Thomas Aquinas

In 2 Sent. D17, Q3, A1 (#39)

translated by rct


Aquinas, In 2 Sent. D17, Q2, A1 (text # 39)

In 2 Sent. D. 17, Q.2, A.1.

Whether there is one soul or intellect for all human beings

The issue of the relation of the intellect and the body was very challenging for thinkers of the Latin West in the Thirteenth century. This article is the first extended account of the human intellect in the corpus of Aquinas.

In Avicenna’s De Anima and Metaphysics Latin thinkers found the doctrine that the rational soul is created with the human body but stands apart from it and lives on after the death of the body because of the immateriality that its rationality entailed. For Avicenna, while the soul is per se rational, its intellect remains in potency and to be actualized requires the assistance of the separate Agent Intellect, the transcendent cause of all forms of the world, including rational forms or intelligible intentions.  The human internal powers of soul must be suitably prepared through experience and reflection upon the images of things of the world provided by the senses.  Then the rational soul’s receptive power of intellect comes to be intellectually understanding of intelligibles through the Agent Intellect.  Shared by all human beings by a process described both as an emanation and as a conjoining of the human rational soul, the Agent Intellect contains in its immaterial nature the intelligibles necessary for human intellectual understanding.  Once the soul becomes actualized in intellectual understanding in this manner, the rational soul is able more easily to receive the emanation of intelligibles or to conjoin with the Agent Intellect another time, something always required for understanding on the account of Avicenna since the rational soul has no intellectual memory of its own.

The Long Commentary on the De Anima of Aristotle by Averroes provided an account of human intellectual understanding very different from that of Avicenna. While for both Averroes and Avicenna sense perception and experience of the world are essential starting points for the development of intellect, Averroes expounded a doctrine of abstraction derived from the writings of al-Farabi who held that the content of human understanding comes from the world and not by emanation or through conjoining with the separate Agent Intellect.  Rather, the imagination holds intentions garnered from perception which are refined by the human cogitative power located in the brain and deposited into memory. The formal contents of those intentions in the memory of an individual human being are then separated from the conditions of materiality in abstraction by the Agent Intellect and transferred to a higher mode of being, the mode of intelligibles in act. These intelligibles are then received into the separate Material Intellect which constitutes an immaterial and eternal shared thesaurus of intelligibles which are the referents of human thought and intellectual understanding that make discourse and science possible for mortal human beings. For Averroes these two separate entities, the Agent Intellect and the Material Intellect, are both available to human beings acting by will and are also “in the soul” in a way not fully grasped by Aquinas in his analysis of the teachings of Averroes in this article.

In the article translated below Aquinas draws in detail from Averroes’s account and critique of the teachings of Alexander, Avempace (Ibn Bâjjah), Theophrastus, and Themistius in the Long Commentary on the De Anima and displays a comprehensive and insightful knowledge of Avicenna’s De Anima and Metaphysics. From Avicenna he accepts the account of the human possible intellect as a power of each human soul individually and as originating with the creation of the body as persisting in immaterial existence after the death of the body. He also found in Avicenna a passage on universals and particulars essential to the development of his own unique doctrine of human intellectual understanding.  However, he rejects Avicenna’s account of emanation or conjunction with a separately existing Agent Intellect as the source for the content of human intellectual understanding. In place of that Aquinas accepts Averroes’s doctrine of the abstraction of the content of understanding from the contents of perception. However, while Averroes taught in the Long Commentary on the De Anima that the Agent Intellect and the Material Intellect are separately existing and shared eternal substances, Aquinas taught that the agent intellect and the material or possible intellect are powers intrinsic to the individual human soul. For Aquinas an individual human being employing the abstractive power of the agent intellect is able to transfer intentions intelligible in potency present in phantasms or images in the brain to the mode of being of intelligibles in act and received into human understanding by the receptive power of the possible intellect. These abstracted intelligibles Aquinas calls intelligible species.  For Aquinas, then, the immaterial human rational soul created together with the body is multiplied in accord with the number of human bodies and so too are the individual powers of agent intellect and possible intellect.


Question 2.

Third it is asked whether the soul was created outside the body. Regarding this two issues are raised. First, whether there is one soul or intellect for all human beings, as a certain separate substance flowing into all bodies. Second, if there are many [souls and intellects], whether they are created in the body or outside the body.

First Article.

To the first we proceed as follows.


1. It seems that the rational soul or intellect is one in number in all human beings.2  For no form except a material form is3 multiplied in being with the division of matter.  But the intellect, as is proven in De Anima 34 is not a material form since it is not the act of a given body. This is proven from its very act because it knows all material forms. This could not be the case if it were to have one of these in its own nature or [if] it were determined to [one] on the basis of the body for which it is the act, just as the visual power would not know all colors if the pupil which is its organ were to have a determinate color.  Therefore, the intellect is not multiplied in being with the division of matter and so it remains one in all individuals of the human species who5 are divided [into individuals] only in virtue of matter.

