Article 6 — Whether the soul is composed of matter and form

Sixth, it is asked whether the soul is composed of matter and form. (Parallel texts: ST I.50.2; I.75.5; On Being and Essence, ch. 5; In I Sent., d. 8, q. 5, a. 2; In II Sent., d. 3, q. 1, a. 1; d. 17, q. 1, a. 2; Commentary on Boethius’s De Trinitate, q. 5, a. 4, ad 4; Commentary on Boethius’s Hebdomads, lect. 2; SCG II.50–51; On the Power of God, q. 6, a. 6, ad 4; Quodlibet III, q. 8, a. 1; Quodlibet IX, q. 4, a. 1; On Spiritual Creatures, a. 1; a. 9, ad 9; On Separated Substances, ch. 7.)

Obj. 1: It seems that it is. For Boethius says, in his book On the Trinity, that a simple form cannot be a subject. (Boethius, On the Trinity, ch. 2 (PL 64:1250D); cf. Aquinas, In I Sent., d. 8, q. 5, a. 2, obj. 4; In II Sent., d. 3, q. 1, a. 1, obj. 6; ST I.50.2, obj. 2.) But the soul is the subject of sciences and virtues. Therefore, the soul is not a form in its entirety and, consequently, is composed of matter and form.

Obj. 2: Further, Boethius says, in Hebdomads, that whatever exists, can participate in something else; but the act of existing itself cannot participate in anything. (Boethius, Hebdomads, rule 4, line 35 (PL 64:1311B).) For a similar reason, subjects participate in something but forms do not; for example, a white thing can participate in something besides whiteness, but whiteness itself cannot participate in anything. Now the soul participates in something, namely, in those things by which it is informed. Therefore, the soul is not a form alone but is composed of matter and form.

Obj. 3: Further, if the soul is a form in its entirety and is in potency to something, it seems that its act of existing above all is its act, for the soul is not its own act of existing. But act will be the simplest thing belonging to a simple potency. Therefore, the soul could not be the subject of anything else than its own act of existing. However, it is evident that it is the subject of other things. Therefore, the soul is not a simple substance but is composed of matter and form.

Obj. 4: Further, accidents proceeding from the form belong to the entire species; (Aristotle, Metaphysics 5.30, 1025a30–32; cf. Aquinas, In I Sent., d. 3, q. 4, a. 2, resp.; Commentary on Aristotle’s Physics, bk. 2, lect. 1, n. 144.) however, those coming from matter belong to this or to that individual; for the form is the principle of the species, whereas matter is the principle of individuation. (Cf. SCG II.49.) Therefore, if the soul is a form alone, all of its accidents will belong to the entire species. This appears to be false, however, because music and grammar and things of this sort do not belong to the entire species. Therefore, the soul is not a form alone but is composed of matter and form.

Obj. 5: Further, a form is a principle of action, and matter, the principle of passion. (That is, being acted upon. Cf. Aristotle, On Generation and Corruption 2.9, 335b29–31.) Therefore, anything in which there is action and passion is composed of matter and form. But action and passion are found in the soul itself because the operation of the potential intellect consists in being-acted-upon, and for this reason the Philosopher says that to understand is to undergo something. (Aristotle, On the Soul 3.4, 429b32; 429a13–15.) The operation of the agent intellect, on the other hand, consists in acting, for it makes the potentially intelligible, actually intelligible, as is said in On the Soul. (Aristotle, On the Soul 3.5, 430a14–16.) Consequently, the soul is composed of form and matter. (Cf. Aquinas, On Spiritual Creatures, a. 1, obj. 16.)

Obj. 6: Further, matter must enter into the composition of anything in which the properties of matter are found to exist. But the properties of matter are present in the soul, namely, to be in potency, to receive, to be a subject, and other things of this kind. (Cf. Avicebron (Solomon Ibn Gabirol, 11th cent. AD), The Fountain of Life, tract. 4, n. 10; Aquinas, In II Sent., d. 3, q. 1, a. 1, obj. 3; d. 17, q. 1, a. 2, obj. 2; ST I.50.2, obj. 2; I.75.5, obj. 2.) Therefore, the soul is composed of matter and form.

