Article 9 — Whether the soul is united to corporeal matter through a medium

Ninth, it is asked whether the soul is united to corporeal matter through a medium. (Parallel texts: ST I.76.6, 7; SCG II.71; In II Sent., d. 1, q. 2, a. 4, ad 3; Quodlibet I, q. 4, a. 1; Quodlibet XII, q. 6, a. 2; q. 7, a. 1; On Spiritual Creatures, a. 3; Commentary on Aristotle’s On the Soul, bk. 2, lect. 1; Commentary on Aristotle’s Metaphysics, bk. 8, lect. 5.)

Obj. 1: It seems that it is. For it is stated in the work The Spirit and the Soul that the soul has powers by which it is united to the body. (Pseudo-Augustine (Alcher of Clairvaux), The Spirit and the Soul, ch. 10 (PL 40:785–86); ch. 20 (PL 40:794).) But the powers of the soul are distinct from the soul’s essence. Therefore, the soul is united to the body through some medium. (Cf. ST I.76.6, obj. 3; On Spiritual Creatures, a. 3, obj. 6.)

Obj. 2: But it might be said that the soul is united through the medium of its powers to the body as the mover of the latter and not as its form. (Cf. Aquinas, In II Sent., d. 31, q. 2, a. 1, ad 1; SCG II.71.)

On the contrary, the soul is the form of the body inasmuch as it is an act but is a mover inasmuch as it is a principle of operation. And certainly a thing is a principle of operation inasmuch as it is an act, because a thing acts inasmuch as it is actual. (Cf. Aquinas, Commentary on Aristotle’s On Sense and What Is Sensed, tract. 1, ch. 9.) Hence, the soul is the form and mover of the body in the same respect. Consequently, no distinction is to be drawn between the soul as the mover of the body and as its form. (Cf. Aquinas, In II Sent., d. 31, q. 2, a. 1, ad 1; SCG II.71.)

Obj. 3: Further, inasmuch as the soul is the mover of the body, it is not united to the body accidentally, because then a being that is substantially one would not result from the union of soul and body. Therefore, the soul is united to the body substantially. But whatever is united to a thing substantially is united to it without a medium. Consequently, the soul is not united as a mover to the body through a medium.

Obj. 4: Further, the soul is united as a mover to the body inasmuch as it is the body’s principle of operation. However, the soul’s operations do not belong to the soul alone, but to the composite, as is pointed out in On the Soul 1, and thus there is no medium between the soul and the body so far as the soul’s operations are concerned. (Aristotle, On the Soul 1.4, 408b11–15.) Hence, the soul, inasmuch as it is the mover of the body, is not united to the body through a medium.

Obj. 5: Further, it seems that the soul, as a form, is united to the body through a medium. For a form is not united to any kind of matter but to one befitting it. (Cf. Aristotle, Metaphysics 8.4, 1044a27; Physics 2.2, 194b9; On the Soul 1.3, 407b13–16; 2.2, 414a25–27; Aquinas, Commentary on Aristotle’s On the Soul, bk. 1, lect. 8.) Now the matter of any particular form is prepared to receive that form through proper dispositions which are proper accidents of a thing, just as hot and dry are proper accidents of fire. (Cf. Aristotle, On Generation and Corruption 2.3, 330a30–b5; 331a5.) Therefore, a form is united to its matter through the medium of proper accidents. But the proper accidents of living things are the powers of their soul. Therefore, the soul, as a form, is united through the medium of its powers to the body. (Cf. ST I.76.6, ad 1.)

Obj. 6: Further, an animal is a thing that moves itself. But a thing that moves itself is divided into two parts, one of which is a mover, the other a thing moved, as is proved in Physics 8. (Aristotle, Physics 8.4, 254b15; 8.5, 257a33–258b9; cf. Aquinas, Commentary on Aristotle’s On the Soul, bk. 1, lect. 11.) Now the part causing movement is a soul; however, the moved part cannot be matter alone, because whatever is in potency only is not moved, as is said in Physics 5. (Aristotle, Physics 5.1, 225a20–23.) Hence, although heavy and light bodies have movement in themselves, they do not move themselves because they are divided only into matter and into form, which cannot be moved. It follows, then, that an animal is divided into a soul and into some part which is composed of matter and form. Consequently, the soul is united to corporeal matter by means of some form.