2. Furthermore, it is impossible that the principle be more material than what it is the principle of, because the principle must be more simple. But, as is conceded by all, there are some powers6 of the rational soul which are not acts of a given body nor of an attached organ, the principle and root of which is the very essence of the soul.   Therefore, it seems that neither is the rational soul7 united to the body through its essence8 as act.9 And so it follows, as it seems, that rational souls are not distinguished10 with the division of bodies.

3. Furthermore, everything which is received in something is received in it in the mode of the recipient, not in its own mode, as is held by Dionysius and the Book of Causes.11 If, therefore, the intellect were individuated with the division of body in order to be distinct12 in diverse [individuals], it is necessary that intelligible13 forms received in [the individual intellect] also be individuated.  From that two unacceptable consequences seem to follow. One is that, since no particular is understood in act but rather [only] in potency, species14 of this sort will not be intelligible in act but will require that they be understood through other species, and so forth into infinity. The other is that the mode of receiving forms in prime matter and in the possible intellect will be the same, because in the case of both they are received as those are and not as are forms taken absolutely. Hence, just as prime matter does not know forms which it receives, so too neither [does] the possible intellect [know forms which it receives], as it seems.

4. Furthermore, for any things distinguished from one another, it is necessary that there be something diverse in the nature of each. But since the intellect is none of the things which exist before [it is actually] understanding, it seems that there cannot be15 something diverse found16 in it unless according to17 the diversity of understood18 species. Therefore, the intellects of one individual19 and another do not differ in essence but through understood species20 alone.

5. Furthermore, for all substances existing per se and immaterial, diversity in number is due to diversity of species. [This is] because, if they have their own absolute subsisting being, they cannot be distinguished essentially through something which is outside their essence on which they are spread, as bodily forms are spread on matter.  However, in the essence of these there is nothing but form, and the diversity of [form]21 brings about the diversity of species.  But it cannot be said that the intellects of  diverse human beings differ in species because human beings themselves differ in species by the diversity of their forms.  Therefore, since the rational soul is a substance subsisting in itself — otherwise it would not remain22 [in existence] after [the death of] the body — and is23 immaterial, it seems that it also does not differ in number in diverse human beings.

[Contrary arguments]

1. The case for the contrary is that it is impossible for a form one in number to belong to many individuals.  But the rational soul is the form of any given human being. For, if a human being were to have the being of a human24 from the substance of the sensitive or nutritive soul, it could not be found in a human being in reference to his first being25 which is the basis for [a human being] rising above other animals,26 and that is an unacceptable consequence. Therefore it is impossible for there to be one27 rational soul belonging to all [human beings].

2. Furthermore, it is impossible for diversity in second being to be found in those things for which there is no diversity with respect to first being. [This is] because the diversity of secondary perfections and contrariety cannot exist at once28 with the unity of first perfection because in this way contraries would exist in the same thing. But we find ultimate perfections in second being to be diverse and contrary in diverse human beings, for some of them are fools and some wise, some vicious and some virtuous.  Therefore, it is necessary that the first perfection, namely the soul, be varied in diverse [human beings] in first being.

3. Furthermore, the soul is the form and mover of the body. But in celestial bodies, according to the position of the philosophers, diverse movers are assigned to diverse bodies. Therefore it seems that diverse souls are much more surely in diverse human beings.


[A]29 I respond.  It should be said30 that there are many opinions on the part of the philosophers regarding the unity and diversity of the rational soul, when we have set aside those who assert that the intellect is one for all intellectual nature or who hold that the intellect is the same as the divine essence.31

[B] To understand these [sorts of views] it is necessary to understand that intellect is distinguished by the philosophers into three: the possible intellect,32 the agent intellect and the intellect in a positive disposition33. Possible intellect names what is in potency for receiving all understood forms,34 as vision35 is in potency for receiving all colors. Agent intellect names what makes intelligibles in potency to be [intelligibles] in act, as light which makes colors visible in potency to be visible in act. Intellect in a positive disposition or formal [intellect] is so named by them when the possible intellect has already been perfected by the intelligible species so that it is able to operate [in its own right], for no passive power36 has an operation unless perfected by the species of its object,37 as vision does not see before it has received the species of color.

[C] In light of these considerations, it should be known that nearly all the philosophers after Aristotle are in agreement that the agent intellect and the possible [intellect] differ38 in substance and that the agent intellect is39 a certain separate substance.  It is both last among the separate intelligences and related to the possible intellect as40 that by which we understand, as higher intelligences [are related] to the souls of the spheres.  But this cannot be sustained41 according to the faith.  For if, as Anselm proves,42 God did not will that the salvation of humanity come about through an angel, lest the parity in glory of human beings and angels be abolished were an angel to come to be the cause of human salvation.  Likewise, if our soul were held to depend on some intelligence or angel for a natural operation, it could not reasonably be sustained that the soul will be equal to the angel in glory.43 [This is] because the ultimate perfection of any given substance is in the completion of its operation. For this reason the philosophers mentioned hold that the ultimate happiness of human beings is to be united with the agent intellect.44 And for this reason some Catholic teachers, correcting and partially following this opinion, asserted in a probable enough way that God Himself is the agent intellect.45 [This is] because by turning to Him our soul is made blessed, which they confirm in virtue of what46 is written at John 1, 9: He was the true light, etc.