Obj. 7: Further, agents and patients must have a common matter, as is shown in On Generation and Corruption 1. (Aristotle, On Generation and Corruption 1.5, 322b18–20; 1.7, 324a34–35; cf. On the Soul 3.4, 429b22–26; Aquinas, Commentary on Aristotle’s On the Soul, bk. 3, lect. 3.) Hence, anything that can be acted upon by something material possesses matter. (Cf. Aquinas, On Spiritual Creatures, a. 1, obj. 20.) But the soul can be acted upon by something material, namely, by the fire of hell, which is corporeal fire, as Augustine proves in City of God. (Augustine, City of God, bk. 21, ch. 10 (Corpus Christianorum Series Latina [CCSL] 48:775–76; PL 41:724–25).) Therefore, the soul possesses matter.

Obj. 8: Further, the action of an agent does not terminate in a form, but in a composite of matter and form, as is shown in Metaphysics 8. (Aristotle, Metaphysics 8.6, 1045b5; 7.8, 1033b16–19; cf. Aquinas, Commentary on Aristotle’s Metaphysics, bk. 7, lect. 7, nn. 1418–24.) But the action of one agent, namely, God, terminates in the soul. Therefore, the soul is composed of matter and form. (Cf. Aquinas, In II Sent., d. 17, q. 1, a. 2, obj. 4.)

Obj. 9: Further, whatever is a form in its entirety is at once a being and a unity and does not require anything to make it a being and a unity, as the Philosopher points out in Metaphysics. (Aristotle, Metaphysics 8.6, 1045a36–b7.) The soul, however, requires something which makes it a being and a unity, namely God, who creates it. Therefore, the soul is not a form in its entirety. (Cf. ST I.75.5, obj. 3; On Spiritual Creatures, a. 1, obj. 5.)

Obj. 10: Further, an agent is necessary in order that something may be reduced from potentiality to actuality. (Cf. Aristotle, Metaphysics 7.8, 1034a3–5; Aquinas, Commentary on Aristotle’s Physics, bk. 2, lect. 10, n. 240.) But to be brought from potentiality to actuality belongs only to those things in which there is matter and form. (Cf. Aristotle, Physics 1.7, 190b11; 190b20.) Therefore, if the soul is not composed of matter and form, it does not require an efficient cause, which is clearly false.

Obj. 11: Further, Alexander says, in the book De intellectu, (Alexander of Aphrodisias, On the Intellect, 2.2. The De intellectu (Gk. Περὶ νοῦ) is itself a section of the Supplement to the Book On the Soul or De anima libri mantissa.) that the soul has a hylic intellect. (Gk. νοῦς ὑλικός.) Now “hyle” means prime matter. Therefore, the soul contains prime matter as a constituent part.

Obj. 12: Further, whatever exists is either pure act, pure potency, or is composed of potency and act. However, the soul is not pure act, because this is characteristic of God alone; (Cf. ST I.50.2, obj. 3.) nor is the soul pure potentiality, for in that case it would not differ from prime matter. Hence, the soul is composed of potency and act, and consequently is not a form in its entirety, because a form is an act. (Cf. Aquinas, In II Sent., d. 3, q. 1, a. 1, obj. 4; On Spiritual Creatures, a. 1, obj. 17.)

Obj. 13: Further, whatever is individuated, is individuated by matter. But the soul is not individuated by the matter in which it exists, that is, by the body, because when the body corrupted, the individuation of the soul would cease. (Cf. Aquinas, In I Sent., d. 8, q. 5, a. 2, obj. 6.) Therefore, the soul is individuated by matter which enters into its constitution and thus contains matter as an integral part.

Obj. 14: Further, an agent and a patient must have something in common, as is shown in On Generation and Corruption 1. (Aristotle, On Generation and Corruption 1.7, 323b31–33; 324a34.) But the soul is acted upon by sensible things which are material; nor can it be said that the substance of the sensitive soul differs from that of the intellective. Consequently, the soul has something in common with material things; and thus, it seems that it contains matter.