Obj. 7: Further, the proper matter of any form is given in the definition of that form. Now “a physical organic body potentially having life” is given in the definition of the soul inasmuch as it is the form of the body, as is evident in On the Soul 2. (Aristotle, On the Soul 2.1, 412a27–28; 412b5–6; cf. Aquinas, Commentary on Aristotle’s On the Soul, bk. 2, lect. 1.) Consequently, the soul is united to such a body as its proper matter. But “a physical organic body potentially having life” can exist as such only because of some form. Therefore, the soul is united to its matter through some form which first perfects its matter. (Cf. Aquinas, On Spiritual Creatures, a. 3, obj. 2; Commentary on Aristotle’s On the Soul, bk. 2, lect. 1.)

Obj. 8: Further, it is said, then the Lord God formed man from the dust of the ground and breathed into his nostrils the breath of life (Gen 2:7). Now the breath of life is the soul. Hence, some form exists in matter prior to its union with the body, and thus the soul is united to corporeal matter through the medium of some other form. (Cf. Aquinas, Quodlibet I, q. 4, a. 1, obj. 1.)

Obj. 9: Further, forms are united to matter so far as matter is in potency to them. But matter is first in potency to the forms of the elements rather than to other forms. (Aristotle, On Generation and Corruption 2.1, 329a25–35.) Consequently, the soul and other forms are united to matter only through the intermediary forms of the elements.

Obj. 10: Further, the body of a man and that of an animal are mixed bodies. But the forms of the elements must remain essentially in a mixed body, (Cf. Aristotle, On the Heavens 3.3, 302a16–17; Avicenna, Sufficientia (the Latin title for the section of the Book of Healing on natural science or physics), tract. 1, ch. 6; Metaphysics, bk. 8, ch. 2.) otherwise there would be a corruption of the elements and not a mixture. Therefore, the soul is united to matter through the medium of other forms.

Obj. 11: Further, the intellective soul as such is a form. But its act of understanding is accomplished with the aid of its other powers. Therefore, the soul, inasmuch as it is a form, is united to the body through the medium of these other powers.

Obj. 12: Further, the soul is not united to any sort of body, but to one proportioned to it. Therefore, there must be a proportion between the soul and the body, and thus the soul is united to the body by means of a proportion. (Cf. Aquinas, In II Sent., d. 1, q. 2, a. 4, ad 3; ST I.76.5, obj. 1; Commentary on Aristotle’s On the Soul, bk. 1, lect. 6.; Aristotle, On the Soul 2.3, 414a25–27; 2.1, 412b11–17; 1.3, 407b20–25.)

Obj. 13: Further, a thing operates in something remote through that which is closest to itself. But the powers of the soul are diffused throughout the whole body by the heart. Therefore, the heart is nearer to the soul than the other parts of the body, and thus the soul is united to the body by means of the heart. (Cf. Avicenna, De anima, part 5, ch. 8.)

Obj. 14: Further, a diversity of parts mutually related are present in the body. However, the soul is simple so far as its essence is concerned. Therefore, since a form is proportioned to the matter that is capable of being perfected by it, it seems that the soul is united first to one part of the body, and then to the other parts of the body through the intermediary of this first part.

Obj. 15: Further, the soul is superior to the body. But the inferior powers of the soul are united to the superior parts of the body, for the intellect requires the body only because of the imagination and the external senses from which it receives species. Therefore, conversely, the soul is united to the body through those things which are highest and simplest, as through spirits and humors.

Obj. 16: Further, that which when taken away destroys the unity among things united to one another is seen to be a medium between them. But the union of soul and body is dissolved when the spirits have been removed, the natural heat extinguished, and the basic moisture exhausted. (Cf. ST I.76.7, obj. 2.) Therefore, these things are means between the soul and the body.

Obj. 17: Further, as a soul is naturally united to a body, so is this soul united to this body. But this body is this body through the fact that it possesses certain terminated dimensions. (Cf. Aquinas, On Being and Essence, ch. 2; In I Sent., d. 25, q. 1, a. 1, ad 2; Commentary on Boethius’s De Trinitate, q. 4, a. 2, resp.; Avicenna, Sufficientia, tract. 1, ch. 2; Metaphysics, bk. 2, ch. 3.) Therefore, the soul is united to the body by the medium of terminated dimensions.

