings, vegetativity ranks the lowest. It is the basis upon which the others occur, when they do.

5- Sensation as an activity of animals (rational or irrational) is an essentially organic process entailing living corporeity.

6- Our intelligence, as intellectus possibilis (pathetikós nous), is radical indeterminacy and absence of intelligible contents and relies, as far as its objects are concerned, upon fantasy (intelligere phantasticum). This intelligence is spiritual. The realization, or illumination, of the contents of fantasy is the function of an active dynamism, at once more perfect (nobilior) and productive (poietikón)3.

Also following the rationale of Father Leo Elders4, I consider that the aim of the comments by St. Thomas Aquinas with regard to the works of Aristotle was, in every case:

a) to clarify the structure of the work.

b) to analyse its arguments.

c) to reject any interpretations which did not conform to the Aristotelian doctrine (e.gr. Averroist interpretations).

d) to point out agreements and disagreements with the Christian faith.

e) to build up a realistic philosophy in keeping with the Revelation.

Therefore, the aim of this paper is to highlight some basic issues in Aquinas' anthropology, as they appear in the Commentary on Aristotle's De Anima. To do this, in the special case of the possible intellect, we will confront other original works of Aquinas' where, even when his thought is more freely reflected, the Aristotelian origin of the works is apparent.


The first subject we will address with a view to arriving at the definition of soul is the composition of all bodily substance. Taking the Aristotelian text as a starting point (De Anima 412 a 6-11), Aquinas argues that in all bodily substance we can differentiate matter, which in itself is not a particular thing (hoc aliquid) but mere potency to get to be a particular thing; form, which is what actualizes matter; and the compound, which is a particular thing (hoc aliquid), which is complete in being and in kind. Thus, Aquinas concludes:

"Matter then, differs from form in this, that is potential being, form is the 'entelechy' or 'actuality' that renders matter actual; and the compound is the resulting actual being"5.

At once both Aristotle and Aquinas distinguish the living and the non-living among the natural bodies. Aristotle characterizes the ones which are possessed of vitality as those which of themselves take nutriment and grow and decay. Aquinas remarks that this is not a definition but a description through an example. He adds this definition of life:

"Life is essentially that by which anything has power to move itself, taking movement in its wide sense so as to include the movement or activity of the intellect. For we call those things inanimate which are moved only from outside"6.

In this way, the point is reached where Aristotle integrates in the notion of living thing the constitutive principles of all bodily substance, namely matter and form. In De Anima 412 a 15-22, he states:

"Every natural body, then, which possesses life must be substance, and substance of the compound type. But since it is a body of a definite kind, viz, having life, the body cannot be soul for the body is not something predicated of a subject, but rather is itself to be regarded as a subject, i.e., as matter. So the soul must be substance in the sense of being the form of a natural body, which potentially has life. And substance in this sense is actuality. The soul, then, is the actuality of the kind of body we have described"7.

As a comment to this passage, Aquinas claims that by soul must be understood that by which a living thing is alive, and that it exists in a subject, taken in a wide sense to include not only those actual beings which are the subjects of their own accidental modifications but also bare matter or potential being. Regarding the Aristotelian phrase "which potentially has life", Aquinas comments:

"The matter of a living body stands to the body's life as a potency to its act; and the soul is precisely the actuality whereby the body has life... ...it is a substantial actuality or form"8.

Aquinas establishes a difference which does not figure in the Aristotelian text of De Anima, that between an accidental form and a substantial form. The accidental form is super-added to the subject already pre-existing in act, whereas the substantial form is received by the subject only potentially existing, i.e. bare matter. The substantial form gives it simple being (facit esse actu simpliciter). That is the reason why there can only be one substantial form to each thing. By means of this principle, Aquinas opposes that interpretation by Avicebron in Fons Viate according to which an individual man should have many substantial forms, one making him substance, another giving him the body, another by which it has life, etc. Thus, Aquinas concludes:

"It is one and the same substantial form that makes a man a particular thing or substance, and a bodily thing, and a living thing, and so on. For the higher form can give to its matter all that a lower form gives, and more; the soul gives not only substance and body but life also. We must not think, therefore, of the soul and body as though the body had its own form making it a body, to which a soul is super-added, making it a living body; but rather that the body gets both its being and its life from the soul"9.

Thus, eventually, we arrive at the first essential Aristotelian definition of soul:

"The soul, therefore, is the primary act of a physical body potentially possessing life"10.

Aristotle refers to two senses of actuality, comparable to the possession of knowledge and the exercise thereof. The kind of actuality pertaining to the soul is analogous to the possession of knowledge. On commenting on this definition, Aquinas says that his referring to a primary act not only means a differentiation of the soul as act from all the subsequent acts of the living but a distinction, as well, between the soul and the other forms of the elements that act upon the body. He further notes that the phrase "physical body" refers to every organic body, i.e. every natural - not artificial- body equipped with the organs that a living body requires to perform various vital activities. Here is how he asserts it:

"For from this principle (the soul) which is the richest of embodied forms, spring many different activities, so that it requires, in the matter informed by it, a full equipment of different organs"11.

Aristotle chooses plants, the least perfect among the living, to demonstrate that every animate body is organic, meaning it has diversified parts, which amounts to saying that it has different organs performing different functions. And he concludes that, should a definition be found which applies to each and every soul, it would be:

"The soul is the primary act of a physical bodily organism"12.

This definition is nothing if not a modification of the one above, in which - as Aquinas points out- there is no need to add "potentially possessing life", this being implied by the term "organism".

According to this, we can say that the soul is the substantial form of natural organic bodies. In this way of defining the soul, the word "organic" expresses the specific difference of the soul, the other words indicating its genus, since the soul is a special substantial form: the substantial form characteristic of living bodies13. Whence the second definition of soul provided by Aristotle:

"The soul is that whereby we primarily live and perceive and move and understand"14.

Indeed, both definitions are "essential". The first one encloses the essential order of the informed body, and the second the essential order of vital acts, since Aristotle sets out the four main manifestations of vitality. Even before the second definition of soul, Aristotle had argued that the term "to live" is utilized in many senses and that it sufficed for any one of them to be present in something to consider that thing "living". Namely: 1) intellect; 2) sensation; 3) movement or rest in space; 4) movement involved in nourishment, growth and decay15. Each of these senses of living gives rise to a mode of life whose principle is the soul. Aquinas comments upon this question:

"Soul is the one principle underlying the four distinct modes in which life is manifested, namely, the vegetative mode, which belongs to plants and to all living things; the sensitive mode in all animals; the intellectual mode in all men; and fourthly, the mode that is a power to move from place to place, which exists in all the higher animals, both those with senses only and those with intellect as well"16.