[D] Concerning the possible intellect there has likewise been great diversity among the philosophers following Aristotle. For some have said that the possible intellect is diverse in diverse [human beings], while others [have said that it] is one for all [human beings].

Among those who held it to be diverse47 in diverse [human beings] there are three opinions. 


[E] For some say that the possible intellect is nothing other than a disposition which is in human nature for receiving the impressions of the agent intellect and that this is a bodily power consequent upon the human constitution.  This was the opinion of Alexander [of Aphrodisias].  But this cannot stand up even according the intention of Aristotle who wants the possible intellect to be receptive of intelligible species. However, a disposition is not [itself] receptive but rather something which has been disposed48 [is receptive].49 But what has been disposed by this disposition is a body or a power in a body, and in that way what receives intelligible forms would be a body or a power in a body, which the Philosopher refutes.50 Furthermore, it would follow that the possible intellect would not be a power for having knowledge. For no power caused by the commixture of elements is able to know, because in this way the quality belonging to the elements would act beyond [the limits of] its species,51 which is impossible.52

[Ibn Bâjjah / Avempace]

[F] For this reason other [philosophers] said that the possible intellect is nothing but the power of imagination, insofar as it is naturally constituted such that forms which come to be53 understood in act are [already] in it.  This is the opinion of Ibn Bâjjah.  But this is also impossible because, according to the Philosopher in Book 3 of the De Anima, phantasms which are in the imaginative [power] are related to the human intellect as colors to vision.  For this reason it is necessary that the phantasms be what move the possible intellect, as color moves vision.54 The ability55 which is in the possible intellect for understanding is similar to the ability which is in the patient in potency so that it may be patient in act.56 The ability which is in the imaginative [power] is as the ability of the agent in potency so that it may be agent in act. However, it is57 impossible that the same thing be58 mover and moved, agent and patient.  Therefore, it is impossible that the imaginative power be the possible intellect.  Furthermore,59 to this extent it would follow that the power receiving the intelligibles in act which is called possible intellect would be employing a bodily organ, since the imaginative power would have a determinate organ.60

[Conclusion re. Alexander andIbn Bâjjah / Avempace]

[G] It should also be known that, according to these opinions, the possible intellect is generated with the generated body and corrupted with the corrupted body and, since there is no difference of intellect in diverse human beings except the possible [intellect]61 because the agent [intellect] is one, what62 remains of the intellect from all human beings after death is63 one in number, namely the agent intellect.  And this is heretical in the extreme because in this way reward of those deserving after death would be abolished.


[H] For this reason there is the third opinion  belonging to Avicenna, who holds the possible intellect to be diverse in diverse individuals, to be founded upon the essence of the rational soul and not to be a bodily power, to begin to exist with the body64 but not to come to an end with the body.65 Hence, with respect to the possible intellect, his opinion is what we hold according to the Catholic faith, although he errs with others concerning the agent intellect, as was said.

[Theophrastus and Themistius]

[I] Among those who hold the possible intellect to be one for all [human beings], there is a twofold opinion.66 One is that of Themistius and Theophrastus, as the Commentator [Averroes] attributes to them in his Commentary on book 3 of the De Anima. For they say that even67 the intellect in a positive disposition, which is the third, is one in all [human beings] and eternal and [that] it is, as it were, composed of the agent intellect and the possible [intellect] such that the agent intellect is as its form and, through the conjoining of the possible intellect, the agent intellect is also conjoined with us.68  [This occurs] in such a way that the agent intellect is of the substance of the theoretical intellect which also is called the intellect in a positive disposition through which we understand.  They indicate as a sign of this sort of thing that  that action of the intellect which is in our power pertains to the intellect in a positive disposition.  Therefore, since to abstract species from phantasms is in our power, it is necessary that the agent intellect belong to the intellect in a positive disposition as its form. They are led to this position because,69 since they wish70 on the basis of the demonstration of Aristotle to hold the possible intellect to be one in all [human beings] because [the possible intellect] is not a determinate particular nor a power in a body and consequently71 is eternal. And, further,72 the agent intellect is likewise eternal according to them,73 and it is impossible for the effect to be generable and corruptible if the agent and recipient is eternal. [Hence,] they asserted74 that the understood species are75 eternal. For this reason it does not happen76 that, in virtue of the fact that new intelligible species which were not before come into being, sometimes the intellect understands and sometimes it does not. Rather [this intermittent understanding happens] from the conjunction of the agent intellect with the possible [intellect], according to which77 it is conjoined to us78 through its impression.79 

[Averroes Refutation of Theophrastus and Themistius]

[J] But the Commentator also refutes80 this opinion.81 [This is] because it would follow that the forms of natural things which are understood would exist from eternity without matter and outside the soul. Due to that those species are not placed in the possible intellect as its form because the form of the possible intellect is asserted by them to be the agent intellect. Since82 the ultimate perfection of human beings is according to the intellect in a positive disposition and the first [perfection] according to possible intellect,  it would also follow that one human being would not differ from another human being, neither according to ultimate perfection nor according to first [perfection] .83 Thus, there would be one being and one operation for all human beings, which is impossible.