Obj. 18: Further, things which differ from one another are united only through a medium. But the soul and the human body are seen to differ from each other to the greatest degree because one of them is incorporeal and simple, the other corporeal and particularly complex. (Cf. Aquinas, In II Sent., d. 1, q. 2, a. 4, obj. 3; ST I.76.7, obj. 3.) Therefore, the soul is united to the body only through a medium.

Obj. 19: Further, the human soul is similar in intellectual nature to the separate substances which move the heavenly bodies. Now these are seen to be related to one another as movers and things capable of being moved. Consequently, it seems that the human body, which is moved by the soul, has within itself something of the nature of a heavenly body, and that the soul is united to the body by means of this.

On the contrary, the Philosopher says in Metaphysics 8 that a form is united to its matter directly. (Aristotle, Metaphysics 8.6, 1045b16–22.) Now the soul is united as a form to the body. Therefore, it is united to the body directly.

I answer that among all principles the act of existing is that which most immediately and intimately belongs to things, as is pointed out in the Book of Causes. (The Book of Causes, proposition 4.) Hence, the form which gives matter its act of existing must be understood to come to matter prior to anything else, and to be present in it more immediately than anything else, because matter receives its act of existing from a form. Moreover, it is proper to a substantial form to give matter its act of existing pure and simple, because it is through its form that a thing is the very thing that it is. For a thing is not given an act of existing pure and simple through accidental forms, but only a relative one such as to be large or colored, and so on. Therefore, if there is a form which does not give to matter its act of existing pure and simple but comes to matter already possessing an act of existing through some form, such a form will not be a substantial one. (Cf. Aquinas, In I Sent., d. 8, q. 5, a. 2, resp.; d. 17, q. 1, a. 2, resp.; d. 15, q. 5, a. 3, resp.; In II Sent., d. 18, q. 1, a. 2, resp.; SCG II.58; ST I.76.6; Commentary on Aristotle’s On the Soul, bk. 2, lect. 1; Compendium theologiae, bk. 1, ch. 90; On Spiritual Creatures, a. 3.)

From this it is obvious that an intermediary substantial form cannot intervene between a substantial form and matter, as some wished to maintain. For these men held that there exists in matter an order of diverse forms, one of which is arranged under another in accordance with the order of genera; as if one were to say, for instance, that matter is given the act of existing of a substance through one form; the act of existing of a body through another; the act of existing of a living body through still another; and so on. But if this position is adopted, only the first form which gives a thing its act of existing as a substance would be a substantial one. The other forms, indeed, would all be accidental ones, because it is a thing’s substantial form that makes it be a substance, as we have already shown. (Above: in this same response; see also q. 1; q. 6, resp.; Quodlibet XI, q. 5, a. 1, resp.) Therefore, it is necessary to say that a thing has substantiality, exists in the ultimate species, (Cf. Avicenna, Metaphysics, bk. 5, ch. 4.) under which there are no other species, and in all intermediate genera, through one and the same form.

Now the forms of natural things are like numbers whose species change when a unit is added or subtracted, as is pointed out in Metaphysics 8. (Aristotle, Metaphysics 8.3, 1043b33–1044a2; Aquinas, Commentary on Aristotle’s On the Soul, bk. 2, lect. 5; ST I.47.2; On Spiritual Creatures, a. 3, resp.; Quodlibet I, q. 4, a. 1.) It follows, therefore, that the diversity of natural forms, in accordance with which matter is constituted in diverse species, is to be understood as resulting from this fact, that one adds a perfection over and above another. (Cf. Aquinas, Compendium theologiae, bk. 1, ch. 92.) For example, one form gives matter corporeal existence only. This must be below the grade of animal forms, because matter is in potency only to corporeal forms. For those things which are incorporeal are immaterial, as was shown in the preceding question. (Above: q. 7, resp.; q. 6, resp.) A second, more perfect, form gives matter vital existence in addition to corporeal existence. Another, still higher, form confers on it sensory existence in addition to vital and corporeal existence; and so on successively.

Therefore, a more perfect form, constituting with matter a composite being in the perfection of an inferior grade, must be considered as matter with respect to a higher perfection; and so on up the scale. (Cf. Aristotle, Metaphysics 8.4, 1044a21–22; Aquinas, Compendium theologiae, bk. 1, ch. 92; Commentary on Aristotle’s On the Soul, bk. 2, lect. 1.) For instance, prime matter, so far as it now exists in a corporeal mode, is matter with respect to the higher perfection of life. And so, body is the genus of living body, and animated or living is the specific difference. For genus is derived from matter, and difference from form. (Cf. Aquinas, On Being and Essence, ch. 2.) Thus, in a certain way, one and the same form actualizing matter in a lower grade of perfection is midway between matter and that same form actualizing matter in a superior grade.