However, if the soul is a principle shared by the various modes of life, Aristotle wonders if the principle that animates each one of these modes is to be identified with all the soul or with a part of the soul17. Aristotle's answer is rather diffuse, but in Aquinas' clear and orderly commentary we find a twofold explanation. The first one is based upon the example of the lowest mode of life:

"Where the thing's vitality consists entirely in growing and taking nourishment (as in plants) the vegetative principle is simply the soul or life-principle itself. But where the thing also has sensation this vegetative principle is only a part of the soul. And the same reasoning applies to other cases"18.

The second sets up a general principle:

"Where one only of these principles is found it is the soul itself; but where several are found together each is a part of the soul and the soul itself is named after the principal part, whether sensitive or intellectual as the case may be"19.

Aquinas takes it upon himself to make it clear that, strictly, the soul has no parts, unless by "parts" is construed the faculties, powers or potentialities of the soul20.

Aristotle distinguishes five classes of potentialities: the vegetative, the sensitive, the appetitive, the locomotive and the intellectual21. What first calls our attention is that the appetitive had not been enumerated among the modes of life. We may well wonder why it emerges when distinguishing the potentialities. The Aristotelian explanation is at once simple and confusing: everything sensitive is also appetitive because appetite consists of desire, anger and will. It is the inclination towards which the senses lead,

particularly touch, which exists in all animals. Where there is sensation there is also pain and pleasure; the agreeable and the repulsive emerge22.

As is wont, Aquinas is much more explicit and orderly in his commentary, and he distinguishes clearly the sensitive and the intellectual planes:

"Every form has by nature a certain trend or tendency whence proceed its activities or operations... ...Now the trend that proceeds from a sensible or intellectual form is called sensitive or intellectual desire; as that of any form in nature is called a natural desire. And from this desire follows the activity of local movement. Here then is the explanation we required of the five-fold division of the powers of soul"23.

A few lines below, he will add:

"Sensitivity implies a third power, appetition, which itself divides into three: into desire, in the stricter sense, which springs from the concupiscible appetite; anger, corresponding to the irascible appetite - both of these being in the sensitive part and following sense-knowledge-; and finally will, which is intellectual appetite and follows intellectual apprehension"24.

Here is a perfect example of interpretation which demands an expansion reaching far beyond Aristotle's text, but short of distorting Aristotelian thought, since it concerns doctrines which proceed from its own principles25.

By the same token, in this lectio Aquinas makes it clear that even if Aristotle distinguishes five types of powers, as we have noted, when he refers to the degrees of life in which he places the various kinds of living things, he only refers to four degrees

because, as any one who feels also desires, as explained above, desire or appetite does not constitute a different degree of life26. As to the souls, he only distinguishes three: the vegetative, the sensitive and the intellectual27, owing to a threefold mode of being, the purely immaterial one, the material one and the intermediate being to which the sensitive soul belongs28. All this - types of soul, modes of life and kinds of powers- is much better explained by Aquinas in the Summa Theologiae I, q. 78, a. 1 , where he does not have to follow a text and is free to elaborate his own original arguments. For one thing, the reason for the diversity of souls is explained according to how the operations of the soul outdo the operations of the bodily nature, for all the bodily nature is subject to the soul and is, with respect to it, its matter and instrument29. Aquinas closes this lectio V from Book II of De Anima commenting upon an analogy put forth by Aristotle between the definition of soul and the definition of geometrical figure, thus:

"For in that which is consequent there is always potential for that which is primary, both in figures and in animate beings. As the triangle is contained in the square, so is the vegetative in the sensitive"30.

St Thomas comments as follows:

"In both cases what comes first is potentially in what follows. In figures the three-sided figure exists potentially in the square; for the square is divisible into two triangles. Likewise the sensitive life-principle contains the vegetative, both as potential, as it were, with respect to sensitivity, and also as a certain life-principle in itself. The same holds good with the other figures and the other divisions of the soul"31.

At this point, Aristotle brings up a methodological principle:

"Actions and operations are prior to faculties in the order of thought. And if this is so, one ought first to consider the appropriate objects, which are prior even to the operations, and correspond to them"32.

Commenting upon this methodological principle, Aquinas points out that the objects are: nourishment, with respect to the vegetative; sensible being, with respect to sensation; and intelligible being, with respect to the intellect. He further emphasizes that our potential intellect exists only potentially with respect to the intelligible ones and is made act by form abstracted from sensible images. Nothing is known but is in act, which means that our possible intellect knows itself through the intelligible idea, not by intuiting its essence directly. That is why it is crucial that, regarding knowledge of the soul, we should proceed from that which is more extrinsic, from which intelligible concepts are abstracted through which the intellect perceives itself; namely, that through the objects we should know the actions, through the actions, the powers, and through the powers, the essence of the soul33.

From the above, it is concluded that nourishment - which is the object of the vegetative soul- is to be addressed first together with generation, which is its action. The vegetative soul is addressed first because it is common to all living things34. Similarly, it could be said that generation is the most natural operation of all living things35. Aquinas, after Aristotle, observes as a characteristic of generation that every living being should produce their like. I quote:

"What he [Aristotle] means by living things producing their like is that animals produce animals and plants plants; and more precisely that each species produces its like, men producing men and olive-trees olive-trees. And the reason why living things produce their like is that they may continuously participate, so far as they can, in what is divine and immortal, i.e. that they may become as like to the divine as possible"36.

It should not be thought that Aquinas is adding his own ideas to Aristotle's text, since Aristotle puts it thus:

"...to reproduce one's kind... in order that they may have a share in the immortal and divine in the only way they can"37.

Moreover, Aquinas takes account of the fact that just as there are different degrees of perfection in the same being that passes from potency to act, so there are different degrees of perfection in beings. From this, he concludes that the more perfect a being is, the more it is like the most perfect forms, so that any being which is in a lower degree wishes to be like the higher forms. That is why Aristotle says:

"To this extent do they participate as far as they are able, in the imperishable and the divine. For this all things seek after, doing all that they do by nature for the sake of this"38.