Obj. 15: Further, since the soul is not simpler than an angel, it must belong to a genus as a species of that genus, for this is proper to an angel. But whatever belongs to a genus as one of its species seems to be composed of matter and form, for a genus has the character of matter, and a specific difference has the character of form. (Cf. Aristotle, Metaphysics 8.2, 1043a19–20; 8.3, 1043a30–32; Avicenna, Metaphysics, bk. 5, ch. 5; Boethius, On Division (PL 64:879); Aquinas, In II Sent., d. 3, q. 1, a. 5, obj. 4; On Being and Essence, ch. 2; ST 1.50.2, obj. 1; Quodlibet IX, q. 4, a. 1, obj. 3; On Spiritual Creatures, a. 1, obj. 24.) Therefore, the soul is composed of matter and form.

Obj. 16: Further, a form common to several individuals is multiplied among these individuals as a result of material division. But intellectuality is a form which is common not only to the souls of men, but to the angels as well. Therefore, there must be some matter in the angels and in human souls, through whose division a form of this kind is multiplied among many individuals.

Obj. 17: Further, whatever is moved contains matter. But the soul is moved, for Augustine shows in this way that the nature of the soul is not divine, because it is subject to change. (Rather: Alcher of Clairvaux, The Spirit and the Soul, ch. 40 (PL 40:809–10); cf. Augustine, On the Literal Interpretation of Genesis, bk. 7, ch. 2, para. 3 (CSEL 28.1:202; PL 34:357); City of God, bk. 12, ch. 8 (CCSL 48:362–63; PL 41:355).) Therefore, the soul is composed of matter and form. (Cf. Aquinas, On Spiritual Creatures, a. 1, obj. 3; In II Sent., d. 17, q. 1, a. 2, obj. 3.)

On the contrary, everything composed of matter and form has a form. Therefore, if the soul is composed of matter and form, the soul itself has a form. But the soul is a form. Therefore, a form has a form; but this is evidently impossible because it would result in an infinite regression.

I answer that there are different opinions about this question. Some say that the soul and, indeed, every substance with the exception of God, is composed of matter and form. The first to maintain this position is Avicebron, the author of The Fountain of Life. (Avicebron, The Fountain of Life, bk. 1, ch. 5; bk. 2, ch. 24; bk. 4, cc. 1, 5; bk. 5, ch. 12.) The reason for this position, which is also mentioned in one of the objections, (Above: obj. 6.) is this: that matter is found wherever the properties of matter exist. Wherefore, since the properties of matter are found in the soul, namely, to receive, to be in potency, and other things of this kind, Avicebron judged there must be matter in the soul. But this argument is silly, and the position itself is impossible.

Now the weakness of this argument becomes apparent if we consider that to receive, to be a subject, and other things of this sort, are not found in the soul and in prime matter in the same specific way. (Cf. Aristotle, On the Soul 2.5, 417b1–17.) For prime matter is actuated by means of change and motion, and since every change and motion may be reduced to local motion, as the primary and most universal type of motion, as is proved in Physics 8, it follows that matter is present only in those things in which there is potency to place. (Aristotle, Physics 8.7, 260a27–261a27; Aquinas, Commentary on Aristotle’s Physics, bk. 8, lect. 14.)

Moreover, things of this kind, which are circumscribed by place alone, are corporeal. (Cf. Aristotle, Physics 4.1, 209a4–6.) Hence, in accordance with the way in which the philosophers have spoken about matter, matter is present only in corporeal things; unless, of course, someone wishes to employ matter in an equivocal sense. (Cf. Averroes, Commentary on Aristotle’s On the Soul, bk. 3, comm. 14; Aquinas, In II Sent., d. 3, q. 1, a. 1, resp.; On Being and Essence, ch. 4; On Spiritual Creatures, a. 1.) The soul, however, does not receive something by means of motion and change, but, on the contrary, by being separated from motion and from movable things. Accordingly, it is said in Physics 7 that the soul becomes cognitive and possesses prudence when at rest. (Aristotle, Physics 7.3, 247b10; 247b23–24.) Wherefore the Philosopher also states in On the Soul that understanding is referred to as a passion but is a passion of a different nature from that present in corporeal things. (Aristotle, On the Soul 3.4, 429a29–30.) Therefore, if anyone wishes to conclude that the soul is composed of matter because it is receptive or is acted upon, he is clearly deceived by an equivocation. Consequently, it is evident that the aforesaid argument is foolish.

