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The translator wishes to thank Dr. James H. Robb, Chairman of the Editorial Board, for his many excellent suggestions on the text of the translation. Thanks are due also to Dr. Ida Critelli, Dr. Thomas Anderson, and Dr. Peter Maxwell, who as graduate assistants, provided some valuable help in the work on the notes. Introduction "Angel of the Schools though he may be, St. Thomas does not speak from some abstract philosophical heaven. It is to the thirteenth century that St. Thomas gives voice. A polemical work, as the title suggests, it was written to answer a difficult problem of St.

Thomas' time; it confronted a challenge that Greek and Arabian philosophy had offered to Christian thinkers. After observing that in nature as a whole we find two factors, a potential factor and a productive or active factor, Aristotle says that "these distinct elements must likewise be found within the soul. Mind is not at one time knowing and at another not.

When mind is set free from its present conditions it appears as just what it is and nothing more: this alone is immortal and eternal we do not, however, remember its former activity because while mind in this sense is impassible, mind as passive is destructible , and without it nothing thinks.

That Aristotle was here distinguishing between an active intellect that makes things actually intelligible and a passive intellect that receives these intelligibles was clear, but beyond this point his meaning was not altogether clear to his readers. What did he mean by saying that mind is "separable, impassible, unmixed," "immortal and eternal"?

Could an intellect with these characteristics be a power of the human soul, or was Aristotle implying that intellect is a substance that is separate and distinct from man, and one for all men? Among the Greek commentators, Theophrastus ca. Pegis, Saint Thomas and the Greeks, p. Milwaukee: Marquette University Press, Smith in Basic Works of Aristotle, ed. New York: Random House, Avicenna situated his doctrine of the agent intellect within the context of his theory of emanation.

At the summit of his universe is a Necessary Being, who is one, incorporeal, and the source of all other beings. This Necessary Being reflects upon itself, thereby necessarily giving rise to the first effect, a pure intelligence. This effect must be one, for from one simple thing, only one can proceed. When the First Intelligence thinks of itself as necessary by the First Being, it gives rise to the soul of the outermost celestial sphere; when it thinks of itself as possible in itself it gives rise to the body of this same sphere.

Then, in a similar way, the Second Intelligence gives rise to a Third Intelligence and to the soul and body of the second sphere. This emanation of intelligences and spheres is halted only with the production of the sphere of the moon and the tenth or last intelligence, which is the agent intellect or Agent Intelligence. But these souls can receive the species only after considering and comparing the images that have come from the senses.

These movements prepare the soul for the "abstraction," that is, the emanation of intelligible forms. For intellectual knowledge, the soul must again be united with the separate Agent Intelligence. Verbeke Louvain: Publications Universitaires de Louvain, , pp. In the transcription by G. Klubertanz, S. Louis University, , pp.

It cannot be ''numbered to the number of individuals" but must be wholly separate from matter to insure its power for knowing universals. Man's highest powers, the cogitative power, imagination, and memory, have the task of preparing the sensory data that the separate intellect will utilize. So important is this highest task that man by himself can perform, that Averroes sometimes dignifies the cogitative power with the name of intellect: not possible intellect, however, but passible intellect, to designate its generable and corruptible nature.

The separate possible intellect can then be actuated and become the subject in which knowledge exists. Men's phantasms are, for Averroes, the subject in relation to which knowledge is true. Averroes is less concerned with explaining just how this can be, than with keeping the intellect free of matter to preserve its function of knowing. He had no awareness of a spiritual intellective soul that could be the form of the body without being immersed in matter. These views of the intellect by Greek and Arabian thinkers became known to Christians of western Europe.

During the twelfth and thirteenth centuries the works of Aristotle, accompanied by the commentaries of Arabian thinkers, came into Europe in Latin translation. As a result of the work of translation done at the court of Frederick II of Sicily and the School of Archbishop Raymond of Toledo, Spain, a new world of literature was introduced to Christian thinkers. Although Aristotle had previously been known and admired for his logical works, Christians now had access to other works of "The Philosopher," including his work on the soul.

Crawford Cambridge, Mass. One reaction to the influx of the new literature is seen in the condemnations of and In the Provincial Council of Paris prohibited the teaching of Aristotle's works on natural philosophy or their commentaries. Some Christians were to accept in a modified form, Avicenna's doctrine of a separate agent intellect.

Albert wrote, in , On the Unity of the Intellect against Averroes. Directing his treatise not against Averroes alone, but against Arabian thought, he presented thirty arguments for the unity of the human intellect and thirty-six arguments against it. He stopped with this majority of six in favor of his own position only, he said, because of lack of time. As more Christian thinkers read Aristotle and Averroes in Latin translation, the Philosopher was seen through the works of his Commentator.

The result, for some, was that Philosophy was identified with the Commentator's positions. Philosophy itself, for these Latin Averroists, seemed to say that the possible intellect is a separate substance and one for all men. As philosophers, the Averroists held that this was the conclusion of human reason, but as Christians they refrained from saying that this doctrine was true. Without explicitly teaching a theory of "double truth," such a leading Averroist as Siger of Brabant nevertheless conveyed the impression of a conflict between faith and reason.

The Averroists' views on the intellect and their implications for Christians were censured in and in the condemnations of Etienne Tempier, Bishop of Paris. Bonaventure and of Giles of Rome ca. Denifle and A. Chatelain eds. Spettman ed. IX Paris: Vives, , pp. Thomas' treatise against the Averroists.

The Authenticity, Date, and Title of St. Thomas Aquinas. It is found in manuscripts explicitly attributed to St. Thomas in the thirteenth century. It is listed in almost all the older catalogues of St. Thomas' writings. No serious doubt has been raised about the authenticity of St. Thomas' treatise. The De Unitate Intellectus is one of the later works of St. After his first period of teaching as a Master at Paris and after his teaching at the papal curia in Italy , St.

Thomas returned to Paris. The De Unitate Intellectus belongs to his second period of teaching at Paris The date has been more exactly stated as the year IX Paris: Vives, Giles of Rome, Errores Philosophorum, c. Koch, tr.

Averroes and the Agent Intellect

Bocca Rome, Mandonnet, Des Ecrits Authentiques de S. Grabmann, Die Werke des hl. Synave, "Le catalogue officiel des oeuvres de s. Eschmann, "A Catalogue of St. Thomas' Works," in E. Gilson, The Christian Philosophy of St. Thomas, Introduction to K. Foster and S. Humphries tr. Salman, "Compte Rendu: F. Commentary on the Sentences ca. It was roughly contemporaneous with another anti-Averroistic work, the De Aeternitate Mundi contra Murmurantes ca.

It was perhaps followed by the writing of some of the Commentary on Aristotle's De Anima ca. But the title most often found is Treatise concerning the Unity of the Intellect against the Averroists. Some scribes, thinking that this title needed a clarification, added an explanatory phrase: "concerning the unity of the intellect against the Averroists, or rather against the unity of the intellect which the Averroists held. Thomas is opposing. Attempts have been made to determine more exactly what particular Averroist St.

Thomas may have had in mind, for example in , where he seems to cite a definite individual. Mandonnet thinks that St. Thomas was opposing Siger of Brabant, who was the leader of the Averroists at Paris at that time, and two of the older manuscripts assert this. One is entitled: The Treatise of Brother Thomas against Master Siger concerning the Unity of the Intellect; and the other states: "Thomas wrote this against Siger of Brabant and many others, predominant in philosophy at Paris in the year of our Lord, On the dates of St.

Thomas' works, see Grabmann, op. Mandonnet and J. Walz, "Saint Thomas d'Aquin. See p. Thomas attacks in the body of his treatise. Yet this does not mean that St. Thomas did not oppose Master Siger. The Chronological Relation of St. His unorthodox views were included in both of Bishop Tempier's condemnations: December 10, and March 7, Thomas attacked,24 but later research has shown that it was composed after St.

The De Unitate Intellectus, scholars have said, does not seem to reflect the De Anima Intellectiva; there is no point by point refutation as one might expect in a work of this kind. Thomas' treatise, the question, "What work of Siger was St. Thomas opposing? Perhaps it was a work, no longer extant, that is cited in the Quodlibeta of John of Baconthorp, a fourteenth century Carmelite. Chossat points out that the Siger cited in Baconthorp thought, for example, that the intellect is united with man only by means of phantasms, and that, according to Aristotle, only the passive intellect or imaginative power footnote continued from previous page entes, anno D.

This Siger also implied that the intellect is a mover just as, in Averroes' context, the intelligence that moves the heavens is, without being a form, a principle of operation for the heavens. Thomas refutes. He adds that without a knowledge of Baconthorp's Siger, one might think the first part of the De Unitate captious, entangled, and insistent beyond reason on points which seem evident, but with such a knowledge one sees St. Thomas' treatise as well ordered and adapted to refuting the errors of Siger. Thomas' attack is the Quaestiones in Tertium de Anima. This work, which is dated before and is averroistic in content, is also attributed to Siger.

He observes, however, that one can find in the De Unitate echoes of some of the texts from these questions, notably Siger's discussion on whether the separated soul can suffer from fire. This does not mean that they were necessarily true publications of Siger. They might have existed only in the form of reportationes of students. Van Steenberghen sees evidence of this in the Quaestiones in Tertium de Anima. Thomas' sources were students' notes of Siger's oral teaching, this would explain, says Van Steenberghen, the double fact that St.

Thomas seems to use and refute a text and yet reproaches his opponent for not rendering his teaching public and controllable. John of Baconthorp, Quodlibeta I, 1 Venice, , fol. See St. Thomas, De Unitate Intellectus, , esp. See Quaestiones in Tertium de Anima, q. Thomas, De Unitate Intellectus, The latter part of Van Steenberghen's comment is a reference to De Un.