Here is an outline of a hierarchical order of all the universe, which Aquinas timidly includes in the Commentary on Aristotle's De Anima39, which he had developed at length in Contra Gentes when he had referred to man as the end of all generation40. In Contra Gentes itself, he had developed the consideration of the human soul as horizon and boundary between the corporeal and incorporeal41. However, this corresponds, rather, to St. Thomas the theologian, who attempts to understand man as a creature that stands as a link between the spirits and the bodies, and, besides, denotes the Platonic-Plotinic influence which comes down to him through the Liber de Causis. This subject would deserve another paper; I only mention it here to show Aquinas' fidelity to the Aristotelian text and to the consciousness he has of his own task as a commentator.

After discussing the object and the act of vegetative life, Aristotle shows the relationship between the activities attributed to the vegetative principle and the soul. Thus, he writes:

"The soul is the cause and principle of the living body. Now these words can be used in many ways. The soul, however, is a cause in three established senses: for it is that whence comes movement; that 'for the sake of which'; and as the essence of living bodies"42.

Aquinas, in commenting this passus, claims that two arguments are utilized to prove that the soul is the cause of the living thing as its form. The first:

"The cause of anything as its 'essence', i.e., form, is the same as the cause of its being, for everything has actual existence through its form. Now it is the soul that gives being to living things; for their being is precisely their life, which they have from the soul. Hence, the soul causes the body as its form"43.

I quote the second argument:

"The actuality of anything is the immanent idea (ratio) and form of the thing as in potency. Now the soul, as we have seen, is the living body's actuality. Therefore it is the form and immanent idea of the living body"44.

The second sense alluded by Aristotle ("for the sake of which") is identified with the end, insofar as the soul is the final cause of the living thing. St. Thomas explains it so:

"For Nature, like mind, acts for a purpose, as was shown in Book II of the Physics. But the mind, in its constructions, always orders and arranges materials in view of some form. So also, then, does Nature. If then the soul is the living body's form, it must also be its final cause. Moreover, the soul is the end not only of living bodies, but also of all sublunary natural bodies. For it is evident that all such bodies are, as it were, instruments of soul - not only of animal's souls but of the plant soul as well"45.

Lastly, Aquinas also comments that the soul is the source of the body's movement:

"The form of every natural body is the principle of the characteristic movement of that particular kind of body. Now certain movements are characteristic of living bodies; such, for instance, as that by which animals move themselves about from place to place, though this, to be sure, is not found in all living things. Similarly, sensation involves a certain alteration of the body not found except in beings that have soul. So too with growth and decay; these movements imply the use of food and therefore also a soul. The soul, then, is the principle of all these movements"46.

Aristotle brings the subject of vegetative life to a close addressing two issues. Firstly, he distinguishes three factors with respect to nourishment: what is nourished, that by which it is nourished, and that which nourishes. He resolves it as follows:

"What nourishes is the primary soul, that which is nourished is the body containing it, and that by which it is nourished is food"47.

Aquinas, in commenting upon this, adds that the vegetative soul is nourishment principle as the main agent, whilst food is such as instrumental agent48.

The second question is to define the vegetative soul. I quote from De Anima:

"Since all things are rightly named from their end [of this soul] is to have generated another being like itself, then the primary soul is generative of what is like itself."49.

In the commentary, Thomas expands the text so that the definition is understood better. With this end in mind, he quotes the three vegetative activities, which are found in a certain order. First nourishment, by which living things stay alive. Second, and as a more perfect activity than the previous one, growth, by which a living thing increases and perfects itself both in quantity and in capacity. Third, the last and most perfect of all vegetative activities, reproduction, by which a living thing, complete in itself, gives its existence and perfection to one like itself. From this explanation, it may be understood that every activity of the vegetative soul tends towards generation as its goal, whence is correct to define the vegetative soul "as that which is reproductive of another, like to itself in kind"50.

We have devoted so much space to the vegetative life because it is the basis of every living thing. In this way, I prove the fourth thesis set out in the introduction to this paper, namely that the vegetative life comes at the lowest level, as a basis on which the

others occur, when they do. Besides, Aristotle himself argues in the penultimate chapter of Book III of De Anima:

"Every living thing, then, must have the nutritive soul, and in fact has a soul from its birth until its death; for what has been born must have growth, a highest point of development, and decay, and these things are impossible without food. Of necessity, then, a vegetative power is found in all that is born and dies"51.

In turn, Aquinas comments on the fragment thus:

"All beings that participate in any way in soul must, from the first moment of their generation until their final corruption, have some share in the vegetative principle, indicating by these terms that he speaks especially of animate beings which come to being through generation and cease through corruption... No animate and generated being can exist without passing through the stages of growth, maturity and decline. And these all presuppose food... And as it pertains to the vegetative principle to make use of food, this principle must be common to everything that is born and that dies; and must be related to the other parts of the soul as the foundation they all presuppose"52.


In the following pages, we will discuss more briefly what is involved in sensitivity, whose basic difference with vegetative life consists in the inclusion of knowledge - only sensible knowledge, naturally. Aristotle declares:

"Sensation consists, as has been said, in being moved and acted upon; for it is held to be a sort of change of state"53.

A few lines on, he adds:

"But since we speak of perceiving in two senses (for we may say that that which has the power of hearing and seeing hears and sees, even if it happens to be asleep, as well as when the faculty is actually operative), so the term sensation must be used in two senses, as potential and as actual. Similarly, to perceive means both to possess the faculty and to exercise it"54.

In the comment, Aquinas points to another Aristotelian quotation which adds new concepts on the sensitive soul:

"The sensitive soul is clearly not actually, but only potentially, the sense-object. That is why sensation will not occur without an exterior sense-object"55

In lectio 12, St. Thomas addresses knowledge as such and the distinction between sensible and intellectual knowledge. Firstly, let us ask: what is knowledge?

"Knowledge implies that the thing known is somehow present in the knower (present by its similitude); the knower's actuality as such being the actuality of the thing known"56.

Now, and through Aquinas' text, we can have access to the difference between sensitive and intellectual knowledge:

"The sense-faculty receives a similitude of the thing sensed in a bodily and

material way, whilst the intellect receives a similitude of the thing understood in an incorporeal and immaterial way... Clearly, then, a thing's similitude as received in sensation represents the thing as an individual; as received, however, by the intellect it represents the thing in terms of a universal nature. That is why individuals are known by the senses, and universals by the intellect"57.

Resuming the methodological schema applied to vegetative life and before he determines what is sense, Aristotle addresses sense-objects proper to each sense, as objects are prior to potencies. On this question, we read in De Anima:

"We speak of a sense-object in three ways: two [kinds of sense-objects] are perceptible essentially; one, incidentally. Of the two former, one is proper to each sense, the other common to all"58.