[K] For this reason he himself held another way, that the agent intellect as well as the possible84 [intellect] is eternal and is one85 in all [human beings], but the intelligible species are not eternal.86 He also holds that the agent intellect is not related to the possible [intellect] as its form but as a craftsman to matter and [that] the understood species abstracted from phantasms are as form of the possible intellect [and that] from the two of these there comes to be the intellect in a positive disposition.87

[Aquinas’s Refutation of Averroes]

[L] In virtue of this position he tried to escape all the impossible things which occurred for Themistius.  First because88 he shows that, if the agent intellect89 is eternal and the recipient eternal, namely the possible intellect, it is not necessary that they, namely the intelligible species, be made90 eternal.91  For the visible species has a twofold subject: one in which it has spiritual being, namely vision, and one in which it has material being, namely a colored body.  Similarly, the intelligible species also has a twofold subject: one in which it has material being, namely the very phantasms which are in the imagination,92 and according to this being those species are not eternal; and another93 [subject] in which it has immaterial being, namely the possible intellect, and according to this subject they do not have the characteristic of being generable and corruptible.94 But that seems to be no response [at all].  For, as the species of color which is in the wall and which is in the eye is not the same in number, so too95 the species which is in the imagination and in the possible intellect are not the same in number. Hence, it still remains that that species which is in the possible intellect has one subject only which is eternal and in such a way that [that species] is itself eternal only96 and what is generable and corruptible in the imagination is different in number. [This is so] unless perhaps he says97 that [the species] are eternal absolutely but not by reference to a [particular human being]98 in whom the phantasms the likenesses of which are present in the possible intellect do not exist from eternity. But nevertheless, since no phantasms are eternal, it still would follow that those species which are in the possible intellect from eternity would not have been abstracted from some phantasms, and this is contrary to the intention and words of the Philosopher.

[M] Secondly, however, he tries to show that from this position it does not follow that there is one being and one operation99 belonging to all human beings, according to which all are equally wise.100 For he says, the understood species is related to the possible intellect in some way as form to matter and because of that somehow one complete thing is made from them. [Consequently, in this the possible intellect’s] conjunction with us is through that which is formal in the mentioned conjunction, namely, through the understood species, which he says is the phantasm in us as one subject and the possible intellect itself as the other101 [subject]. Hence, since diverse phantasms are in diverse [human beings], the possible intellect is conjoined to diverse human beings with a diverse conjunction. On the basis of this human beings have diverse being.102 Also on the basis of this one knows and another is ignorant.  [This is] because [the possible intellect] is conjoined to one [human being] according to one understood species without being conjoined to another according to that [same species].  Still, there are certain understood [things]103 such as the first conceptions of the intellect by which104 it is conjoined to all human beings, [concepts] which the possible intellect is never deprived of, with [the understanding that] human beings exist from eternity, as he says. Hence, however much of the intellect that is in us he concludes is in a way corruptible and in a way incorruptible.105  [This is] because for that part in virtue of which it is multiplied, namely106 the phantasm, corruption occurs; but for the part in virtue of which it is a unity, namely on the part of the possible intellect,107 there is incorruptibility.  Hence, it follows also from this that there would remain no diversity of souls after the corruption of bodies.

[N] But this response108 is shown to be frivolous in many ways.  First, [it is frivolous] because, as was said, the species which is the form of the possible intellect is not the same in number in the phantasm as109 in the subject. Rather, it is a likeness of that. Hence, it follows that the possible intellect110 is in no way conjoined with us, and so we will not understand through it.  Second, [it is frivolous] because the conjunction of the possible intellect111 with the understood species is through an operation of intellect pertaining to second perfection. Hence, it is impossible that his first perfection and substantial being be acquired by a human being through such a conjunction. In this way, since a human being has intellect from such a conjunction as they say, a human being would not be a human being in a determinate species insofar as [the human being] has intellect.112  [This is] because113 that medium, namely the understood species, is conjoined with both of the extremes by the mode of an accident to a subject, namely with the imaginative power and with the possible intellect. [But] this is also114 contrary to [what] the Philosopher [writes] at Metaphysics 8,115 where he shows116 that the soul is united to the body without anything intermediate and also without any mediating knowledge, as Lycophron said.  That position seems to return to the one [of Lycrophon].  Third, [it is frivolous] because the operation does not come forth from the object but from potency, for the visible thing does not see but rather vision [does].  If, therefore, the intellect is conjoined with us only through the fact that the understood species in some way has a subject in us, it follows that this human being, namely Socrates, does not understand but rather that the separate intellect understands these things which [a human being] imagines.  And it is not difficult to adduce many other absurd things [from the position of Averroes].