In the final paragraph of the De Unitate St. Thomas issues a challenge. Speaking of his opponent he says: ". Did Siger ever answer St. Thomas' De Unitate? We have noted that the De Anima Intellectiva was written after the De Unitate and reveals a knowledge of some of the content of St. Sylvester of Ferrare, O. Augustino Nifo ca. Nifo's comments on the contents of the De Intellectu strongly suggest that it is different from the De Anima Intellectiva and that it manifests a particular interest in the possible intellect.

It may imply, too, that the oral teaching of the Averroists was imparted to small groups in private places. Keeler notes, op. Thomas, XIV, p. Sylvester speaks of Rugerius, but this is regarded as an evident corruption of Sigerius. See Van Steenberghen, Siger dans l'Historie. Antonio Milani, , pp. Thomas had left Paris for Italy. This contrast with the views of the Siger of Baconthorp and the Siger of the Quaestiones in Tertium de Anima, does not mean that he now accepted a Thomistic position, since this form that he speaks of in the De Anima Intellectiva is a forma intrinsecus operans, a form intrinsically united to the body for operation.

It operates within man in order to know, although it is separate in its being from the body. Relying on these texts, Van Steenberghen 38 Nardi, op. On the date of the De Intellectu, see da Palma, op. Van Steenberghen, Siger dans l'Histoire. It should be noted that Jean of Jandun d. Although the name is given as "Remigius," it is clearly Siger who is intended; Nardi, op. See S. Maurer, op. Van Steenberghen, Siger dans l'Historie. Thomas' treatise cannot be stated in a definitive way. Tentatively, however, the sequence of works perhaps could be summarized thus: 1 The Siger mentioned by Baconthorp 2 Siger's Quaestiones in Tertium de Anima in the form of reportationes 3 St.

We do not know whether St. Thomas ever received that work or whether he saw any part of the De Anima Intellectiva. Chossat conjectures that perhaps it may have seemed futile to Thomas to continue the dialogue since the reworded version of Siger's position offered nothing basically new, or perhaps death may have come March 7, before St. Thomas had time to answer. The Content and Structure of St. Thomas' Treatise St. Thomas begins the De Unitate Intellectus contra Averroistas with a statement of his purpose and his method of procedure in this work. Although he has written before against Averroes' erroneous view on the intellect, he intends to write against it again and clearly refute it.

He is concerned about the spread of this error and the boldness of those who expound it.


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He distinguishes two aspects of the error: 1 that the possible intellect is a substance that is separate in its being from the body and not united to it as its form; and 2 that this possible intellect is one for all men. Van Steenberghen, p. Maurer, ''The State of.

His method of procedure will not be to show that the error is contrary to the teachings of the Christian Faith, for this is quite evident. He intends instead to show that the error is against the principles of philosophy and against the words of those very Peripatetics to whom these men appeal.

He will therefore challenge them on their own ground by using philosophical arguments and the method of textual analysis. The two aspects of Averroes' error provide the two main parts of the body of the treatise, with the first three chapters pertaining to the first aspect of the error, and the last two chapters pertaining to its second aspect.

The division into five chapters is found in the older editions and in manuscripts and, in Keeler's opinion, was probably made by St. Thomas himself. The possible intellect is not a substance that is separate in its being. The possible intellect is not one in all men. This is established Chapter IV by arguments, especially from Aristotle, Chapter V by refutations of the adversaries' arguments. In dealing with the first aspect of Averroes' error, namely, that the intellect is a substance separate in its being from the body, St. Thomas begins with an analysis of Aristotle's texts Chapter I, sections in order to show that this is not the Philosopher's view.

So thorough and detailed is the analysis that St. Thomas gives the impression of not omitting any text to which his opponents appealed in support of their views.

Breadcrumb

For them the Philosopher's way of defining the soul implied that the intellective faculty or intellect was excluded from his definitions. For St. Thomas, Aristotle's definitions of soul included the intellect, and the reference to intellect as "separate" meant not separate from the body, but different from sense powers in that it has no corporeal organ. Thomas answers , is one that especially reflects the Averroists' view.

Assuming that there are 45 Keeler, Introduction, op. Keeler refers the reader to the analytical tables worked out by C. Ottaviano, Saggio Contra la Dott. Lanciano, , pp. See also the analysis of Van Steenberghen, Siger dans l'Histoire. On this supposition, would it not be immersed in matter and so be unable to know? Or, differently phrased: How can the human soul be so intimately united with the body as to be its substantial form and yet have one of its powers so separate from the body that that power can have intellectual knowledge?

The answer lay, St. Thomas thought, in acknowledging another kind of form of matter. Although some forms of matter neither act by themselves nor exist by themselves, but exist only through the composite, there are other forms of matter that do act by themselves and hence are subsistent. They do not exist through the composite, but the composite exists through them. Not being immersed in matter, they can have acts that are not acts of a corporeal organ. At the end of the first chapter St.

Thomas says 50 : ''. Thomas wishes to show that the Greek and Arabian Peripatetics to whom his opponents appeal, also regarded the possible intellect as a part of the human soul and not as a separate substance. In presenting the views of two of the Greeks, St. Thomas has a special advantage over his adversaries.

He cites some texts in which Themistius states his own view and that of Theophrastus, and thereby tries to establish that for both, the intellect is a power of the human soul. Thomas states that he has referred to the Greeks and the Arabs not because he wishes to rely upon their authority; rather he wishes to show his opponents that not only the Latin philosophers but also the Greeks and the Arabs whom they hold in esteem, regarded the intellect as a power of the soul.

He wonders from which Peripatetics they have. Thomas gives philosophical arguments to show that the intellect is a power of the soul which is the form of the body. His principal argument starts from the evident fact that this individual man knows Hic homo singularis intelligit. They said that the intellect is united to the individual as a mover and therefore the man knows. But what is the individual man in this context? Thomas asks. Is he intellect alone motor , or a body animated by a vegetative and sensitive soul motum , or the composite resulting from the union of mover and moved?

Thomas concludes that one cannot say that the intellect is united to man as a mover, and even if it were, this would not explain that this individual man knows. Thomas presents, though more briefly, two other arguments to show that the intellect cannot be a substance that is separate in its being from the body. Since the distinguishing act of man's species is the act of understanding, the principle of this act, that is the intellective soul, must be united to man's body as its form.

But then man would not be the master of his acts, and the basis of moral philosophy would be destroyed. Thomas concludes this chapter by refuting objections of the Averroists. Thomas proceeds in Chapter IV to consider the second aspect of the error: that the intellect is one for all men. He remarks that although something can perhaps be said for the unity of the agent intellect, to say that the possible intellect is one for all men involves absurd consequences.

Among the consequences that he discusses is that there would then be but one knowing being. This view then fails to account for the obvious diversity of acts of knowing and willing. Besides, it is contrary to the teachings of Aristotle ; even if it were not, no matter how the relation of the one intellect to our phantasms is explained in Averroes' context, Averroes' doctrine cannot account for the fact that man knows.

Thomas tries to understand why the Averroists are opposed to a doctrine of the plurality of possible intellects. He states and answers several objections. The Averroists argue, for example, that because the thing understood is one, therefore the intellect must be one. Thomas shows that they prove too much, for they should conclude then not only that there is one intellect for all men, but that there is only one intellect in the whole universe, thus denying plurality to separate substances. Thomas tries to probe to the source of their difficulty by asking what they mean by "the thing understood.

The latter is really their meaning, St. Thomas shows, and their trouble arises from not seeing a distinction between the two meanings. Thomas tries to show his opponents how one existent thing can be known by many persons by means of the species which each one's intellect has. Thomas again calls attention to philosophers' actual texts. He stresses that the Greeks and the Arabs to whom his opponents mistakenly appeal in support of their error, have all upheld a plurality of possible intellects.

Thomas addresses a more direct and theological criticism to his opponents and to one unnamed Averroist in particular. What disturbs St. Thomas even more than their error concerning one intellect, is the irreverent attitude they have towards the Christian Faith. To say, as one Averroist does: "I necessarily conclude through reason that the intellect is one in number; but I firmly hold the opposite through faith," is to imply that faith is concerned with something false and impossible. To so oppose reason and faith, and to dispute about matters of faith that do not pertain to philosophy, is unbecoming to Christians.

In the last section of the De Unitate St. Thomas restates from 2 the method he has used to refute the Averroists' error; he has appealed, in the body of his treatise, not to the teachings of faith but to the arguments and words of the philosophers themselves. Thomas concludes his treatise by issuing a challenge in unusually strong and vigorous language: ". If there be anyone boasting of his knowledge, falsely so-called, who wishes to say something against what we have written here, let him not speak in corners, nor in the presence. Foreword: Statement of Purpose and Method: This is not the view of Aristotle: Chapter I: 1.

De Anima of Aristotle excludes an Averroistic interpretation: a. Analysis of Aristotle's definitions of soul: b. Interpretation of words at beginning of III de Anima: c. Analysis of Aristotle's references to Empedocles and Anaxagoras: 2. Interpretation of a text from Physics: 3. Refutation of objections: B. This is not the view of the Peripatetics: Chapter II: 1. Greeks: 2. Arabs: 3. Conclusion: 59 C. This is not the view of sound philosophy: Chapter III: 1. Arguments by which one can establish that the intellective soul is the substantial form of man: a.

Principal argument: 1 Statement of argument proceeding from this undeniable fact: Hic homo singularis intelligit: 2 Averroes' view fails to explain this fact: Argument proceeding from a consideration of man as a member of the human species: 80 c. Argument based on requirements of moral order: 2. Refutation of objections proposed by Averroists: III.