Commenting on this text, Aquinas adds:

1- "He means by proper sense-object what is perceived by one sense and by no other, and in respect of which the perceiving sense cannot err; thus it is proper to sight to know color, to hearing to know sound, to taste to know flavor or savor. Touch however, has several objects proper to itself: heat and moisture, cold and dryness, the heavy and the light, etc."59.

2- "The common sense-objects are five: movement, rest, number, shape and size. These are not proper to any one sense but are common to all; which we must not take to mean that all these are common to all the senses, but that some of them, i.e. number, movement and rest, are common to all. But touch and sight perceive all five"60.

3- "To be a sense-object incidentally can be understood with an example: "We might call Socrates incidentally a sense-object because it happens to be white: that is sensed incidentally (sensitur per accidens) which happens to belong to what is sensed absolutely (sensitur per se). It is accidental to the white thing, which is sensed absolutely, that it should be Socrates; hence Socrates is a sense-object incidentally. He does not, as such, act upon the sense at all"61.

4- "A difficulty arises here about the distinction between common and incidental sense-objects. For if the latter are only perceived in so far as the proper objects are perceived, the same is true of the common sense-objects: the eye would never perceive size or shape if it did not perceive color"62.

At this point, St. Thomas proceeds by grafting notions which are alien to Aristotle, which he picked up from the Arabian sources63. Avicena had already continued the legacy of the Arabian philosophers and himself developed what he calls vis cogitans and cogitativa in some passages of his treatise on the soul64. It was him who discovered an analogous sense in animals, which he called "estimative" capable of perceiving intentions which were not apprehended by any of the external senses.

Thus, Aquinas holds that to explain how the incidentally sensitive is known it is a necessity for it to be known in itself by some other cognitive power of the senser, which means either another sense or the intellect. And here he introduces the Arabian notion, which St. Thomas makes his own, inasmuch as he adds: "or the cogitative faculty (vis cogitativa), or natural instinct (vis aestimativa)" 65. Aquinas extends his explanation with examples:

"If this apprehension is of something individual, as when, seeing this particular colored thing, I perceive this particular man or beast, then the cogitative faculty (in the case of man at least) is at work, the power which is also called 'the particular reason' because it correlates individualized notions, just as the 'universal reason' correlates universal ideas"66.

He goes on to explain that this power, introduced by him and alien to the Aristotelian text, pertains to sensitivity:

"For the sensitive power at its highest - in man, in whom sensitivity is joined to intelligence- has some share in the life of intellect. But the lower animals' awareness of individualized notion is called natural instinct, which comes into play when a sheep, e.g., recognizes its offsprings by sight, or sound, or something of the sort"67.

Finally, St. Thomas establishes the difference between the cogitative and the estimative:

"The cogitative faculty differs from natural instinct. The former apprehends the individual thing as existing in a common nature, and this because it is united to intellect in one and the same subject. Hence it is aware of a man as this man, and this tree as this tree; whereas instinct is not aware of an individual thing as in a common nature, but only in so far as this individual thing is the term or principle of some action or passion. Thus, a sheep knows this particular lamb, not as this lamb, but simply as something to be suckled; and it knows this grass just in so far as this grass is its food. Hence, other individual things which have no relation to its own actions or passions it does not apprehend at all by natural instinct. For the purpose of natural instinct in animals is to direct them in their actions and passions, so as to seek and avoid things according to the requirement of their nature"68.

Aristotle also asks himself how form is received in sensation. Here is his answer:

"We must understand as true generally of every sense that sense is that which is receptive of the form of sensible objects without the matter, just as the wax receives the impression of the signet-ring without the iron or the gold, and receives the impression of the gold or bronze, but not as gold or bronze"69.

Aquinas comments this text turning it into a principle:

"The recipient receives the form in a mode of existence other than that which the form has in the agent... it is thus that a sense recieves form without matter, the form having, in the sense, a different mode of being from that which it has in the object sensed. In the latter, it has a material mode of being (esse naturale), but in the sense, a cognitional and spiritual mode"70.

As a fine observer of reality, Aristotle warns that, even in the absence of the sense-objects, something remains in the senses. So he expresses in De Anima:

"Hence, in the absence of the sense-objects there remains sensations and phantasms in the sense-powers"71.

Aquinas comments on this:

"The sense-organ as such receives a form from the sensible object, but without matter, which is why, when the object passes away, we retain sensations and images, i.e., the appearances in and by which animals somehow sense things"72.

Even if the last texts would be the perfect link to move on to comment on the internal senses, we will not address this subject because, despite Aristotle's concern with the imagination and common sense, he did not leave behind a doctrinal body as such. It can be said that for him there is no series of faculties but a general interior sensibility of which fantasy, or the imagination, is a function which, in turn, conditions both the understanding of the concrete and abstract thinking. In his original works, Aquinas elaborates his own doctrine of internal sensible knowledge based on contributions by Avicena, Averroes and St. Albert Magnus. Mostly, he includes Avicena's innovations, only to curtail the number of internal senses to four, following the number stipulated by Averroes73.


As stated, we go on to consider intellectual knowledge, which in De Anima always appears compared with sensible knowledge. Among so many others, we find this expression of Aristotle's:

"Now it should be evident that rational judgement and sensation are not the same. The latter is in all animals, the former in but a few"74.

Aquinas is much more explicit in his commentary, such as he is throughout Book III of De Anima. I quote:

"The difference between intellectual and sensuous cognition is that the latter is corporeal. Sensation cannot occur apart from the act of a bodily organ, whereas understanding, as we shall prove later, does not take place by means of such an organ"75.

Although he establishes the difference between intellectual cognition and sensuous cognition, a few lines above he had established the dependence of the intellect and will with respect to the sensible faculties:

"Thus any injury to the bodily organ of the imagination will impede the intellect; and the will is incited towards choosing or not choosing by sensuous desire"76.

Aristotle establishes yet another difference, this time between sensible cognition and intellectual cognition, based on the truth that one or the other can accomplish:

"Sensation is always true of its own proper objects, and is found in all animals, whereas intelligence is sometimes accompanied by error, and is found in no species that lack reason"77.