[O] For this reason, when all the errors mentioned have been set aside, I say with Avicenna that the possible intellect begins to exist,117 but does not go out of existence with the body, that it is diverse in diverse [human beings], and that it is multiplied according to the division of matter in diverse individuals, just as other substantial forms.  And I also add that the agent intellect118 is diverse in diverse [human beings], for it does not seem likely that in the rational soul there does not exist some principle which119 can fulfill a natural operation.  That follows if there is held to be one agent intellect, be it called God or120 intelligence. Nor again do I say these two,121 the agent intellect122 and the possible [intellect], are one power named in diverse ways due to diverse operations. [This is] because [when] any given actions are reduced to contrary principles, it is impossible to reduce them to the same123 power.  On the basis of this memory is distinguished from sense because receiving species of sensibles which belongs to sense and retaining [them] which belongs to memory are reduced to contrary principles also in bodily things,124 namely dampness and dryness.  Therefore, since receiving understood species which belongs to the possible intellect and making them intelligibles in act which belongs to the agent intellect cannot [both] come together in the same thing, but receiving belongs to some thing insofar as it is in potency and making [belongs to something] insofar as it is in act, then it is impossible that the agent [intellect] and the possible [intellect] not be diverse powers.

[P] But how [the possible intellect and the agent intellect] could be rooted in one substance is difficult to see. For it does not seem that it could belong to one substance both to be in potency with respect to all intelligible forms which is the possible intellect and to be in act125 with respect to all those [intelligible forms] which is the agent intellect. [But were it] otherwise, it could not make all intelligible forms, since nothing acts except insofar as it is in act.  But, nevertheless, it should be known that it is not unacceptable that there be some two things each of which is in potency with respect to the other in diverse ways, as fire is in potency cold which belongs to water in act, and water is in potency hot,126 which is in act in fire.  Hence, [both] act and are acted upon with respect to one another.  I say that the sensible thing is related to the intellective soul similarly. For the sensible thing is intelligible in potency and has a nature distinct in act. Yet there is in the soul an intellectual light in act. But the determination of knowing with respect to this or that nature is there127 in potency, as the pupil is in potency with respect to this or that color.128  For this reason the soul has a power129 by which it makes sensible species to be intelligible [species] in act, and this power is the agent intellect. And [the soul] has a power by which it is in potency for being made in the act of determinate knowing brought about by a sensible thing's species made intelligible in act,130 and this power or potency is called possible intellect.  Upon the operations of these two powers follows all our understanding, both of principles as well as of conclusions. Hence what some say appears to be false, [namely] that the agent intellect is a disposition of principles.131

[Responses to objections:]

1. Therefore to the first it should be said that the intellect is not denied to be a material form, so that132 it might be prevented from giving being to matter as substantial form with reference to first being.  For this reason it is necessary that the multiplication of the intellect, that is, of the intellective soul, follow upon the division133 of matter which causes diverse individuals. But this is said134 with respect to its second act which is an operation. [This is] because understanding does not take place by means of a mediating bodily organ.  This occurs because an operation proceeds from the essence of the soul only through its mediating power or potency. Hence, since it has certain powers which are not acts of certain135 organs of the body, it is necessary that certain operations of the soul are not through a mediating body.

2. To the second it should be said that, whenever two things which are such that one is more powerful than another are joined and one draws the other to itself, one has some power beyond that which is subject to it. [This] is clear in regard to a flame, because fire, overcoming the vapor to which it is conjoined, has the power of illuminating and the action of the enflamed vapor can extend itself by making heat in addition to that [illuminating]. Since, therefore, in the conjunction of form to matter the form is found controlling,  the more noble and the more controlling of the matter the form will be,136 the more it will be able have a power exceeding the condition of matter.  Hence, beyond the active and passive qualities which they themselves hold on the basis of matter, certain mixed bodies have certain powers which follow upon the species, such as that the magnet attracts iron.  This is even [evidently] more found in plants, as it is clear in growth which is controlled by the power of soul, which could not be through the power of fire, as is said in De Anima 2.137 This is found still138 more to be the case in animals because sensing is in every way above the power of the elemental qualities and [is found] most perfectly in the rational soul which is the most noble of forms.  For this reason [the soul] has certain powers in which it does not share with the body at all and certain [powers] which it does share [with the body].

3. To the third it should be said that, according to Avicenna, the understood species can be considered in two ways, either with respect to the being that it has in the intellect, and in this way it has singular being, or with respect to the fact that it is a likeness of such an understood thing, to the extent that it leads to the knowledge of it, and on the basis of this part it has universality.139 [This is] because it is not a likeness of this thing insofar as it is this thing140 but rather according to the nature in which it agrees with others of its species.141  Nor is it necessary that every singular being be intelligible in potency alone, as is clear concerning separate substances. But [it is necessary] in regard to those which are individuated by matter, as are bodies. But that species is individuated142 through the individuation of the intellect and, consequently, it does not lose143 intelligible being in act. [This is] just as I understand that I understand, although my understanding is a certain singular operation. It is also evident in itself that the second unacceptable consequence does not follow, because the mode of individuation through intellect is144 other than [the mode of individuation] through prime matter.145

4. To the fourth it should be said that, as the Commentator also says in his Commentary on book 3 of the De Anima,146 it is not necessary that what is receptive of some things be deprived of any determinate nature but that it be free of the nature of what are received, as the pupil [is free] of the nature of colors.  For this reason it is necessary that the possible intellect have a determinate nature. But before the understanding which is through the reception of species it does not have in its nature any of these things which it receives from sensibles. This is because it is said that "it is none of these things which are," etc.147

5. To the fifth it should be said that, although the soul does not have matter as a  part of itself by which it exists, nevertheless it has matter in which it exists as [the matter’s] perfection.  With the division [of matter]148 [the soul] is multiplied in number and not in species. However, it is otherwise in the case of those immaterial substances which do not also have matter for which they are the forms. [This is] because in these there can be no material multiplication149 but only formal [multiplication] which brings about the diversity of species.