Is the Intellect One for all Men? The possible intellect is not one for all men: Chapter IV: 1. Unicity of the intellect involves absurd consequences: Unicity of the intellect is incompatible with Aristotle's doctrine: 3. No matter how the relation of the intellect to our phantasms is understood, the doctrine of one possible intellect for all men cannot explain human knowledge: B.

Objections against the plurality of possible intellects, and refutations of these objections: Chapter V: C. Thomas' time, it was not just an occasional or ephemeral work. It touches upon some very basic and vital questions which surpass in their reach, the limits of a thirteenth century polemic. For example: 1 What is the soul? Thomas' treatment of these and other questions in the De Unitate is notable for its clarity of expression and the depth of his philosophical insight. Father Leo W. Thomas' text. It includes Keeler's section numbers to facilitate reference to the text, and Keeler's titles for chapters and parts of chapters.

Although using Keeler's notes as a guide, it does not reproduce them exactly. The bibliography which follows in Section F, is intended to direct the reader to works that will aid in the understanding of the background and content of the De Unitate, and of some of the main problems with which the treatise is concerned.

Selected Bibliography Aristotle, De Anima, tr. Smith, in The Basic Works of Aristotle, ed. Cambridge, Mass. Chossat, M. Gilson, E. The Christian Philosophy of St. Elements of Christian Philosophy, Chapters New York: Scribner's, Keeler, L. Thomas' 'De unitate intellectus,'" Gregorianum 17 , Rome: Gregorian University, , , Mandonnet, P.

Pegis, A. Thomas and the Unity of Man," pp. Milwaukee: Bruce, Robb, J. Thomas Aquinas, St. Tractatus de Unitate Intellectus contra Averroistas, critical edition by L. The Soul: A Translation of St. Thomas Aquinas' De Anima, by J. Louis: Herder, Aristotle's De Anima with the Commentary of St. Thomas Aquinas, tr. New Haven: Yale University Press, On Spiritual Creatures, tr. Fitzpatrick and J. New York: Doubleday Image Books, Summa Theologiae I, pp. Thomas Aquinas, I, tr. Van Steenberghen, F. Aristotle in the West, tr.

Louvain: Nauwelaerts, Verbeke, G. Louvain: Publications Universitaires de Louvain, Foreword1 1. Just as all men naturally desire to know the truth,2 so there is inherent in men a natural desire to avoid errors, and refute them when they are able to do so. Now among other errors, the error that seems especially inappropriate is the one concerning that very intellect through which we are meant by nature to avoid errors and know the truth. For a long time now there has been spreading among many people an error concerning the intellect, arising from the words of Averroes. The numbers preceded by " " are Keeler's section numbers.

In his Commentarium Magnum in Aristotelis de Anima Libros Averroes cites Alexander's views, borrows his term, but differs from him on the nature of the material or possible intellect; see in the critical edition of The Mediaeval Academy of America, Cambridge, Mass. It is not now our intention to show that the above-mentioned position is erroneous in this, that it is opposed to the truth of the Christian Faith.

For this can easily enough become evident to everyone. For if we deny to men a diversity of the intellect, which alone among the parts of the soul seems to be incorruptible and immortal, it follows that after death nothing of the souls of men would remain except that single substance of intellect; and so the recompense of rewards and punishments and also their diversity would be destroyed. However, we intend to show that the above-mentioned position is no less against the principles of philosophy than against the teachings of Faith.

And because, so they say, the words of the Latins on this subject have no savor for some persons, but these men say that they follow the words of the Peripatetics, whose books on this subject they have never seen, except those of Aristotle who was the founder of the Peripatetic Sect;8 we shall show first that the above-mentioned position is entirely opposed to his words and meaning. Thomas accuses the Averroists of knowing authorities only as they were quoted by Averroes, who himself ''was not so much a Peripatetic as a perverter of Peripatetic philosophy. Chapter I. Aristotle did not teach that the possible intellect is a substance separate in its being from the body.

The definition of the soul that Aristole gives, belongs also to the intellective soul. The first definition of the soul that Aristotle sets down in Book II of the De Anima, saying that "the soul is the first act of a physical organic body,"1 should be accepted. And lest perhaps someone might say that this definition does not apply to every soul2 because of the fact that Aristotle had previously qualified his treatment by saying: "If it is necessary to say that there is something common to every soul,"3 which they interpret as meaning that this could not be, the words of his that follow should be accepted.

For he says: "It has been stated in a universal way what the soul is. For a substance is what it is by definition; now this is the essence of this body,''4 that is, the substantial form of a physical organic body. And lest perhaps it be said that the intellective part is excluded from this universal statement, this is answered by what he says afterwards: "It is indeed clear therefore that the soul is not separable from the body, or that certain of the soul's parts are [not separable], if it naturally has parts, for it is the act of the certain parts themselves. But truly nothing prevents certain parts [from being separable] since they are not the acts of any body.

From this it is clearly shown concerning that soul which Aristotle had defined above in a universal way as the act of the body, that it has some parts which are acts of some parts of the body, but also some which are acts of no body. For it is one thing for the soul to be the act of the body and another for part of it to be the act of the body, as will be shown later. Thomas, Comm. For the soul is also said to be that by which we first live and understand.

But it becomes still clearer from what follows that the intellect is also included under this general definition. For although he has sufficiently proved that the soul is the act of the body since when the soul is separate from it, the body is not actually living ,8 yet something can be said to be actually such by the presence of something, not only if it is a form but also if it is a mover just as what is combustible is actually burned by the presence of something burning, and whatever is movable is actually moved by the presence of something moving.

For this reason someone could come to doubt whether a body is actually living by the presence of a soul in the way in which what is movable is actually moved by the presence of a mover, or in the way in which matter is in act by the presence of form. And especially because Plato held that the soul is not united to the body as its form but rather as its mover and ruler, as is clear through Plotinus and Gregory of Nyssa;9 I mention these because they were not Latins but Greeks.

On the unity of the intellect against the Averroists (De unitate intellectus contra Averroistas)

This doubt therefore is what the Philosopher is hinting at when he adds to what he has said: ''But further, it is unclear whether the soul is the act of the body in the way that a sailor is of a ship. Then because after what he had said, this doubt still remained, he concludes: "The soul is thus indeed defined and described in a general way,"11 because he had not yet clearly demonstrated the truth. To remove this doubt therefore, he next proceeds to show that which is more certain both in itself and in knowledge, through those things that are less certain in themselves but more certain to us, that is, through the effects of the soul which are the acts of the soul.

Then he at once distinguishes the works of the soul, saying that "the animate is distinguished from the inanimate inasmuch as it is living," and that there are many things which pertain to life, namely, "intellect, sense, motion and position according to place, and the motion of nourishment and growth" so that "in whatever being any of these is found, that thing is said to live.

Thomas seems to be referring to passages that he cites in 76, See notes to these sections. And Plato held that there are diverse souls in man, according to which distinct vital operations belong to him. And he adds that "in some cases this does not seem difficult, but some cases raise a question. But he shows which points he considers questionable when he adds that "nothing is as yet evident concerning the intellect and perceiving power. And although he says this is not yet clear, yet he shows what is apparent on this point at first glance when he adds: "But it seems to be another genus of soul.

And because the corruptible and eternal do not seem able to come together into one substance, it seems that of the parts of the soul, it belongs to this part alone namely the intellect to be separated not indeed from the body, as the Commentator wrongly explains,22 but from the other 15 Plato, Timaeus 89EA, 69CA, in B. Jowett tr. Averroes cites Plato in In de Anima I, comm. And that it must be understood in this way is evident from the following: "As for the remaining parts of the soul, it is clear from what has been said that they are not separable,"23 that is, either with regard to subject or to location.

For this was the question put above, and this is what was proved from what was said above. And that it is not to be understood to concern separability from the body, but separability of the powers from one another, is clear from what follows: "That they are different in definition," that is different from one another, ''is clear. For the sensitive is different from the opinionative. For the question above was whether one part of the soul is distinct from another part only by reason, or also separate in location. Having here dismissed that question with regard to the intellect, about which he settles nothing here, he says concerning the other parts of the soul that clearly they are not separable, that is in location, but they are distinct by reason.

With this point secured, that the soul is specified by the vegetative, sensitive, intellective, and motive [powers], he wishes to show next that as regards all those parts, the soul is united to the body not as a sailor to a ship, but as form. And thus, what the common meaning of soul is, which had been treated above only in a general way, will have been established. And so it is clear that knowledge is the form of the soul as health is of the body.

From this he develops his argument as follows: "The soul is the first principle by which we live this he says because of the vegetative power , by which we sense because of the sensitive power , by which we are moved because of the motive power , and by which we understand because of the intellective power ; and he concludes: "Wherefore the soul will undoubtedly be a certain definable form and 23 Aristotle, De Anima II, 2, b See also 7 of De Unitate Intellectus and Comm.

See also St. Therefore what Aristotle meant was that that by which we understand is the form of a physical body. But lest anyone say that that by which we understand does not mean here the possible intellect, but something different, clearly this is excluded by what Aristotle says in III De Anima, when speaking of the possible intellect: "I speak moreover of the intellect by which the soul thinks and understands.

Aristotle states that the intellect is a power of the soul which is the form of the body. But before we take up the words of Aristotle which are in III De Anima, we should dwell still further on his words in II De Anima, so that from a comparison of his words with each other, it may be clear what his teaching on the soul was.

For when he had defined the soul in general, he begins to distinguish its powers; and he says that "the powers of the soul are vegetative, sensitive, appetitive, locomotive, intellective. And that he had said that the intellect is a power of this soul and that the definition of the soul stated above is common to all the parts mentioned before is evident from his conclusion: "Therefore it is clear, since there will undoubtedly be one definition of soul in the same way as there is one of figure; for the figure is not there as something over and beyond the triangle and the others that follow from it; nor is the soul here as something over and beyond the parts mentioned.