Moreover, it can be shown in several ways that this position is impossible. First, for this reason, that when a form accrues to matter, it constitutes a species. Therefore, if the soul is composed of matter and form, a certain species will be established in the natural order as a result of the union itself of the form and matter of the soul. However, a thing which possesses a specific nature in its own right is not united to some other thing in order to constitute a species, unless each is corrupted in some manner, just as, for example, the elements are united in order to constitute the species of the mixed bodies. (Cf. Aristotle, On Generation and Corruption 2.7, 334b17–30; 1.10, 327b29–31; Aquinas, On the Blend of the Elements (De mixtione elementorum).) The soul, therefore, is not united to the body in order to constitute the human species, but the complete human species is comprised of the soul alone. This is clearly false, for if the body does not belong to the human species, it is joined to the soul in an accidental way.

Moreover, it cannot be said, according to this, that the hand is not composed of matter and form because it does not have a complete species of its own, but is a part of a species; for it is evident that the matter of the hand is not perfected separately by its own form, but that there is one form which perfects at the same time the matter of the whole body and that of all its parts. This could not be said of the soul if it were composed of matter and form. For in that case, the matter of the soul would first have to be perfected in the order of nature by its own form, and the body in turn perfected by the soul; unless, perhaps, someone might care to say that the soul’s matter is some part of corporeal matter, which is utterly absurd.

The position of Avicebron is also shown to be impossible for this reason, that in everything composed of matter and form, matter occupies the position of that which receives existence, and not that by which something exists; for this is peculiar to the form alone. Therefore, if the soul is composed of matter and form, it is impossible for the entire soul to be the formal principle which gives to the body its act of existing. The whole soul, therefore, will not be the form of the body, but only a part of the soul will be so. The soul, however, is certainly that entity which is the form of the body. Therefore, the soul is not that thing which was considered to be a composite of matter and form, but the form of it alone. (Cf. Aquinas, ST I.76.1, resp.)

This position is also seen to be impossible for another reason. For if the soul is composed of matter and form, and the body as well, each of them will have its unity in virtue of itself, and then it will be necessary to admit that some third entity exists which unites the soul to the body. Indeed, some of the adherents of the aforesaid position do maintain this. For they say that a soul is united to its body by the instrumentality of light, the vegetative soul by the mediating light of the sidereal heaven, the sensitive soul by the mediating light of the crystalline heaven, and the rational soul by the mediating light of the empyrean heaven. These explanations are entirely fictitious, because the soul must be united to the body without any intermediary, just as act is to potency, as is shown in Metaphysics 8. (Aristotle, Metaphysics 8.6, 1045b7–22; cf. Averroes, Commentary on Aristotle’s Metaphysics, bk. 8, comm. 16.) It becomes evident, then, that the soul cannot be composed of matter and form.

However, act and potency are not excluded from the soul, for potency and act are found not only in immovable things, but in movable things as well; and they are more common here, as the Philosopher points out in Metaphysics 9, because matter itself may not exist in immovable things. (Aristotle, Metaphysics 9.6, 1048a25–30; 8.5, 1044b26; Aquinas, Commentary on Aristotle’s Metaphysics, bk. 9, lect. 5.)

Now the manner in which act and potency are found in the soul must be discovered by proceeding from material things to immaterial ones. (Cf. Aquinas, On Spiritual Creatures, a. 1, resp.) For we observe three things in substances composed of matter and form, namely, matter, form, and the act of existing itself, the principle of which is the form; for matter receives an act of existing because it receives a form. (Cf. Averroes, Commentary on Aristotle’s Metaphysics, bk. 9, comm. 16; Aquinas, On the Principles of Nature, ch. 1; On Being and Essence, ch. 4.) Therefore, a thing’s act of existing is the natural effect of the form itself of that thing.