1 This translation is from a provisional Latin text prepared by the late P.-M. Gils, O.P., and provided by Dr. Adriano Oliva, O.P., president, Commissio Leonina. Where this text varies from that in the edition of Mandonnet (1929), the Latin of the provisional text is given together with the corresponding text in the edition of Mandonnet (M) in notes.

2 in omnibus hominibus; M: in omnibus.

3 nisi sit; M: nisi.

4 Aristotle, De Anima 3.4, 429a24-28.

5 que; M: qui.

6 potentie sunt; M: sunt potentiae.

7 anima; M: ipsa anima.

8 per essentiam suam corpori uniatur; M: corpori uniatur per essentiam suam.

9 actus; M: actus ejus.

10 anime rationales non distinguantur; M: anima rationalis non distinguatur.

11 Liber de causis, prop. 23 (24). Aquinas often cites ps.Dionysius as holding this Neoplatonic principle of participation but it is difficult to find in a precise formulation in the latter's works.

12 alius et alius; M: alius.

13 intelligibiles; M: intellectuales.

14 The Latin species can be employed denote a species of a genus in logic and it can also be used as here to denote an apprehended form. A sensible species is a form apprehended by sense, a species apprehended by imagination is a form in the imagination or a phantasm, and an intelligible species is a form apprehended by intellect.

15 possit; M: sit.

16  inveniri; M: invenire.

17 apud; M: secundum.

18 intellectarum; M: intellectivarum.

19 huius; M: istius.

20 species intellectas; M: species.

21 nisi forma, cuius diuersitas; M: diversitas formae, quae.

22 remaneret; M: maneret.

23 et sit; M: et etiam sit.

24 esse hominis; M: esse.

25 In Aristotle, De Anima 2.1, the first perfection or actuality of a thing is its substantial being or first being, while second or later perfections or being (also called “second act” and “operation” by Aquinas in the response to the first objection) are actualizations of powers or activities on the part of the thing. Cf. the terminology used in the second contrary reason below.

26 alia animalia; M: animalia.

27 esse unam; M: unam esse.

28 simul esse; M: esse simul.

29 These letters in brackets are divisions of the text corresponding to parts of our detailed commentary.

30 Responsio. Dicendum; M: Respondeo dicendum.

31 essentia divina; M: divine essentia.  Aquinas is likely referring to the view of Amalric of Bene. See J. M. H. H. Thijssen, "Master Amalric and the Amalricians: Inquisitorial Procedure and the Suppression of Heresy at the University of Paris," Speculum 71 (1996) 43-65, particularly 46-47.

32 intellectus possibilis; M: scilicet intellectus possibilis. The term "possible intellect" is based on Aristotle, De Anima 429a21-24. Cf. Avicenna, De Anima, 5.1, 81.77, Arabic 209; and 76.5-6, Arabic 206. Averroes, Commentarium Magnum in Aristotelis De Anima Libros (hereafter Commentarium Magnum), 387.

33 Intellectus in habitu corresponds to the Arabic al-'aql bi-l-malakah. This term denotes the intellect as having received actualization in knowledge and so as positively disposed with knowledge.  As Aquinas notes below, this can also be called “formal intellect” insofar as it is in a disposition of having been actualized or perfected by the reception of intelligible forms or species.  This is the human intellect subsequent to apprehension of intelligibles in act and as in a positive disposition for the reconsideration of intelligibles in act in intellectual understanding without an additional abstraction from sensible experience required. See Avicenna, De Anima, 5.1, Latin 81.78-82, Arabic, 209; and Averroes, Commentarium Magnum in Aristotelis De Anima Libros, 438.

34 Averroes writes, non habet naturam secundum hoc nisi naturam possibilitatis ad recipiendum formas intellectas materiales, Commentarium Magnum, 387, “. . . it has no nature according to this except the nature of the possibility for receiving intelligible material forms.” Taylor tr. 304.

35 visus; M: oculus.

36 virtus; M: potentia.

37 perfecta per speciem obiecti sui; M: per speciem objecti sui perfecta fuerit.

38 differant; M: differunt.

39 et est postrema; M: et postrema .

40 et habet se ita; M: et ita se habet.

41 sustineri non potest; M: non potest sustineri.