Aristotle makes no further mention of the intellect in Book II, except his later remark that "the last and the least he says is reason27Ibid. And see St. But because there is a great difference as regards the mode of operation, between the intellect and the imagination, he adds that "the notion of the speculative intellect is different. And lest anyone should say, as Averroes wrongly explains,34 that the reason Aristotle says that the notion of the speculative intellect is different is that the intellect is neither the soul nor a part of the soul, he immediately excludes this at the beginning of Book III,35 where he takes up again the treatment of the intellect.

For he says: "As for the part of the soul by which the soul knows and understands. Moreover, the wonderful carefulness and order in Aristotle's procedure must be considered. Now he had previously left two things unsettled about the intellect. First, whether the intellect is separated from the other parts of the soul only by reason, or also in location; this he had left unsettled when he said: "Nothing is as yet evident concerning the intellect and perceiving power. Thomas follows the division of books as they are in the Greek copies, in this work because he is concerned with Averroes and the Averroists , he uses the division which the Arabs used, according to which Book III begins with Chapter 4 of Book III of the Greek a See De Unitate Intellectus, 7.

Secondly, he had left unsettled the difference between the intellect and the other parts of the soul, when he said afterwards: "But the notion of the speculative intellect is different. The very manner of speaking makes this sufficiently clear. For he says that it should be considered what the intellect's difference from the other parts of the soul is, whether it is separable from them in size or location, that is in subject, or not separable in that way but only by reason. The intellect is compared with sense.

Empedocles and Anaxagoras. But because in certain words that follow, the Averroists wished to understand Aristotle's meaning to have been that the intellect is not the soul which is the act of the body, or part of such a soul;46 for that reason his next words must be considered even more attentively. Immediately therefore after the question proposed about the difference between the intellect and sense, he asks47 in what respect intellect is like sense and in what respect it is different from it. For he had pre41Ibid.

See De Un. Siger of Brabant is reported by John Baconthorp to have said that if by intellect we mean the immaterial possible intellect that we call the intellective soul in us, then the Philosopher does not prove that the intellective soul is the form of man. John of Baconthorp, Quodlibeta Venice, , fol. See M. Chossat, "St. This therefore is what Aristotle is trying to point out when he says: "If therefore understanding is like sensing, either it will surely suffer from an intelligible object," inasmuch as intellect would be injured by an excessively intense intelligible object as sense by an excessively intense sensible, "or something of this kind, yet different.

To this question therefore he immediately answers; and he concludes not from what precedes but from what follows, although what follows is clear from what precedes that this part of the soul "must be impassible"50 so that it is not injured, as is sense. It has however another kind of passivity, inasmuch as understanding is said in a general way to suffer. In this respect, therefore, it differs from sense. But next he shows how it is like sense, because, namely, a part of this kind must be "receptive of an intelligible species," and be "in potency" to a species of this kind, and "not be this'' in act according to its own nature;51 just as it was previously said about sense, that it is in potency to sensible things, and not in act.

But this led to the exclusion of the opinion of Empedocles and other ancient thinkers who stated that the knower is of the nature of the thing known, for example that we know earth inasmuch as we are earth, and water inasmuch as we are water. But there is a difference between sense and intellect, because a sense is not able to know all things, but sight can know only colors; hearing, only sounds; and so for the rest; whereas the intellect is able to know all things without such limitations. Now the ancient philosophers used to say, since they were of the opinion that the knower must have the nature of the thing known, that the soul, in order to know all things, must be a mixture of the principles of all things.

But because Aristotle already proved through a comparison with sense, that the intellect is not actually but only potentially that which it knows, he concluded to the contrary that "because the intellect knows all things, 48 Aristotle, De Anima II, 11, b 30 - al; a 25 -b3. Diels, Die Fragmente der Vorsokratiker, fr. And to show this, he brings in the testimony of Anaxagoras,56 who was not, however, speaking about this same intellect, but about the intellect that moves all things. Therefore just as Anaxagoras said that that intellect was unmixed, so that it might rule by moving and separating out, so we can say about the human intellect that it must be unmixed so that it may know all things; and this he proves thereafter and so the following line is found in the Greek: "That which appears within will hinder and obstruct what is without.

Likewise, if the nature of the things which the intellect knows, for example, earth or water, what is hot or cold, or anything of this kind, were intrinsic to the intellect, that nature within the intellect would hinder and in some way prevent the intellect from knowing other things. Because therefore it knows all things, he concludes59 that "it cannot itself have any nature" which is determined by the sensible natures that it knows; "but it has this nature alone, that it is possible," that is, in potency to those things that it knows, so far as its own nature is concerned; but it becomes those things in act during the time in which it actually knows them; as the sense in act becomes the sensible in act, as he had said above in Book II.

And because he had mentioned the statement of Anaxagoras, who speaks about the intellect that rules all things, so that it would not be supposed that his own conclusion concerned that intellect, he uses the following manner of speaking: "Therefore the intellect that is said of the souland I mean the intellect by which the soul thinks and understandsis in no respect in act,"62 etc. From this two things are clear: First, that he is not speaking here of an intellect which is a separate substance, but of the intellect which he had said above63 55 Aristotle, De Anima, III, 4, a See also I, 2, a , and Met.

I, 8, a b 20; Diels, op. Secondly, that which he proved through what was said above, that is, that the intellect does not have a nature that is in act. But he has not yet proved that it is not a power in the body, as Averroes says;64 but he immediately concludes this from the preceding; for this follows: "Wherefore it is not reasonable to suppose that it is mixed with a body. From this it is clear that it is not mixed with a body, because if it were mixed with a body, it would have some of the corporeal natures.

And this is what he adds: "For an intellect would surely become of some kind, either hot or cold, if it were to have an organ like a sense faculty. Therefore the operation of the sense is changed even according to the change of the organ. This therefore is the meaning of the expression, ''not to be mixed with body," that intellect does not have an organ as the sense does.

And that the intellect of the soul does not have an organ, he shows67 by the remark "of certain men who said that the soul is the place of species," taking "place" in its broad meaning as anything receptive, in the manner of the Platonists; except that to be the place of species does not pertain to the whole soul, but only to the intellective [power].

For the sensitive part does not receive the species in itself but in its organ; whereas the intellective part does not receive them in an organ, but in itself. Besides, the intellect is not the place of species in such a way that it has them in act, but only in potency. Since, therefore, he has now shown what pertains to the intellect from its likeness with sense, he comes back to his first statement, that is, that "the intellective part must be impassible,"68 and so by a wondrous subtlety, from its very similarity with sense, he concludes its dissimilarity.

He therefore shows subsequently "that sense and intellect are not impassible in the same way,''69 inasmuch as sense is injured by an excessively intense sensible, but the intellect is not injured by an excessively intense intelligible. And from what has already been proved, he states as the cause of this, "that the sense [power] does not exist without a body, but the intellect is separate.

See Comm. Foreword: Statement of Purpose and Method: This is not the view of Aristotle: Chapter I: 1. De Anima of Aristotle excludes an Averroistic interpretation: a. Analysis of Aristotle's definitions of soul: b. Interpretation of words at beginning of III de Anima: c. Analysis of Aristotle's references to Empedocles and Anaxagoras: 2. Interpretation of a text from Physics: 3. Refutation of objections: B. This is not the view of the Peripatetics: Chapter II: 1. Greeks: 2. Arabs: 3. Conclusion: 59 C.

This is not the view of sound philosophy: Chapter III: 1. Arguments by which one can establish that the intellective soul is the substantial form of man: a. Principal argument: 1 Statement of argument proceeding from this undeniable fact: Hic homo singularis intelligit: 2 Averroes' view fails to explain this fact: Argument proceeding from a consideration of man as a member of the human species: 80 c.

Argument based on requirements of moral order: 2. Refutation of objections proposed by Averroists: III. Is the Intellect One for all Men? The possible intellect is not one for all men: Chapter IV: 1. Unicity of the intellect involves absurd consequences: Unicity of the intellect is incompatible with Aristotle's doctrine: 3. No matter how the relation of the intellect to our phantasms is understood, the doctrine of one possible intellect for all men cannot explain human knowledge: B. Objections against the plurality of possible intellects, and refutations of these objections: Chapter V: C. Thomas' time, it was not just an occasional or ephemeral work.

It touches upon some very basic and vital questions which surpass in their reach, the limits of a thirteenth century polemic. For example: 1 What is the soul? Thomas' treatment of these and other questions in the De Unitate is notable for its clarity of expression and the depth of his philosophical insight. Father Leo W. Thomas' text. It includes Keeler's section numbers to facilitate reference to the text, and Keeler's titles for chapters and parts of chapters. Although using Keeler's notes as a guide, it does not reproduce them exactly.

The bibliography which follows in Section F, is intended to direct the reader to works that will aid in the understanding of the background and content of the De Unitate, and of some of the main problems with which the treatise is concerned. Selected Bibliography Aristotle, De Anima, tr. Smith, in The Basic Works of Aristotle, ed. Cambridge, Mass. Chossat, M. Gilson, E.

The Christian Philosophy of St. Elements of Christian Philosophy, Chapters New York: Scribner's, Keeler, L. Thomas' 'De unitate intellectus,'" Gregorianum 17 , Rome: Gregorian University, , , Mandonnet, P. Pegis, A. Thomas and the Unity of Man," pp. Milwaukee: Bruce, Robb, J. Thomas Aquinas, St.

Tractatus de Unitate Intellectus contra Averroistas, critical edition by L. The Soul: A Translation of St. Thomas Aquinas' De Anima, by J. Louis: Herder, Aristotle's De Anima with the Commentary of St. Thomas Aquinas, tr. New Haven: Yale University Press, On Spiritual Creatures, tr. Fitzpatrick and J. New York: Doubleday Image Books, Summa Theologiae I, pp.