Aquinas also takes care of the issue by explaining that, unlike the senses with respect to their proper object, understanding can be correct or incorrect. Correct understanding occurs in the sciences which deal with speculative and necessary things, or in right reason, which deals with contingent activities, or in the true opinion, which is concerned with the objects of the other two. Incorrect understanding encompasses false science, imprudence and false opinion. Hence, he concludes that the sense and understanding are not the same. And, should someone object that correct understanding could at least amount to sensation, Aquinas makes it clear that man has access to intelligible truth by means of rational discourse, whereas immaterial substances which have a higher intellectual degree apprehend truth immediately, without the need to reason. Therefore, there is no way in which understanding can be the same as sensing78.

In Book III, Chapter 4 of De Anima, Aristotle undertakes an overall analysis of the intellect. This is the beginning of Book III for the Arabo-Latin version of De Anima.

And this is also the rationale adopted by Father Gauthier for the Leonine edition. We have followed the division made by Pirotta, which is the one the Dumb Ox Books edition of Thomas's Commentary on Aristotle's De Anima adopts. Aristotle opens the chapter like this:

"Concerning that part of the soul (whether it is separable in extended space, or only in thought) with which the soul knows and thinks, we have to consider what is its distinguishing characteristic, and how thinking comes about"79.

Commenting the text, Aquinas says:

"It is now time to discuss that part of the soul 'by which it knows', i.e., understands, and 'is wise'... And he [Aristotle] keeps two ends in view. One is to examine how this part of the soul differs from the others, if it can be separated from them in thought. And, as potencies are known from their acts his second aim is to examine the act of understanding itself, i.e., how intellectual activity is completed"80.

Aristotle continues to compare the intellect with sensation, based on the kind of reception of the respective objects. I quote:

"For if understanding is like sensing, it will be some kind of reception from an intelligible object, or some thing of that nature. It must then be impassible and yet receptive of a species, which it must already be potentially but not actually: and as the sense faculty stands to the sense-object, so will the intellective to the intelligible"81.

Aquinas interprets as follows:

"Yet sensing resembles a passion inasmuch as the sense is potential with respect to its object; for it receives sensible impressions. So far then as understanding resembles sensation the intellect too will be impassible (taking passivity in the strict sense), yet will it show some likeness to what is passive, in its receptivity to intelligible ideas; for these it possesses only potentially, not actually. Thus, as sensitive life is to sensible objects, so is the intellect to intelligible objects, each being potential with respect to its object and able to receive that object"82.

Aristotle continues with his analysis, seeking to define the nature of the intellect:

"What then is called the 'intellect' of the soul (I mean the mind by which the soul forms opinions and understands) is not, before it understands, in act of any reality. Hence, it is a reasonable inference that it is not involved in the body"83.

St. Thomas interprets that Aristotle strives to deduce the nature of the potential intellect (intellectus possibilis) and holds that, precisely, as it is not in act of understanding but only in potency, and to know all things in potency, it cannot be compounded or mixed with bodily things, as Empedocles thought, but rather separated from such things, as held by Anaxagoras. Aquinas introduces an argument which is not in the text he is commenting:

"Anything that is in potency with respect to an object, and able to receive it into itself, is, as such, without that object... Since then it naturally understands all sensible and bodily things, it must be lacking in every bodily nature; just as the sense of sight, being able to know color, lacks all color"84.

From what has been expounded, St. Thomas deduces two things: 1) that the nature of the intellect is to be in potency with respect to all things because it is able to know universally all sensible natures; 2) our intellect is not in act any thing before understanding85.

To comment the last part of the Aristotelian quotation, he deduces from the last argument stated above. I quote:

"If the mind's universal capacity for knowledge implies its intrinsic distinction from all the corporeal natures that it knows, for the same reason it can be argued that the mind is not 'involved in the body', i.e., that it has no bodily organ, as the sensitive part of the soul has"86.

Aristotle compares again the sensitive with the intellective power touching impassibility. I quote:

"That the impassibility of the sensitive faculty is not like that of the intellective faculty, is evident from the organs and from sensation itself. For the same cannot receive an impression from too violent a sense-object - e.g., a sound from very great sounds, whilst from overpowerful odours there comes no smell. But when the intellect understands something highly intelligible, it does not understand what is inferior to these less than before, but more so. For whereas the sensitive faculty is not found apart from the body, the intellect is separate"87.

This text gets St. Thomas's attention because Aristotle's last, ambiguous expression gave rise to many erroneous interpretations which Aquinas wants to prevent and refute. With this in mind, he introduces arguments which extend and clarify the overly compressed, obscure Aristotelian definition.

As regards impassibility, Aquinas only restates Aristotle's claims, i.e. that the senses are indirectly affected by their objects, through their organs, when there is an excess on the part of the object, as too loud a sound can deafen, or too bright a color can dazzle. Instead, the intellect, not having organs that can be affected by an excess, is not weakened in his activity by a greater intelligibility of the object. On the contrary, it is strengthened to understand that which is less intelligible. On the other hand, the intellect is weakened, indirectly, by the lesion of a bodily organ because the operation of the intellect presupposes that of the sense.

Finally, the cause of the difference between the sensitive and the intellectual powers is based on the fact that sensitivity does not exist without the body, whereas the intellect is separate88.

At once, Aquinas issues a warning about the mistake incurred by those who believed that "est separatus" meant that the intellect existed separately from the body as a separate substance (sicut una de substantiis separatis). We reproduce the argument proposed by St. Thomas to expose the untenability of such a position:

"It is clear that the actually intelligent being is this particular man... if he does understand anything he must do so in virtue of some principle in him of this particular activity of understanding; which is the potential intellect to which the Philosopher refers when he says: 'I mean the mind by which the soul understands and forms opinion'. The potential intellect then is precisely that by which this particular man understands... But it is quite impossible for the agent to exist separately from that which, formally and immediately, he is an agent... It follows that the agent and the proper and immediate principle of his activity must exist together in one act; which could not be if they were separate beings. Hence, the impossibility of a separation in being of an agent from its formal principle of activity"89.

Immediately, Aquinas presents the arguments sought by those who wrongly interpreted the Aristotelian expression so that the possible intellect, which they called separate substance, is united to us for their understanding to be our understanding:

"They said then that the form of the potential intellect, that by which it is brought into act, was the intelligible idea, and that the subject possessed of this idea was a kind of phantasm produced by ourselves. In this way, they said, the potential intellect is linked with us through its form"90.

Nevertheless, this argument does not demonstrate the unity of the intellect and us. And St. Thomas proves it as follows:

"The potential intellect is only united with an intelligible object in the degree that it is in act... Therefore, the intelligible idea cannot be the form of the potential intellect until it is actually understood; and this cannot happen until it is disengaged from phantasms by abstraction. Hence, precisely in the degree that it is joined to the intellect it is removed from phantasms. Not in this way therefore could a potential intellect be united with us"91.