42 Anselm, Cur Deus Homo, 1.5. "Don’t you realize that man would rightly be deemed to be the servant of whatever other person would redeem him from eternal death? And if so, then man would not at all have been restored to the dignity which he would have had if he had not sinned. For man, who was meant to be the servant only of God and meant to be equal in every respect to the good angels, would become the servant of him who is not God and whom the angels do not serve." Hopkins and Richardson, tr.

43 futura sit in gloria; M: sit in gloria futura.

44 This is discussed at length by Aquinas in In 4 Sent. D. 49, Q. 2, A. 1, "Whether the blessed will see God in his essence," which is also translated in the present collection.

45 Functions of the agent intellect were attributed to God by Roger Bacon, John Peckham, Roger Marston, and some others of the Latin tradition. See the commentary for further discussion.

46 per id quod; M: per hoc quod.

47 diversum; M: diversum esse.

48 preparatum; M: praeparativa.

49 That is, a disposition is a state of something disposed in some way, not a substance or nature in its own right.

50 At De Anima 1.1, 403a10 Aristotle states that, if there is some activity of soul proper to it without body, then the soul may be separate from body. He determines just that and reasons that the reception of forms in knowledge requires that the intellect be unmixed with body at De Anima 3.4, 429a15 ff.

51 That is, beyond its nature.

52 The account of Alexander provided by Aquinas is based solely on Averroes. See Commentarium Magnum, 395-97, 430-31, 443-44.

53 fiunt; M: fuerent.

54 Aquinas’s source is Averroes’s Long Commentary on the De Anima, not Aristotle. See Averroes, Long Commentary on the De Anima, {410}; Taylor tr., pp. 316-317.

55 et aptitudo; M: unde aptitudo.

56 actu; M: in actu.

57 est autem; M: autem est quod.

58 esse; M: sit.

59 Et preterea; M: Praeterea.

60 The account of Ibn Bajjah / Avempace provided by Aquinas is based solely on Averroes. See Commentarium Magnum, 397, 404, 406, 412, 487.

61 nisi possibilis in diversis hominbus; M: in diversis hominibus nisi intellectus possibilis.

62 quod; M: sequeretur quod.

63 est; M: esset.

64 cum; M: et cum.

65 Avicenna, De Anima 5.3-4.

66 est duplex; M: duplex est.

67 quod etiam; M: quod.

68 nobiscum; M: in nobis.

69 quia, cum; M: qui.

70 velint; M: volunt.

71 per consequens; M: per consequens quod.

72 et iterum; M: et dicunt iterum quod.

73 eternus secundum eos; M: aeternus.

74 posuerunt; M: Unde posuerunt.

75 sint; M: sunt.

76 contingat; M: contingit.

77 quem; M: quod.

78 nobis; M: in nobis.

79 This account of Theophrastus and Themistius provided by Aquinas is based solely on Averroes. See Commentarium Magnum, 389-92, 406, 432-33, 448, 487.

80 reprobat; M: improbat ubi supra.

81 opinionem etiam; M: opinionem.

82 cum; M: quod cum.

83 neque primam perfectionem neque secundum ultimam; M: neque ultimam perfectionem, neque secundum primam.

84 etiam possibilis; M: possibilis.

85 est unus; M: unus.

86 Averroes, Commentarium Magnum, 406-7.

87 Averroes, Commentarium Magnum, 438-39. Aquinas misunderstands Averroes here. For discussion, see the commentary.

88 quia; M: quidem.

89 si agens intellectus; M: quod si intellectus agens.

90 facta sunt eterna; M: formae sint aeternae.

91 Averroes, Commentarium Magnum, 497-501.

92 ymaginatione; M: ymagine.

93 aliud in; M: aliud est in.

94 Averroes, Commentarium Magnum, 400-401, 500-502.

95 ita etiam non; M: ita non.

96 unum subiectum tantum quod est eternum, et ita quod ipsa sit eterna tantum; M: unum subjectum tantum.

97 dicat; M: dicatur.

98 hunc; M: eum.

99 operatio una; M: una operatio.

100 sapientes; M: facientes.

101 et aliud ipsum; M: et ad ipsum.

102 diversum esse; M: esse diversum.

103 intellecta; M: intentiones intellectae.

104 que; M: quas.

105 in corruptibile; M: est incorruptibile.

106 multiplicatur, scilicet fantasmatum; M: multiplicantur phantasmata.

107 ex parte illa unde est unitas, scilicet ex parte intellectus possibilis; M: ex parte intellectus possibilis.

108 responsio; M: ratio.

109 ut; M: et.

110 intellectus possibilis; M: intellectus.

111 intellectus possibilis; M: intellectus.

112 That is, if a human being only comes to have intellect after sense experience, image formation, and conjunction with separate intellect, then human beings are not essentially rational animals at birth and throughout early childhood and do not have the power of intellect per se but only acquire it later in life.

113 istud; M: illud.

114 est etiam; M: est.

115 Metaphysics 8, 1045a8-12.

116 ubi ostendit; M: ubi dicit.

117 esse; M: esse in corpore.

118 intellectum etiam agentem; M: etiam intellectum agentem.

119 quod; M: quo.

120 sive; M: vel.