Thomas Aquinas, I, tr. Van Steenberghen, F. Aristotle in the West, tr. Louvain: Nauwelaerts, Verbeke, G. Louvain: Publications Universitaires de Louvain, Foreword1 1. Just as all men naturally desire to know the truth,2 so there is inherent in men a natural desire to avoid errors, and refute them when they are able to do so. Now among other errors, the error that seems especially inappropriate is the one concerning that very intellect through which we are meant by nature to avoid errors and know the truth. For a long time now there has been spreading among many people an error concerning the intellect, arising from the words of Averroes.

The numbers preceded by " " are Keeler's section numbers. In his Commentarium Magnum in Aristotelis de Anima Libros Averroes cites Alexander's views, borrows his term, but differs from him on the nature of the material or possible intellect; see in the critical edition of The Mediaeval Academy of America, Cambridge, Mass. It is not now our intention to show that the above-mentioned position is erroneous in this, that it is opposed to the truth of the Christian Faith. For this can easily enough become evident to everyone. For if we deny to men a diversity of the intellect, which alone among the parts of the soul seems to be incorruptible and immortal, it follows that after death nothing of the souls of men would remain except that single substance of intellect; and so the recompense of rewards and punishments and also their diversity would be destroyed.

However, we intend to show that the above-mentioned position is no less against the principles of philosophy than against the teachings of Faith. And because, so they say, the words of the Latins on this subject have no savor for some persons, but these men say that they follow the words of the Peripatetics, whose books on this subject they have never seen, except those of Aristotle who was the founder of the Peripatetic Sect;8 we shall show first that the above-mentioned position is entirely opposed to his words and meaning.

Thomas accuses the Averroists of knowing authorities only as they were quoted by Averroes, who himself ''was not so much a Peripatetic as a perverter of Peripatetic philosophy. Chapter I. Aristotle did not teach that the possible intellect is a substance separate in its being from the body. The definition of the soul that Aristole gives, belongs also to the intellective soul. The first definition of the soul that Aristotle sets down in Book II of the De Anima, saying that "the soul is the first act of a physical organic body,"1 should be accepted.

And lest perhaps someone might say that this definition does not apply to every soul2 because of the fact that Aristotle had previously qualified his treatment by saying: "If it is necessary to say that there is something common to every soul,"3 which they interpret as meaning that this could not be, the words of his that follow should be accepted. For he says: "It has been stated in a universal way what the soul is. For a substance is what it is by definition; now this is the essence of this body,''4 that is, the substantial form of a physical organic body.

And lest perhaps it be said that the intellective part is excluded from this universal statement, this is answered by what he says afterwards: "It is indeed clear therefore that the soul is not separable from the body, or that certain of the soul's parts are [not separable], if it naturally has parts, for it is the act of the certain parts themselves.

But truly nothing prevents certain parts [from being separable] since they are not the acts of any body. From this it is clearly shown concerning that soul which Aristotle had defined above in a universal way as the act of the body, that it has some parts which are acts of some parts of the body, but also some which are acts of no body.

For it is one thing for the soul to be the act of the body and another for part of it to be the act of the body, as will be shown later. Thomas, Comm. For the soul is also said to be that by which we first live and understand. But it becomes still clearer from what follows that the intellect is also included under this general definition.

For although he has sufficiently proved that the soul is the act of the body since when the soul is separate from it, the body is not actually living ,8 yet something can be said to be actually such by the presence of something, not only if it is a form but also if it is a mover just as what is combustible is actually burned by the presence of something burning, and whatever is movable is actually moved by the presence of something moving.

For this reason someone could come to doubt whether a body is actually living by the presence of a soul in the way in which what is movable is actually moved by the presence of a mover, or in the way in which matter is in act by the presence of form.

And especially because Plato held that the soul is not united to the body as its form but rather as its mover and ruler, as is clear through Plotinus and Gregory of Nyssa;9 I mention these because they were not Latins but Greeks. This doubt therefore is what the Philosopher is hinting at when he adds to what he has said: ''But further, it is unclear whether the soul is the act of the body in the way that a sailor is of a ship. Then because after what he had said, this doubt still remained, he concludes: "The soul is thus indeed defined and described in a general way,"11 because he had not yet clearly demonstrated the truth.

To remove this doubt therefore, he next proceeds to show that which is more certain both in itself and in knowledge, through those things that are less certain in themselves but more certain to us, that is, through the effects of the soul which are the acts of the soul. Then he at once distinguishes the works of the soul, saying that "the animate is distinguished from the inanimate inasmuch as it is living," and that there are many things which pertain to life, namely, "intellect, sense, motion and position according to place, and the motion of nourishment and growth" so that "in whatever being any of these is found, that thing is said to live.

Thomas seems to be referring to passages that he cites in 76, See notes to these sections. And Plato held that there are diverse souls in man, according to which distinct vital operations belong to him. And he adds that "in some cases this does not seem difficult, but some cases raise a question. But he shows which points he considers questionable when he adds that "nothing is as yet evident concerning the intellect and perceiving power. And although he says this is not yet clear, yet he shows what is apparent on this point at first glance when he adds: "But it seems to be another genus of soul.

And because the corruptible and eternal do not seem able to come together into one substance, it seems that of the parts of the soul, it belongs to this part alone namely the intellect to be separated not indeed from the body, as the Commentator wrongly explains,22 but from the other 15 Plato, Timaeus 89EA, 69CA, in B. Jowett tr. Averroes cites Plato in In de Anima I, comm. And that it must be understood in this way is evident from the following: "As for the remaining parts of the soul, it is clear from what has been said that they are not separable,"23 that is, either with regard to subject or to location.

For this was the question put above, and this is what was proved from what was said above. And that it is not to be understood to concern separability from the body, but separability of the powers from one another, is clear from what follows: "That they are different in definition," that is different from one another, ''is clear. For the sensitive is different from the opinionative.

For the question above was whether one part of the soul is distinct from another part only by reason, or also separate in location. Having here dismissed that question with regard to the intellect, about which he settles nothing here, he says concerning the other parts of the soul that clearly they are not separable, that is in location, but they are distinct by reason. With this point secured, that the soul is specified by the vegetative, sensitive, intellective, and motive [powers], he wishes to show next that as regards all those parts, the soul is united to the body not as a sailor to a ship, but as form.

And thus, what the common meaning of soul is, which had been treated above only in a general way, will have been established. And so it is clear that knowledge is the form of the soul as health is of the body. From this he develops his argument as follows: "The soul is the first principle by which we live this he says because of the vegetative power , by which we sense because of the sensitive power , by which we are moved because of the motive power , and by which we understand because of the intellective power ; and he concludes: "Wherefore the soul will undoubtedly be a certain definable form and 23 Aristotle, De Anima II, 2, b See also 7 of De Unitate Intellectus and Comm.

See also St. Therefore what Aristotle meant was that that by which we understand is the form of a physical body. But lest anyone say that that by which we understand does not mean here the possible intellect, but something different, clearly this is excluded by what Aristotle says in III De Anima, when speaking of the possible intellect: "I speak moreover of the intellect by which the soul thinks and understands.

Aristotle states that the intellect is a power of the soul which is the form of the body. But before we take up the words of Aristotle which are in III De Anima, we should dwell still further on his words in II De Anima, so that from a comparison of his words with each other, it may be clear what his teaching on the soul was. For when he had defined the soul in general, he begins to distinguish its powers; and he says that "the powers of the soul are vegetative, sensitive, appetitive, locomotive, intellective. And that he had said that the intellect is a power of this soul and that the definition of the soul stated above is common to all the parts mentioned before is evident from his conclusion: "Therefore it is clear, since there will undoubtedly be one definition of soul in the same way as there is one of figure; for the figure is not there as something over and beyond the triangle and the others that follow from it; nor is the soul here as something over and beyond the parts mentioned.

Aristotle makes no further mention of the intellect in Book II, except his later remark that "the last and the least he says is reason27Ibid. And see St. But because there is a great difference as regards the mode of operation, between the intellect and the imagination, he adds that "the notion of the speculative intellect is different. And lest anyone should say, as Averroes wrongly explains,34 that the reason Aristotle says that the notion of the speculative intellect is different is that the intellect is neither the soul nor a part of the soul, he immediately excludes this at the beginning of Book III,35 where he takes up again the treatment of the intellect.

For he says: "As for the part of the soul by which the soul knows and understands. Moreover, the wonderful carefulness and order in Aristotle's procedure must be considered. Now he had previously left two things unsettled about the intellect. First, whether the intellect is separated from the other parts of the soul only by reason, or also in location; this he had left unsettled when he said: "Nothing is as yet evident concerning the intellect and perceiving power.

Thomas follows the division of books as they are in the Greek copies, in this work because he is concerned with Averroes and the Averroists , he uses the division which the Arabs used, according to which Book III begins with Chapter 4 of Book III of the Greek a See De Unitate Intellectus, 7. Secondly, he had left unsettled the difference between the intellect and the other parts of the soul, when he said afterwards: "But the notion of the speculative intellect is different.

The very manner of speaking makes this sufficiently clear. For he says that it should be considered what the intellect's difference from the other parts of the soul is, whether it is separable from them in size or location, that is in subject, or not separable in that way but only by reason. The intellect is compared with sense. Empedocles and Anaxagoras. But because in certain words that follow, the Averroists wished to understand Aristotle's meaning to have been that the intellect is not the soul which is the act of the body, or part of such a soul;46 for that reason his next words must be considered even more attentively.

Immediately therefore after the question proposed about the difference between the intellect and sense, he asks47 in what respect intellect is like sense and in what respect it is different from it. For he had pre41Ibid. See De Un. Siger of Brabant is reported by John Baconthorp to have said that if by intellect we mean the immaterial possible intellect that we call the intellective soul in us, then the Philosopher does not prove that the intellective soul is the form of man. John of Baconthorp, Quodlibeta Venice, , fol.