However, the form is not identical with its own act of existing, because the form is the principle of that act of existing. And although matter receives its act of existing only through some form, yet a form as such does not stand in need of matter in order to exist, because the act of existing is the natural effect of the form itself. However, a form requires matter in order to exist when it is a form of that specific type which does not subsist of itself. (Cf. Aquinas, On Being and Essence, ch. 4.)

Consequently, a form having its act of existing in itself is not prevented in any way from existing apart from matter, and the act of existing is found in a form of this kind. For the very essence of a form is related to its act of existing as a potency is to its proper act. It is in this way, then, that both potency and act are found in forms which subsist of themselves, inasmuch as the act of existing itself is the act of a subsisting form which is not its own act of existing. (Cf. Aquinas, On Being and Essence, ch. 4; ST I.75.5, ad 4.)

Moreover, if there is a thing which is its own act of existing, and this is proper to God alone, it does not contain potency and act but is pure act. (Cf. Aquinas, On Being and Essence, ch. 4.) It is for this reason that Boethius says in his Hebdomads that in the beings which are beneath God in perfection, the act of existing and quiddity are really distinct; (Boethius, Hebdomads, rules 7–8, lines 45–47 (PL 64:1311B); cf. Aquinas, On Being and Essence, ch. 4.) or as some say, that which is and that by which it is differ from each other. (Alexander of Hales (ca. 1185–1245 AD), Gloss on II Sent., d. 3, n. 7; Albert the Great, Commentary on Sentences II, d. 2E, a. 2, resp.) For the act of existing itself of a thing is that by which a thing exists; just as running is that by which someone runs. Consequently, since the soul is a certain form which subsists of itself, it can be composed of act and potency, that is, of an act of existing and an essence, but not of form and matter. (Cf. SCG II.54; Quodlibet IX, q. 4, a. 1.)

Reply Obj. 1: Boethius is speaking here of that form which is absolutely simple, namely, of the divine essence itself, which cannot be a subject in any way whatever because it contains no potency, but is pure act. However, other simple forms such as the angels and the human soul, even though they are subsisting beings, can, nevertheless, be subjects inasmuch as they possess some degree of potentiality which enables them to receive new perfection.

Reply Obj. 2: The act of existing itself is the highest act in which all things are capable of participating, but the act of existing itself does not participate in anything. Therefore, if there is a being which is itself a subsisting act of existing, just as we speak of God, we say that it does not participate in anything. However, this is not true of other subsisting forms which necessarily participate in the act of existing itself, and which are related to it as potency is to act; and thus, since these forms are in potentiality in some measure, they can participate in something else.

Reply Obj. 3: Not only is a form related to its act of existing as potency is to act, but, indeed, nothing prevents one from being related to another as potency is to act, just as the transparent medium is related to light, and light in turn to color. (Cf. Aquinas, Commentary on Aristotle’s On the Soul, bk. 2, lect. 14.) Hence, if transparency were a separate form subsisting in virtue of its own nature, it would be receptive not only of an act of existing, but of light as well. Similarly, nothing prevents subsisting forms like the angels and the soul from receiving not only the act of existing itself, but other perfections as well. However, the more perfect subsisting forms of this kind are, the less do they participate in their perfection, seeing that they have more of that perfection in the very principles of their nature.

Reply Obj. 4: Although human souls are forms in their entirety, nevertheless they are forms individuated in bodies, and are multiplied numerically because of the multiplication of bodies. Consequently, nothing prevents certain accidents which do not belong to the entire species from belonging to these forms inasmuch as they are individuated.