121 duo; M: duo, scilicet.

122 intellectum; M: scilicet intellectum.

123 eandem; M: eamdem.

124  corporalibus; M: corporibus.

125 esse in actu; M: esse actu.

126 potentia calidum; M: in potentia calida.

127 est ibi; M: est.

128 huius coloris vel illius; M: hujus vel illius coloris.

129 habet virtutem: M: virtutem habet.

130 facta intelligibili in actu; M: factae intelligibilis actu.

131  Here Aquinas is following Averroes, Commentarium Magnum, 496.

132 quin; M: cum.

133 divisionem; M: ad divisionem.

134 hoc dicitur; M: dicitur immaterialis.

135 vires que non sunt actus quorundam; M: virtutes quae non sunt aliquorum.

136 erit; M: est.

137 De Anima 2.4, 416a10-19.

138 adhuc; M: hoc adhuc.

139 Here Aquinas follows Avicenna, Al-Ilâhiyyât, v. 2, 5.1, 205-6.

وهذه الصورة وإن كانت بالقياس إلى الأشخاص كلية ، فهى بالقياس إلى النفس الجزئية التى انطبعت فيها شخصية ، وهى واحدة من الصور التى فى العقل . ولأن الأنفس الشخصية كثيرة بالعدد ، قيجوز إذن أن تكون هذه الصورة الكلية كثيرة بالعدد من الجهة التى هى بها شخصي

Haec autem forma, quamvis respectu individuorum sit universalis, tamenm respectu animae singularis in qua imprimitur, est indivudua ; ipsa enim est una ex formis quae sunt in intellectu, et quia singulae animae sunt multae numero, tunc eo modo quo sunt particulares habebunt ipsae aliud intellectum universale. Latin, Van Riet, ed., v. 2, 238. “This form, although a universal in relation to individuals, is an individual in relation to the particular soul in which it is imprinted, being one of the forms of the mind. And, because individual souls are numerically many, it is possible for this universal form to be numerically many from the aspect that it is individual.” Marmura tr. of Arabic, 157.  As Van Riet notes, the Latin suffers from an omission here. Still, Aquinas is able to take from this passage the view of Avicenna that the universal is received in a plurality of individual human souls or intellects without losing its nature as an intelligible.

140 est hec res; M: haec res est.

141 ُThis is Aquinas’s own novel teaching on intelligible species according to which the intellect apprehends the natures of things in the world. The source of this is surely Avicenna, though Avicenna himself holds the very different position that the source of intelligibles in act is the Agent Intellect. The Latin Avicenna has: Cum ergo dicimus quod natura universalis habet esse in his sensibilibus, non intelligimus quod ex hoc quod est universalis, scilicet secundum hunc modum universalitatis, sed intelligimus quod natura cui accidit universalitas habet esse in istis signatis. Avicenna, Metaphysics 5.2, Latin v. 2, 244. Al-Ilâhiyyât, v.2, 211: 

فإذا قلنا: إن الطبيعة الكلية موجودة فى الأعيان فلسنا نعنى ، من حيث هى كلية بهذه فالجهة من الكلية ، بل هعنى أن الطبيعة التى تعرض لها الكلية موجودة فى الأعيان.

“If we then say that the universal nature exists in external things, we do not mean in asmuch as it is universal in this mode of universality; rather, we mean that the nature to which universality occurs exists in things external [to the mind].” Marmura tr. of Arabic, 161.

142 illa individuatur; M: istae individuantur.

143 perdit; M: perdunt.

144 modus est individuationis per intellectum; M: individuationis modus est per intellectum.

145 Note that Aquinas has changed the terms of the debate here. For Averroes the issue under consideration is the intellectual understanding of intelligibles  in act which  makes universal knowledge possible. Arguing on the basis of the intellectual understanding had by an immaterial intelligence or separate substance as pure form for whom intellectual understanding of its own essence is necessarily immediate (insofar as it is per se intelligible and intelligent), Aquinas asserts that a human being’s awareness and understanding of one’s own activity of understanding  is of the same sort. However, that does not follow due to equivocation, as Aquinas later makes clear in a more sophisticated discussion of the issue in his De Veritate q.10, a.8. There he distinguishes under the influence of Augustine the immediate self-awareness of its essence and operations by the human soul from the understanding or knowledge gained through apprehension of intelligibles in act for knowledge of universals. Here in the Commentary on the Sentences Aquinas argues from the notion of individual separate intelligences having immediate self-understanding that the term ‘understanding’ need not be confined to intellectual understanding of the  quiddities of things as universals but can also suitably be used of individual acts of awareness. If that use is not equivocal but univocal, then Aquinas can argue there are individual acts of intellectual understanding that take place in individual human intellects. This would then refute the notion that there can be only one intellect (agent intellect, possible intellect, or both) for all human beings.

146 Averroes, Commentarium Magnum, 410. Also see 385-86.

147 Aristotle, De Anima, 3.4, 429a21-24.

148 ad cuius divisionem; M: ad ejus enim divisionem.

149 multiplicatio materialis; M: materialis multiplicatio.