See M. Chossat, "St. This therefore is what Aristotle is trying to point out when he says: "If therefore understanding is like sensing, either it will surely suffer from an intelligible object," inasmuch as intellect would be injured by an excessively intense intelligible object as sense by an excessively intense sensible, "or something of this kind, yet different.

To this question therefore he immediately answers; and he concludes not from what precedes but from what follows, although what follows is clear from what precedes that this part of the soul "must be impassible"50 so that it is not injured, as is sense. It has however another kind of passivity, inasmuch as understanding is said in a general way to suffer. In this respect, therefore, it differs from sense. But next he shows how it is like sense, because, namely, a part of this kind must be "receptive of an intelligible species," and be "in potency" to a species of this kind, and "not be this'' in act according to its own nature;51 just as it was previously said about sense, that it is in potency to sensible things, and not in act.

But this led to the exclusion of the opinion of Empedocles and other ancient thinkers who stated that the knower is of the nature of the thing known, for example that we know earth inasmuch as we are earth, and water inasmuch as we are water.

Averroes' theory of the unity of the intellect - Wikipedia

But there is a difference between sense and intellect, because a sense is not able to know all things, but sight can know only colors; hearing, only sounds; and so for the rest; whereas the intellect is able to know all things without such limitations. Now the ancient philosophers used to say, since they were of the opinion that the knower must have the nature of the thing known, that the soul, in order to know all things, must be a mixture of the principles of all things.

But because Aristotle already proved through a comparison with sense, that the intellect is not actually but only potentially that which it knows, he concluded to the contrary that "because the intellect knows all things, 48 Aristotle, De Anima II, 11, b 30 - al; a 25 -b3. Diels, Die Fragmente der Vorsokratiker, fr. And to show this, he brings in the testimony of Anaxagoras,56 who was not, however, speaking about this same intellect, but about the intellect that moves all things.

Therefore just as Anaxagoras said that that intellect was unmixed, so that it might rule by moving and separating out, so we can say about the human intellect that it must be unmixed so that it may know all things; and this he proves thereafter and so the following line is found in the Greek: "That which appears within will hinder and obstruct what is without.

Likewise, if the nature of the things which the intellect knows, for example, earth or water, what is hot or cold, or anything of this kind, were intrinsic to the intellect, that nature within the intellect would hinder and in some way prevent the intellect from knowing other things. Because therefore it knows all things, he concludes59 that "it cannot itself have any nature" which is determined by the sensible natures that it knows; "but it has this nature alone, that it is possible," that is, in potency to those things that it knows, so far as its own nature is concerned; but it becomes those things in act during the time in which it actually knows them; as the sense in act becomes the sensible in act, as he had said above in Book II.

And because he had mentioned the statement of Anaxagoras, who speaks about the intellect that rules all things, so that it would not be supposed that his own conclusion concerned that intellect, he uses the following manner of speaking: "Therefore the intellect that is said of the souland I mean the intellect by which the soul thinks and understandsis in no respect in act,"62 etc. From this two things are clear: First, that he is not speaking here of an intellect which is a separate substance, but of the intellect which he had said above63 55 Aristotle, De Anima, III, 4, a See also I, 2, a , and Met.

I, 8, a b 20; Diels, op. Secondly, that which he proved through what was said above, that is, that the intellect does not have a nature that is in act. But he has not yet proved that it is not a power in the body, as Averroes says;64 but he immediately concludes this from the preceding; for this follows: "Wherefore it is not reasonable to suppose that it is mixed with a body. From this it is clear that it is not mixed with a body, because if it were mixed with a body, it would have some of the corporeal natures.

And this is what he adds: "For an intellect would surely become of some kind, either hot or cold, if it were to have an organ like a sense faculty. Therefore the operation of the sense is changed even according to the change of the organ. This therefore is the meaning of the expression, ''not to be mixed with body," that intellect does not have an organ as the sense does. And that the intellect of the soul does not have an organ, he shows67 by the remark "of certain men who said that the soul is the place of species," taking "place" in its broad meaning as anything receptive, in the manner of the Platonists; except that to be the place of species does not pertain to the whole soul, but only to the intellective [power].

For the sensitive part does not receive the species in itself but in its organ; whereas the intellective part does not receive them in an organ, but in itself. Besides, the intellect is not the place of species in such a way that it has them in act, but only in potency. Since, therefore, he has now shown what pertains to the intellect from its likeness with sense, he comes back to his first statement, that is, that "the intellective part must be impassible,"68 and so by a wondrous subtlety, from its very similarity with sense, he concludes its dissimilarity. He therefore shows subsequently "that sense and intellect are not impassible in the same way,''69 inasmuch as sense is injured by an excessively intense sensible, but the intellect is not injured by an excessively intense intelligible.

And from what has already been proved, he states as the cause of this, "that the sense [power] does not exist without a body, but the intellect is separate. See Comm. Now it is especially this last word that they take over to support their error, intending by this to hold that the intellect is neither the soul nor a part of the soul, but some separate substance. For he says here that "the sense power does not exist without a body, and the intellect is separate," as he said above that the intellect "would become of some kind, either hot or cold, if it were to have an organ like a sense faculty.

Most clearly therefore it appears without any doubt, from the words of Aristotle that this was his position about the possible intellect, namely that the intellect is something belonging to the soul which is the act of the body; but in such a way that the intellect of the soul does not have a corporeal organ as the other powers of the soul have. The interpretation stated above is confirmed by Physics II, 2.

Now how it is possible that the soul is the form of the body and some power of the soul is not a power of the body, is not hard to understand if one would consider [the point] in other things as well. For we see in many instances that a form is indeed the act of a body made of a mixture of elements, and yet it has some power which is not the power of any element, but which belongs to such a form by reason of a higher principle, for example, a celestial body; just as a magnet has the power of attracting iron, and jasper of checking the blood flow.

Whence the highest of the forms, which is the human soul, has a power totally transcending corporeal matter, namely the intellect. Nor do we say that the soul in which the intellect is, so exceeds corporeal matter that it does not have its being in the body; but that the intellect, which Aristotle calls a power of the soul, is not the 71 Averroes, In de Anima II, comm.

Albert says of jasper that it stops the flow of blood: De Mineralibus, Lib. II, tract. II, cap. Thomas, Q. For the soul is not the act of the body through the mediation of its powers, but the soul through its own self is the act of the body, giving specific being to the body. Some of its powers, however, are acts of certain parts of the body, perfecting them [the parts] for some operations. On the other hand, such a power as the intellect is the act of no body, because its operation is not accomplished through a corporeal organ.

And lest it seem to anyone that we are saying this from our own interpretation and beyond Aristotle's meaning, we should quote the words of Aristotle saying this expressly. And he solves the question by adding: "To what extent does a doctor know a nerve, or an artisan know bronze? And he shows to what end by adding: "until he knows the purpose of each. And because a physicist considers form insofar as it is in matter for such is the form of a movable body , in a similar way it must be understood that the natural philosopher considers form in so far as it is in matter.

The end therefore of the physicist's consideration of forms, is in the forms which are in a certain way in matter, and in another way not in matter. For such forms are on the boundary of separate and material forms. It is therefore not impossible that some form be in matter, and its power be separate, as has been explained concerning the intellect.

Thomas, Sum. I, q 77, a. Bardenhewer , p. II, 2, b Keeler points out that according to Aristotle, all generation and corruption depends on the annual motion of the sun, in so far as it draws near and recedes. Reply to someone arguing that the intellect is incorruptible according to the Philosopher, and therefore not the form of a corruptible body. But in still another way they proceed to show that it was Aristotle's teaching that the intellect is not the soul, or part of the soul that is united to the body as its form.

For Aristotle says in several places that the intellect is eternal and incorruptible, as is clear in Book II of the De Anima, where he said: "It belongs to this alone to be separated as the eternal from the corruptible;"83 and in Book I, where he said that "the intellect seems to be some kind of substance and is not corrupted;"84 and in Book III where he said: ''Only when separated is it what it truly is, and this alone is immortal and eternal,"85 although this last [statement] certain men explain as concerning not the possible intellect, but the agent intellect.

From all these words it is clear that Aristotle meant that the intellect is incorruptible. But it seems that nothing incorruptible can be the form of a corruptible body. For it is not accidental to form, but it is proper to it of itself that it be in matter; otherwise only an accidental union would result from matter and form.

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Now nothing can exist without that which properly inheres in it. Therefore the form of a body cannot be without a body. If therefore a body be corruptible, it follows that the form of a body is corruptible. Besides, the forms which are separate from matter and the forms which are in matter are not the same in species, as is proved in Book VII of the Metaphysics. Therefore when the body is destroyed, either the form of the body is destroyed, or it goes into another body.

If therefore the intellect is the form of the body, it seems to follow necessarily that the intellect is corruptible. Now it should be noted that this reasoning influenced the Platonists. In 36 St. Thomas comments directly on the interpretation of this line. VII, 11, b , a ; 16, b 28 - a4. For an account of how the work of Nemesius was attributed to Gregory in the Middle Ages, Keeler refers the reader to the article by E.

On account of this [reasoning] some men in fact held that the soul goes from body to body. Some have even held that the soul would have some kind of incorruptible body from which it would never be separated. For in Book XI of the Metaphysics, after he had shown that forms do not exist prior to matter, "since when a man is cured, then health exists, and the shape of a bronze sphere exists together with the bronze sphere;"89 he next asks whether any form remains after the matter, and he says yes, according to the translation of Boethius: "Whether indeed, there remains something afterwards that is, after the matter , must be considered.