Reply Obj. 5: The sort of passion which is in the soul, and which is attributed to the potential intellect, does not belong to the same genus as the passions attributed to matter; for in these two cases matter is spoken of equivocally, as is evident from what the Philosopher says in On the Soul 3, because the passion of the potential intellect consists in a reception inasmuch as it receives something immaterially. (Aristotle, On the Soul 3.4, 429a29–b4; 430a3; 2.5, 417b2; Aquinas, Commentary on Aristotle’s On the Soul, bk. 2, lect. 11.) In like manner, the action of the agent intellect is not of the same mode as the action of natural forms, for the action of the agent intellect consists in abstracting forms from matter, whereas the action of natural agents consists in impressing forms on matter. Consequently, it does not follow from the kind of action and passion present in the soul that the soul is composed of matter and form.

Reply Obj. 6: To receive, to be a subject, and other things of this kind, are proper to the soul in a different way from the way they are to prime matter. Therefore, it does not follow that the properties of matter are found in the soul.

Reply Obj. 7: Although the fire of hell, by which the soul is acted upon, is material and corporeal, nevertheless the soul is not acted upon by it in a material way, as material bodies themselves are, but undergoes a spiritual affliction by means of it, inasmuch as it is the instrument of the judgment of divine justice. (Cf. Aquinas, Quodlibet VIII, q. 8, a. 1; On Truth, q. 26, a. 1, resp., ad 1.)

Reply Obj. 8: The action of a generator terminates in something composed of matter and form because a natural generator only produces something from matter; creative activity, however, does not depend upon matter. (Cf. Aquinas, On the Power of God, q. 3, a. 1; SCG II.16; ST I.45.2, ad 2.) Consequently, creative activity does not necessarily have to terminate in a composite of matter and form.

Reply Obj. 9: Those things which are subsisting forms, in that each is a unity and a being, do not require a formal cause, because they themselves are forms. However, they do require an external cause which gives them existence.

Reply Obj. 10: An agent, by its motion, brings something from potentiality to act. However, an agent that acts without any motion does not bring something from potentiality to actuality but gives actual existence to what by nature is potentially existing. (Cf. ST I.75.6, ad 2.) Creating is action of this kind.

Reply Obj. 11: The hylic intellect, that is, the material intellect, is the name which some men give to the potential intellect, not because it is a material form, but because it bears some likeness to matter inasmuch as it is in potency to intelligible forms, as matter is to sensible forms. (Cf. Aquinas, On the Unity of the Intellect, ch. 1.)

Reply Obj. 12: Although the soul is neither pure act nor pure potency, yet it does not follow that it is composed of matter and form, as was shown above. (Above: resp.)

Reply Obj. 13: The soul is not individuated by any matter of which it is composed, but by reason of its relationship to the matter in which it exists. How this is possible was shown in the preceding questions. (Aquinas, On Spiritual Creatures, aa. 2, 8; cf. On Being and Essence, ch. 5; On the Power of God, q. 3, a. 10.)

Reply Obj. 14: The sensitive soul is not acted upon by sensible things, but the soul conjointly with the body; for sensing, which is to undergo something, does not belong to the soul alone, but to the animated organ. (Cf. Aquinas, Commentary on Aristotle’s On the Soul, bk. 2, lect. 13; bk. 2, lect. 25; bk. 3, lect. 1.)

Reply Obj. 15: The soul does not belong properly to a genus as a species thereof, but as a part of the human species. (Cf. ST I.75.7, ad 2.) Therefore, it does not follow that it is composed of matter and form.

Reply Obj. 16: Intelligibility does not belong to many beings as though it were one specific form divided among many because of a division of matter, for it is a spiritual and immaterial form; rather, it is diversified because of a diversity of forms, whether the forms be different in species, like the soul of a man and an angel, or different in number only, like the souls of different men.

Reply Obj. 17: The soul and an angel are called changeable spirits inasmuch as they can be changed by choice—which change, indeed, is from one operation to another. (Cf. Aristotle, Nicomachean Ethics 3.3, 1113a10; Aquinas, Commentary on the Nicomachean Ethics, bk. 3, lect. 9; In II Sent., d. 24, q. 1, a. 2, obj. 4; In IV Sent., d. 13, q. 2, a. 1, resp.; ST I.82.1, ad 3.) Matter is not required for this kind of change, but only for natural changes, which are changes from one form to another, or from one place to another.