St. Thomas adds that those who maintained the erroneous argument were led astray by a "fallacia accidentis". But even if we accepted that in that way some union between the possible intellect and ourselves was achieved, that union would not bring us under-standing but, rather, it would allow others to understand us. Not because in the eye there is an intentional likeness of a colored wall does the color happen to see but, rather, it is seen. St. Thomas applies this example to the intelligible-intellect relationship:

"Therefore if the intelligible idea in the intellect is a sort of likeness of our phantasms, it does not follow that we perceive anything intellectually, but rather that we - or more precisely our phantasms- are understood by the separated intellectual substance"92.

Should this position be maintained, it would follow that this man does not understand, which contradicts, according to Aquinas, Aristotle's position such as he manifests in this chapter of De Anima, when he says that the intellect is that by which the soul understands.

To put an end to this lectio, St. Thomas insists that Aristotle calls the intellect separate because it has no organ, unlike the sense. This is because the human soul, on account of its superiority, transcends the capacity of bodily matter. That is the reason why some operation pertains to it in which it does not communicate with the bodily substance. Hence, the power related to that operation should not possess a bodily organ, and in this respect alone can the intellect be understood to be separate.


Evaluating the Commentary on Aristotle's De Anima, we can say that Aquinas, even when he inserts his own arguments, follows Aristotle's text faithfully. This also means that the subject of the intellect is always addressed as it relates to its operation and compared with sensuous cognition. He does not stress, as in his original works -Contra Gentes, the Prima Pars of the Summa Theologiae, the Quaestiones De Anima and the opuscule De Unitate Intellectus contra Averroistas- that understanding as an intellective principle is the form of the human body. Hence, as I announced at the outset when I stated the aim of this paper, in the particular case of the potential intellect, I will set aside the Commentary on Aristotle's De Anima in order to set out the basic arguments concerning the form of the human body. From those original works, the arguments proving that the potential intellect is not one for all men, not expounded in the Commentary, could also be analyzed. But, due to time constraints, this would be subject for another paper93.

Let us move on to the analysis of the intellective principle uniting the human body as form. Since the argumentation for this is repeated throughout the different works - although some given aspects are emphasized, diverse in each case and in accordance with the structure of each particular work- we will attempt to summarize the common arguments, highlighting the most relevant ones and bearing in mind the time constraints which this exposition must meet.

Proof that understanding, or the intellective principle, is a power of the soul, which, in turn, is the form of the human body:

First argument: That by which something operates primarily is the form of the operator. ("Illud quo primo aliquid operatur est forma operantis", De Unit., Chapter I, 193; "illud quo primo aliquid operatur, est forma eius cui operatio attribuitur", S.Th. I, q. 76, a. 1, c; "Id quo aliquid operatur, oportet esse formam", De Unit., Chapter III, 38-40).

Second argument: Nothing acts but insofar as it is in act, and nothing is in act but by that which is its form. ("Nihil agit nisi secundum quod est actu; actu autem non est aliquid nisi per id quo est forma eius", C. Gent., II, 59; "nihil agit nisi secundum quod est actu: unde quo aliquid est actu, eo agit", S. Th. I, 76, a. 1, c; "unumquodque agit in quantum est actu; est autem unumquodque actu per formam: unde oportet illud quo primo aliquid agit esse formam", De Unit., Chapter III, 38-40).

Third argument: The nature of every being is manifested through its operation. But the operation proper to man, as such, is understanding. It is crucial that the human species be constituted from that which is principle of this operation. ("Natura uniuscuisque rei ex eius operatione ostenditur. Propria autem operatio hominis, inquantum est homo, est intelligere... Oportet quod homo secundum illud speciem sortiatur, quod est huius operationis principium", S.Th. I, q. 76, a. 1, c; "id igitur per quod hic homo speciem sortitur forma est. Unumquodque autem ab eo speciem sortitur, quod est principium proprie operationis speciei; propria autem operatio hominis, in quantum est homo, est intelligere", De Unit., Chapter III, 322-327; "forma autem per quam aliquid habet speciem, est actus primus... Homo speciem sortitur per hoc quod est rationalis et intellectum habens", C. Gent., II, 59).

Fourth argument: This principle, in virtue of which we at first understand, we call understanding, or intellective soul, and is the form of the body. ("Hoc principium quod primo intelligimus, sive dicatur intellectus, sive dicatur anima intellectiva, est forma corporis", S.Th. I, q. 76, a. 1, c; "Principium autem quo intelligimus est intellectus, ut Aristotelis dicit; oportet igitur ipsum uniri corpori ut formam", De Unit., Chapter III, 329-332; "Homo autem intelligit, et non nisi per intellectum... Oportet igitur intellectum possibilem formaliter uniri nobis", C. Gent., II, 59).

Once the four basic arguments common to the texts have been set out briefly, it is advisable to summarise both the objections, or counterarguments, wielded by Averroes and his followers and Aquinas' replies to them. As each work has its own intentions, it stands to reason that there are but a few objections to be found in the Summa Theologiae - and these of a very general nature-, which Aquinas answers briefly and concisely to lay the foundations of the doctrine, with no major debates; in Contra Gentes, Aquinas' counterarguments are extended and deepened, indicating in more detail their procedence and refuting them more subtly. Lastly, in De Unitate Intellectus the controversial character is stressed, making reference to Aristotelian texts throughtout to bring out, in a very detailed manner, the erroneous interpretations on the part of Averroes and his disciples, together with the correct interpretation that must be made of these texts.

First Averroist objection: With De Anima III as a basis, where Aristotle says that understanding is separate and not mixed with the body, that it is simple and impassive, they claim that understanding is not the act of a body nor is it united to the body as form94.

Refutation: St. Thomas, performing a comparative analysis of Aristotle's texts, demonstrates that when the latter speaks about the understanding as separate he means that it is not the power of any bodily organ. ("Philosophus dicit in III De Anima, quod intellectus est 'separatus' quia non est virtus alicuius organi corporalis", S.Th., I, q. 76, a. 1, ad 1)95.