For in certain cases nothing would prevent this, as for example if the soul is of this kind, not all the soul, but the intellect, for perhaps it is impossible for all the soul. For since he had said absolutely that "moving causes are prior, but not formal causes,''91 his question was not whether any form was prior to matter, but whether any form may remain after matter; and he says that nothing prevents this with respect to a form which is the soul, so far as its intellective part is concerned.

Since therefore, according to the foregoing words of Aristotle, this form which is the soul may remain after the body, not the whole soul, but the intellect, it should be considered why the soul remains 88 Keeler notes that some of the ancient neoplatonists esp. Proclus admitted some such thing, and that St. Thomas usually refers to this doctrine as "Platonic" without naming any author, as in Sum. See Proclus, Elements of Theology, prop.

Augustine, City of God X, XII, 3, a He refers to M. Dondaine, Bulletin Thomiste pp. See also D. Salman, O. Thomas through Indeed, it is necessary to take the explanation of this from the very words of Aristotle. For he says: "But only when separated is it what it truly is, and this alone is immortal and eternal. But there can be a doubt concerning what he is talking about in this text.

Some say93 he is talking about the possible intellect; some say that it is about the agent intellect. Each of these seems to be false if the words of Aristotle are carefully considered. For Aristotle had said of each [the agent and the possible intellect] that it is separate. Therefore it must be understood of the whole intellective part, which indeed is called separate because it has no organ, as is clear from the words of Aristotle.

Now Aristotle had said in the beginning of the book, De Anima, that "if there is some work or passion proper to the soul, then the soul can certainly be separated; but if there is none proper to it, it certainly will not be separable. The forms, therefore, which have no operation without being joined with their matter, do not themselves operate, but it is the composite that operates through the form. Whence indeed, forms of this kind do not themselves, properly speaking exist, but by means of them something exists.

For just as it is not heat, but a hot thing, that heats; so also heat is not properly said to exist, but a hot thing exists through heat. On account of this Aristotle says in Book XI of the Metaphysics that it is not truly said of accidents that they are beings, but rather that they are of being. And the reasoning is similar with respect to substantial forms which have no operation without being joined to matter, with this exception that forms of this kind are the principle of being substantially. The form, therefore, which has an operation according to some potency or power of its own apart from being joined with its matter, is that which itself has being, nor does it exist only through the being 92 Aristotle, De Anima III, 5, a XII, lect.

And, therefore, when the composite is destroyed, there is destroyed that form which exists through the being of the composite, whereas there is no need that, upon the destruction of the composite, there be destroyed that form through whose being the composite exists and which does not itself exist through the being of the composite. But someone might bring as an objection against this, what Aristotle says in Book I of the De Anima, that "to understand and to love and to hate are not passions of that that is, of the soul , but of the one having that insofar as he has that; wherefore when this composite is corrupted, it [the soul] neither remembers nor loves, for these activities did not belong to that [the soul], but to the composite which has been destroyed.

Whence in that whole chapter he speaks of intellect as he speaks of sense. This is especially evident where he proves that the intellect is incorruptible by means of the example of sense, which is not corrupted by old age. Wherefore, through the whole chapter, he speaks conditionally and with doubt as an inquirer, always joining those things which pertain to the intellect to those which pertain to the sense; this is especially clear from what he says in the beginning of the solution: "For if and most especially, to feel pain and to be glad and to understand" etc.

Now if anyone should ask further: if the intellect does not understand without a phantasm, how then will the soul have an intellectual operation, after it has been separated from the body? Whence Aristotle, in speaking of the soul in Book II of the Physics, says: "But it is the work of first philosophy to determine how this separable thing 96 Aristotle, De Anima I, 4, b Verbeke Louvain: Publications Universitaires de Louvain, Whence it is not without cause that Aristotle asks in Book III of the De Anima "whether the intellect that is not separate from a body may know something separate.

In these words it must also be carefully noted that, although he had said above that both intellects i.

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For intellect is separate, inasmuch as it is not the act of an organ; but it is not separate inasmuch as it is a part or power of the soul which is the act of the body, as was said above. But from what he says in the beginning of Book XII of the Metaphysics and I have seen 10 of these books, though not yet translated into our language , it can most certainly be concluded that Aristotle solved questions of this kind in what he evidently wrote concerning separate substances.

According to this, therefore, it is clear that arguments brought forth to the contrary do not demonstrate with necessity. For it is essential to a soul that it be united to a body, but this is hindered accidentally, not because of the soul, but because of the body which is corrupted. Just as it belongs essentially to a light thing to be up, and "this is the to be for a light thing, that it be up," as Aristotle says in 99 Aristotle, Phys. XIII, 1, a This is the reference that Keeler gives.

He says that St. See note 90 However, Salman would rather give the reference as Met. VII , p. The reference to the ''10 books" should read, according to Salman, "14 books,'' as given in the Mandonnet edition of the Opuscula, I, p. Thomas might have been thinking of the apocryphal work, The Theology of Aristotle, which consists of ten sections, Salman rejects this theory and says that St.

Thomas was rather referring to the parts of the Metaphysics he had not yet read. See Salman, op. What St. Thomas says in the last sentence of De Un. For that which has the nature of being up and that which does not have the nature of being up differ in species; and yet that which has the nature of being up is the same in species and number although sometimes it is up and sometimes, on account of some hindrance, it is not up.

So similarly, two forms, one of which has the nature of being united to a body, but the other does not have such a nature, differ in species; but yet something having the nature of being united to the body can be one and the same in species and number, although sometimes it is actually united and sometimes, on account of some hindrance, it is not actually united. Three other objections to the Philosopher's words are declared invalid. But they still take up for the support of their error what Aristotle says in the book, On the Generation of Animals, that is, "the intellect alone comes from without and it alone is divine.

Therefore, the intellect is not the form of the body. They also object that every from of a mixed body is caused from the elements. Whence, if the intellect were the form of the human body, it would not be from something without, but would be caused from the elements. They also have an additional objection about this, because it would follow that the vegetative and sensitive [powers] would also be from without.

This is contrary to Aristotle, especially if there be one substance of soul whose powers would be vegetative, sensitive, and intellective; for the intellect is from without, according to Aristotle. Now the solution of these objections readily appears according to what has already been said. For when it is said that every form is educed from the potency of matter, it would seem that we ought to consider what it means that form be educed from the potency of matter. For if it means nothing else than that matter preexists in potency to form, nothing prevents one from saying that in this sense corporeal matter preexists in potency to the intellective soul: whence Aristotle says in the book, On the Generation of Animals: "First indeed all [animals] seemed to live thus namely the separated of foetuses Aristotle, Phys.

VIII, 4, b But consequently it is evident that it should be said of the sensitive soul and of the active and of the intellective soul; for everything necessarily has potency prior to act. But because potency is referred to an act, it is necessary that each thing be in potency according to the same nature which is proper to it as being in act. But it has already been shown that it is proper for other forms which have no operation apart from union with matter, to be in act in such a way that they are more properly forms by which the composites exist, and in some way co-existing with the composites, rather than being forms that possess their own being.

Whence just as their whole being is in their being joined with matter, so they are said to be totally educed from the potency of matter. But the intellective soul, since it has an operation apart from the body, is not its own being only in its being joined with matter. Whence it cannot be said that it is educed from matter, but rather that it is from an extrinsic principle.

And this is clear from the words of Aristotle: "But it remains that intellect alone comes from without, and it alone is divine," and he gives the reason by adding: "For the operation of the body does not at all share in its operation. But I wonder what is the source of the second objection, namely that if the intellective soul were the form of a mixed body, that it would be caused from a mixture of the elements, since no soul is caused from a mixture of the elements. For there exists in the seed of everything that which makes the seeds to be generative, and this is called heat.

But this is not fire nor any such power, but is some spirit which is contained in the seed and in the foaming thing. And in this spirit, the nature is proportional to the ordering of the stars. Now as for the third objection, that it would follow that the vegetative and sensitive [parts] are from without, it is not to the point. For it is already clear from Aristotle's words that he leaves it unsettled whether the intellect differs from the other parts of the soul in subject and location, as Plato said, or only by reason. See Sum. II, 62, II, 73; Sum.

But if it be granted that they are the same in subject which is closer to the truth , thus far no difficulty results. Both in figures and in living things, it is always true that prior things exist potentially in what succeeds them; as a triangle exists in a square, so is the vegetative in the sensitive. But if that which is the same in subject is also intellective which he leaves doubtful , it must similarly be said that the vegetative and sensitive are in the intellective, as a triangle and square are in a pentagon.

Now a square is indeed a figure that is, without qualification, other in species than a triangle, but not other than the triangle that is potentially in it; just as the figure 4 is not other than the figure 3 that is part of itself, but it is other than the figure 3 that exists apart from it. And if it should happen that diverse figures are produced by diverse agents, of course a triangle existing apart from a square would have another producing cause than the square would have, just as it also has another species; but the triangle that is in the square would have the same producing cause.

So therefore the vegetative [soul] that exists apart from the sensitive, is indeed another species of soul and has another productive cause; yet there is the same productive cause for the sensitive and for the vegetative which is within the sensitive. If therefore it be stated in this way: that the vegetative and sensitive [parts] which are present within the intellective [part], are from the extrinsic cause which is the cause of the intellective part, no difficulty results.

For it is not unsuitable that the effect of a superior agent should have a power that the effect of an inferior agent has, plus still more. Whence also the intellective soul, although it be from an external agent, nevertheless has powers which the vegetative and sensitive souls, coming from inferior agents, also possess. So therefore, from this careful consideration of almost all the statements which Aristotle made about the human intellect, it is clear that his position was that the human soul is the act of the body, and that the possible intellect is a part or power of that soul.