Aquinas also demonstrates that there is no contradiction in the fact that the human soul is form of the body and that the intellect is separate, since the intellect, which is a power of the soul, is not an act of the body as is the soul itself. For the soul is not the form of the body by virtue of its powers but of its very essence. ("Intellectus, quem Aristoteles dicit potentiam animae, non est actus corporis: neque enim anima est actus corporis mediantibus suis potentiis, sed anima per se ipsam est actus corporis dans

corpori esse specificum", De Unit., Chapter I, 490-495). Therefore, the essence of the soul and its power must be distinguished. According to its essence, it gives the "esse" to such a body and, according to its power, it performs its own operations. ("Est enim in anima considerare et ipsius essentiam, et potentiam eius. Secundum essentiam quidem suam dat esse tali corpori; secundum potentiam vero operationes proprias efficit", C. Gent., II, 69). Finally, if the soul is according to its substance form of the body, it is not necessary that all its operations be carried out by means of the body so that all its powers be acts of the body, since the human soul is not a form completely immersed in matter, being the highest form among the others. This is why it is able to perform operations without the body, that is, becoming independent from it in the operation because the soul does not depend upon the body in its being either. ("Iam enim ostensum est quod anima humana non sit talis forma quae sit totaliter immersa materiae, sed est inter omnes alias formas maxime supra materiam elevata. Unde et operationem producere potest absque corpore, idest, quasi non dependens a corpore in operando: quia nec etiam in essendo dependet a corpore", C. Gent., II, 69).

Second Averroist objection: Since the potential intellect receives all forms from sensible things, it is necessary that it lacks all. If, then, understanding united the body as form, given that every body has its particular nature, it would follow that understanding acquires a certain nature, contradicting what we stated above and not being able to know all things nor know them as universals96.

Refutation: St. Thomas, in the Summa Theologiae and in Contra Gentes, simply points out that it is enough to determine that the intellective power is not an act of the body to prove that man can understand with his intellect all things and know them in an immaterial and universal manner. ("Sufficit ad hoc quod homo possit intelligere omnia per intellectum et ad hoc quod intellectus intelligat immaterialia et universalia, quod virtus intellectiva non est corporis actus", S.Th. I, q. 76, a. 1, ad 2). In two parts of De Unitate Intellectus, he addresses this issue. In Chapter I, he does so by arguing that the intellect does not contain any particular nature of those sensible natures it knows

because its only nature consists in being possible, i.e being in potency with respect to all intelligible things. ("Concludit ergo quod intellectus antequam intelligat in actu nihil est actu eorum quae sunt", De Unit., Chapter I, 393-395)97. In Chapter III, he denies that the intellect can be material form and holds, following the Aristotelian doctrine, that if the intellect is not act of any organ, it remains not only immaterial but also recipient of an immaterial mode and understands itself. That is why Aristotle holds that it is not the whole soul but only understanding that is the site or receptacle of forms. ("Non enim dicimus animam humanam esse formam corporis secundum intellectivam potentiam, quae secundum doctrinam Aristotelis nullius organi actus est: unde remanet quod anima, quantum ad intellectivam potentiam, sit immaterialis et immaterialiter recipiens et se ipsam intelligens. Unde et Aristotelis signanter dicit quod anima est locus specierum 'non tota sed intellectus'", De Unit., Chapter III, 378-386)98.

Third Averroist objection: If understanding were part of the soul which is form of the body, it would seem that, the body being corruptible, understanding would also be, of necessity, corruptible.

Refutation: Aquinas replies saying that it is evident that the form which has operations proper to itself and independent of matter, rather than form of the compound, is the form that gives the "esse" to the compound, so that the soul does not receive the "esse" because of its presence in the compound but rather gives form to it. Therefore, it is not necessary that this form which gives the "esse" to the compound and does not live by it corrupts itself when the compound does. ("Forma igitur quae habet operationem secundum aliquam sui potentiam vel virtutem absque communicatione suae materiae, ipsa est quae habet esse, nec est per esse compositi tantum sicut aliae formae, sed magis compositum est per esse eius. Et ideo destructo composito destruitur illa forma quae est per esse compositi, non autem oportet quod destruatur ad destructionem compositi illa forma per cuius esse compositum est, et non ipsa per esse compositi", De Unit., Chapter I, 644-653). And in the Summa Theologiae he refutes saying: "Quod anima illud esse in quo ipsa subsistit communicat materiae corporali, ex qua et anima intellectiva fit unum, ita quod illud esse quod est totius compositi, est etiam ipsius animae. Quod non accidit in aliis formis, quae non sunt subsistentes. Et propter hoc anima humana remanet in suo esse, destructo corpore", S. Th. I, q. 76, a. 1, ad 5).

I am aware that there are still many subjects in Aquinas' anthropology which have not been addressed, but I have strived, above all, to stick to the subject of this paper and its aim. I hope I have met those expectations as best I could and that I have not disappointed you.

María L. Lukac de Stier

Universidad Católica Argentina - CONICET

Buenos Aires


1 Cf. Jacques Chevalier, "Trois conférences d'Oxford", Les Lettres, 1927, p. 429; E. Gilson, "Cajetan et l'existence", Tijdschrift voor philosophie 15, 1953, 284; J. Owens, "Aquinas as an Aristotelian Commentator", St. Thomas Aquinas on the Existence of God. Collected papers of Joseph Owens, edited by Catan, Albania, 1980, 1-19.

2 Cf. Sto. Tomás de Aquino, Comentario al "Libro del Alma" de Aristóteles, translation and annotation by María Donadío Maggi de Gandolfi, Preliminary Study by Monsignor P. Blanco, Fundación Arché, Buenos Aires, 1979.

3 This intellect would later be called agent intellect. Aristotle did not use the phrase "nous poietikós", even though he has thus described this intellect. It could be said that Alexander of Afrodisia first used this expression.

4 Cf. Leo Elders, Santo Tomás de Aquino Hoy, Chapter I, "Santo Tomás de Aquino y Aristóteles", Sociedad Tomista Argentina, Buenos Aires, 1989, pp. 11-25; "Le commentaire de Saint Thomas d'Aquin sur le De Anima d'Aristote, L'Anima nell'antropologia di S. Tommaso d'Aquino, Massimo, Milano, 1987, pp. 33-51.

5 Sentencia libri de Anima, II, 1, 215. For the present paper, we have used the English version, Commentary on Aristotle's De Anima, translated by Foster-Humphries, Dumb Ox Books, Notre Dame, Indiana, 1994.

6 Commentary..., II, 1, 219.

7 For the present paper, we have used the English version of De Anima, translated by Hett, Loeb Classical Library, Harvard University Press, reprinted 1975.