Thomas, In de Anima II, lect. Chapter II. What other Peripatetics thought about the relation of the possible intellect to man. The Greeks: Themistius, Theophrastus, Alexander. Now we must consider what other Peripatetics thought on this point. And first let us take the words of Themistius in the Commentary on the Soul, where he speaks as follows:1 "That intellect which we say is in potency.

And just as light coming to sight and colors in potency, makes sight and colors to be in act, so also that intellect which is in act. For this reason it is within our power to understand whenever we wish. For art is not of exterior matter. In this way, the intellect which is in act, supervening upon the intellect in potency, is made one with it. And after a few words he concludes:2 "We therefore are either the intellect which is in potency or the intellect which is in act. If indeed in all things composed of that which is in potency and of that which is in act, to be this is one thing and the to be of this is another, then I ego and my to be will be different.

And I ego am the intellect composed of potency and act, but my to be is from that which is in act. Wherefore, both what I think and what I write, the intellect composed of potency and act writes; yet it does not write in so far as it is in potency, but insofar as it is in act; for thence its operation is derived.

Verbeke, see note 97 VI, pp. Keeler notes that one reason why St. Thomas makes so much of Themistius in the De Unitate Intellectus is that in his previous works he had followed the interpretation of Themistius handed down by Averroes. This he considers to be erroneous, now that he has read the version recently translated by William of Moerbeke.

My to be therefore, is from the soul, but not from every [part of the soul]. My to be is not from the sensitive [part], for this is matter in relation to imagination. Nor again from the imaginative [part], for this is matter in relation to intellect which is in potency. Nor is my to be from that intellect which is in potency for this is matter in relation to the factive intellect.

Therefore my to be is from the factive intellect alone. We accordingly, are the active intellect. And afterwards, rejecting the opinion of certain men, he says:a "Since he Aristotle had said that in every nature there is matter and that which moves and perfects matter, it must needs be that these differences also exist in the soul, and that there must be some intellect which is such by becoming all things, and another which is such by making all things.

For he says that in the soul there is such an intellect and that it is, as it were, the most honorable part of the human soul. I have not indeed seen the books of Theophrastus, but Themistius in his Commentary, introduces his words to this effect, saying thus:4 "Now it is better to set forth the words of Theophrastus both about the intellect in potency and that which is in act. Concerning the one, therefore, which is in potency, he says this: Now how is the intellect existing from without and as if superimposed, and yet connatural? And what is its nature?

For indeed it is nothing in act, but it is surely everything in potency, as sense is. For it must not be so understood that it itself does not existfor this is a point of disputebut that it is a kind of potency as a subject, as is the case in material things. But this from without, therefore, should be understood not as something added, but as included at the very beginning of generation. Zeller discusses Theophrastus in Aristotle and the Earlier Peripatetics, tr.

Costelloe and J. II, He cites this passage on p. So therefore, Theophrastus, when he had asked two questions: first, how is the possible intellect from without and yet connatural to us; and secondly, what is the nature of the possible intellect, answers the second question first. He says that the possible intellect is in potency to all things, not indeed as being nothing existing, but as sense [is in potency] to sensibles. And from this he draws his answer to the first question, that it is not so understood to be from without as though it were something added accidentally or in some former time, but [is] from the very beginning of generation as though containing and including human nature.

Moreover, that Alexander held that the possible intellect is the form of the body, even Averroes himself admits, although as I think he understood the words of Alexander wrongly, just as he had also taken the words of Themistius beyond his meaning. For what he says5 is that Alexander has said that the possible intellect is nothing other than a preparation which is in human nature, a preparation for the agent intellect and the intelligibles; he [Alexander] understood this preparation to be nothing other than the intellective potency in the soul for intelligibles.

And this is the reason he said it is not a power in the body,because such a potency does not have a corporeal organ; it is not for the reason that Averroes opposes, namely that no preparation is a power in the body. Arabs: Avicenna, Algazel. To pass now from the Greeks to the Arabs: first it is clear that Avicenna held that the intellect is a power of the soul which is the form of the body. For so he says in his book On the Soul: "The active intellect i. Moreover, the contemplative intellect needs the body and its powers, but not always nor completely. Keeler notes that in Comm.

II, d. II, 62, St. Thomas followed the exposition of Alexander's doctrine that Averroes had handed down. However, when he later discovered that the genuine opinion of Themistius came much closer to his own Peripateticism than appeared from the writings of the Commentator, he began to suspect that the Commentator had also given a poor interpretation of Alexander. He therefore imposed a Thomistic interpretation upon Alexander. Keeler adds that such an interpretation is erroneous and that the true mind of Alexander is given with sufficient accuracy in the long and laborious exposition of Averroes.

Alexandre d'Aphrodise, pp. Keeler concludes by observing that it is remarkable that St. Thomas did not have recourse to the fragment of Alexander, the De Intellectu ed. Moreover, none of these [powers] is the human soul; but the soul is that which has these powers and, as we shall later make clear, is a solitary substance, i. Some of these actions are not perfected in any way except through instruments and their use; but there are some for which instruments are not necessary in any way. Next must be added the words of Algazel, who speaks thus: "When the mixture of the elements will have been of a more beautiful and more perfect equality, than which nothing more subtle or more beautiful can be found.

Now of this human soul there are two powers: one operative and the other cognitive. And yet he later proves by many arguments, that the operation of the intellect is not accomplished through a corporeal organ. Now these things we have said first, not as though wishing to reject the above error by the texts of the philosophers; but to show that not only the Latins, whose words some do not relish, but also the Greeks and the Arabs were of this opinion: that the intellect is a part 6 Avicenna, De Anima V, c.

Louis University, Keeler notes that the text of Avicenna cited by St. Thomas coincides almost completely with that which is found in the Venice, edition. Klubertanz, p. IV, c. Muckle ed. Michael's College, Albert and St. Thomas, they took Algazel's summary of Avicenna's philosophy to be a statement of his own position. Zedler Milwaukee: Marquette University Press, , pp. Wherefore I wonder from which Peripatetics they boast of having taken this error, unless perchance they are less willing to be right with other Peripatetics than to be wrong with Averroes, who was not so much a Peripatetic as a perverter of Peripatetic philosophy.

Chapter III. It is proved by reason that the intellect is a power of the soul which is the form of the body. Aristotle's argument: That the soul is that by which we first understand. Since it has been shown from the words of Aristotle and of others who follow him that the intellect is a power of the soul which is the form of the body, although that power itself which is the intellect is not the act of any organ "since the operation of the body does not at all share in its operation," as Aristotle says,1 we should inquire by reason what must be thought of this.

And because, according to Aristotle's doctrine, it is necessary to consider the principles of acts from the acts, it seems that the first point to be considered is the very act proper to the intellect; and this is understanding. In this way we can have no argument more sound than that which Aristotle sets forth. He argues thus: "The soul is the first principle by which we live and understand; therefore it is a certain definable form or species"2 of some body.

And he relies on this argument to the extent that he calls it a demonstration; for at the beginning of the chapter he speaks thus: "Not only is it necessary to give a definition for an essence, as many expressions do, but also to show that its cause is in it and to prove it. Now the strength and the binding force of this demonstration are evident from the fact that whoever wishes to turn aside from this way, must hold something unreasonable.

For it is clear that this individual man understands; for we would never raise a question about the intellect unless we understood; and when we do raise a question about the intellect, we do not ask about any other principle than that by which we understand. Wherefore Aristotle says: "Now I mean the intellect by which the soul understands. Keeler notes, however, that in Aristotle's example cited in the last line of De Un. And this is evident through the reason that everything acts in so far as it is in act, but everything is in act through the form.

Whence it must be that that by which something first acts is the form. Averroes' explanation is disproved. Now if you should say that the principle of this act of understanding, a principle that we call the intellect, is not the form, you will have to find a way in which the action of that principle may be the action of this man.

This some persons have tried to state in different ways. One of these, Averroes,6 held that the principle of this kind of understanding, a principle that is called the possible intellect, is not the soul nor a part of the soul, except equivocally, but rather that it is a separate substance. He said7 that the understanding of that separate substance is my understanding or that person's understanding, in so far as that possible intellect is joined to me or to you through phantasms which are in me and in you.

He said that this is accomplished in the following way. Now the intelligible species, which becomes one with the possible intellect since it is its form and act, has two subjects: one, the phantasms themselves; the other, the possible intellect. So therefore the possible intellect is in contact with us through its form by means of the phantasms; and thus, as long as the possible intellect understands, this man understands. But that this is no explanation is evident for three reasons.

First of all, because such a contact of the intellect with man would not be from the beginning of man's generation, as Theophrastus says8 and as Aristotle implies in Book II of the Physics,9 where he says that the term of the natural philosopher's consideration of forms is the form according to which man is generated from man and the sun. Now it is clear that the term of the natural philosopher's consideration is the intellect.

II, 59; Q. VI, p. On Theophrastus, see De Un. Keeler notes that the same argument is used in Sum. II, 59, and that in Sum. II, 60, St. For the imagination ''is moved by sense in act,'' as is said in the book, De Anima. But secondly,11 because this conjoining would not be accord-to a single principle, but according to diverse principles. For it is clear that the intelligible species, in so far as it is in the phantasm is potentially understood; but it is in the possible intellect in so far as it is actually understood and abstracted from phantasms.

If, therefore, the intelligible species is not the form of the possible intellect except in so far as it is abstracted from phantasms, it follows that the possible intellect is not in contact with the phantasms through the intelligible species, but rather it is separated from them. Unless perhaps it be said that the possible intellect is in contact with phantasms as a mirror is in contact with the man whose appearance is reflected in the mirror.

But such a contact clearly does not suffice for the contact of the act. For it is clear that the action of the mirror, which is to represent, cannot on this account be attributed to the man. Whence neither can the action of the possible intellect be attributed, on account of the above-mentioned joining, to this man who is Socrates, in such a way that this man would understand.