8 Commentary..., II, 1, 222-223.

9 Commentary..., II, 1, 225.

10 De Anima II, 1, 412 a 28.

11 Commentary..., II, 1, 230.

12 De Anima II, 1, 412 b 4-6.

13 Cf. Marcos Manzanedo, O.P., "La naturaleza del alma según Santo Tomás", L'Anima nell'antropologia de S. Tommaso d'Aquino, Massimo, Milano, 1987, pp. 303-312.

14 De Anima II, 2, 414 a 13.

15 De Anima II, 2, 413 a22: "But the word living is used in many senses, and we say that a thing lives if any one of the following is present in it: mind, sensation, movement or rest in space, besides the movement implied in nutrition and decay or growth".

16 Commentary... II, 3, 261.

17 De Anima II, 2, 413 b 13-15.

18 Commentary..., II, 4, 262.

19 Op. cit., II, 4, 270.

20 Op. cit., II, 5, 279.

21 De Anima II, 3, 414 a 29-32.

22 De Anima II, 3, 414 a 32-414 b 6.

23 Commentary..., II, 5, 286.

24 Ibid., II, 5, 288.

25 On the subject of an accurate or alien interpretation of the Aristotelian text, see Leo Elders, Sto. Tomás de Aquino hoy, Chapter I, "Sto. Tomás y Aristóteles", Sociedad Tomista Argentina, Buenos Aires, 1989, p. 11-25. Also see Martha C. Nussbaum-Amélie Oksemberg, Rorty (ed.), Essays on Aristotle's De Anima, Oxford Clarendon Press, 1992.

26 Commentary..., II, 5, 287.

27 Ibid., II, 5, 285.

28 Ibid., II, 5, 281-284.

29 Cf. S. Th. I, q. 78, a. 1, c: "diversae animae distinguuntur secundum quod diversimode operatio animae supergreditur operationem naturae corporalis; tota enim natura corporalis subiacet animae, et comparatur ad ipsam sicut materia et instrumentum".

30 De Anima II, 3, 414 b 28-32.

31 Commentary...II, 5, 298. Again see a more solid and developed explanation in S.Th. I, q. 76, a. 3, c. in fine.

32 De Anima II, 4, 415 a 16-21.

33 Cf. Commentary..., II, 6, 304-308.

34 Cf. Commentary..., II, 7, 310.

35 Cf. Ibid., II, 7, 313.

36 Cf. Ibid., II, 7, 314.

37 De Anima II, 4, 415 a 28-415 b 3.

38 Ibid.

39 Commentary... II, 5, 288: "Here we have to consider that the completeness of the Universe requires that there should be no gaps in its order, that in Nature there should everywhere be a gradual development from the less to the more perfect".

40 Cf. Contra Gentes III, 22: I quote in the way of summary: "ultimus igitur finis generationis totius est anima humana, et in hanc tendit materia sicut in ultimam formam. Sunt ergo elementa propter corpora mixta; haec vero propter viventia; in quibus plantae sunt propter animalia; animalia vero propter hominem. Homo igitur est finius totius generationis".

41 Contra Gentes II, 68: "Et inde est quod anima intellectualis dicitur esse quasi quidam horizon et confinium corporeorum et incorporeorum, inquantum est substantia incorporea, corporis tamen forma".

42 De Anima II, 4, 415 b 8-12.

43 Commentary...II, 7, 319.

44 Ibid., 320

45 Ibid., 321-322.

46 Commentary...II, 7, 323.

47 De Anima II, 4, 416 b 21-23.

48 Cf. Commentary II, 9, 346.

49 De Anima II, 4, 416 b 23-25.

50 Commentary...II, 9, 347.

51 De Anima III, 12, 434 a 22-26.

52 Commentary... III, 17, 847-848.

53 De Anima II, 5, 416 b 32-417 a 2.

54 De Anima II, 5, 417 a 9-14.

55 Commentary...II, 10, 354.

56 Commentary...II, 12, 377.

57 Ibid.

58 De Anima II, 6, 418 a 7-11.

59 Commentary...II, 13, 384.

60 Ibid., 386.

61 Ibid., 387.

62 Ibid., 388.

63 See Abelardo Lobato, "Anima quasi horizon et confinium", L'Anima nell'antropologia di S. Tommaso d'Aquino, Massimo, Milano, 1987, 53-80.

64 Avicena, De Anima I, 5, p.89, Van Riet.

65 Commentary..., II, 13, 395.

66 Ibid., 396.

67 Ibid., 397.

68 Commentary...II, 13, 398.

69 De Anima II,12, 424 a 17-22.

70 Commentary...II, 24, 553.

71 De Anima III, 2, 425 b 24-26.

72 Commentary...III, 2, 590.

73 Cf. S. Th. I, q. 78, a. 4: "Utrum interiores sensus convenienter distinguantur".

74 De Anima III, 3, 427 b 6-8.

75 Commentary...III, 4, 622.

76 Ibid., 621.

77 De Anima III, 3, 427 b 10-14.

78 Cf. Commentary...III, 4, 630-631.

79 De Anima III, 4, 429 a 10-13.

80 Commentary...III, 7, 672, 674.

81 De Anima III, 4, 429 a 13-18.

82 Commentary...III, 7, 676.

83 De Anima III, 4, 429 a 22-24.

84 Cf. Commentary...III, 7, 680.

85 Cf. Ibid., 681-682.

86 Commentary...III, 7, 684.

87 De Anima III, 4, 429 a 29-429 b 5.

88 Commentary...III, 7, 687-688.

89 Commentary...III, 7, 690.

90 Ibid., 691.

91 Ibid., 692.

92 Commentary...III, 7, 694.

93 Even if in this paper I will not set out the arguments which prove that the potential intellect is not the same for all men, I would like to record that the fundamental proof we found in C. Gentes, L. II, Chapter 73 and 75; in St. Th. I, q. 76, a. 2; in the Q. tertia De Anima and in Chapters 4-5 in De Unitate Intellectus.

94 Averroes, Commentarium Magnum in Aristotelis De Anima, Librum Tertium, c. 4, 99-105, ed. Crawford, p. 386.

95 Cf. Commentary on Aristotle's De Anima, III, 7, 699.

96 Averroes, Commentarium Magnum in Arisotelis De Anima, Librum Tertium, c. 4, 67-73, ed. Crawford, p. 385.

97 Cf. Commentary on Aristotle's De Anima, III, 7, 681.

98 Cf. Ibid., 687.