But matter, so far as it is understood to have substantial existence as a perfection of an inferior grade, can, therefore, be regarded as the subject of accidents. For a substance in that inferior grade of perfection must have a proper accident which necessarily inheres in it. Likewise, from the fact that matter has corporeal existence through forms, it immediately follows that there are dimensions in matter whereby it is understood to be divisible into different parts, so that it can receive different forms corresponding to its different parts. (Cf. Aquinas, On Truth, q. 5, a. 9, ad 6; see also De natura materiae, ch. 2, by an unknown author, although it has been attributed to Aquinas.) Furthermore, from the fact that matter is known to have a certain substantial mode of existing, matter can be understood to receive accidents by which it is disposed to a higher perfection, so far as it is fittingly disposed to receive that higher perfection. Moreover, dispositions of this kind are understood to exist in matter prior to the form, inasmuch as they are given existence in matter by an agent, although there are some improper accidents of the form that are caused in the matter only by the form itself. Hence, such accidents are not understood to exist as dispositions in matter prior to the form; rather, the form is understood to be prior to the proper accidents as a cause is to its effects.

Consequently, since the soul is a substantial form, because it places man in a determinate species of substance, no other substantial form intervenes between the soul and prime matter. But man is perfected in different grades of perfection by the rational soul itself, so that he is a body, a living body, and a rational animal. (Cf. Aquinas, On the Power of God, q. 3, a. 11, ad 2; ST I.76.6, ad 1; Commentary on Aristotle’s On the Soul, bk. 2, lect. 1; On Spiritual Creatures, a. 3, resp.) However, matter—being understood to receive, from the rational soul itself, perfections of an inferior grade, for instance, that of being a body, a living body, and an animal—must also be understood to have, at the same time, appropriate dispositions so that it may be matter befitting a human soul, inasmuch as the soul gives the body its ultimate perfection. So, therefore, the soul, inasmuch as it is the form which gives the act of existing absolutely, does not have any intermediary between itself and prime matter.

But because the same form which gives matter its act of existing is also a principle of operation, for a thing acts so far as it is in act, (Cf. Aquinas, Commentary on Aristotle’s On the Soul, bk. 3, lect. 1.) then the soul, like any other form, must be a principle of operation. (Cf. Averroes, Commentary on Aristotle’s On the Soul, bk. 3, comm. 18; Aquinas, Compendium theologiae, bk. 1, ch. 96; SCG II.20; III.88.) But it must be considered that a gradation of forms in the order of operation corresponds to the gradation of forms in the order of existence, for an operation is an act of an agent in act. Therefore, the greater perfection a form possesses with respect to conferring the act of existing, so much the greater is its power of operating. Hence, more perfect forms have a greater number of operations and more diverse ones than less perfect forms. And so it is that a diversity of accidents suffices for a diversity of operations in the case of less perfect things. But in the case of more perfect things, a diversity of parts is required as well, and the greater the diversity of parts, the more perfect the form will be. For we see that diverse operations are proper to fire because its accidents differ, for example, to rise upward in virtue of its lightness, to heat in virtue of its heat, and so on. (Cf. Aristotle, On the Heavens 1.2, 269a25–26; On Generation and Corruption 2.3, 330b1–5; Aquinas, Commentary on Aristotle’s On the Heavens, bk. 1, lect. 3, n. 29; lect. 5, n. 55; bk. 2, lect. 4, n. 337; lect. 10, n. 387.) However, any one of these operations belongs to any part of fire. But in animate bodies which have nobler forms, different operations are allotted to different parts; for instance, in plants there is one operation performed by the roots, another by the trunk, and still another by the branches. And the more perfect living bodies are, so much the more diverse must their parts be in view of their greater perfection. (Cf. Aquinas, Commentary on Aristotle’s On the Soul, bk. 1, lect. 14.) Therefore, since the rational soul is the most perfect of natural forms, there is found in man the greatest diversity of parts because of his different operations. Furthermore, the one soul performing these operations confers substantial existence in a manner befitting the operations of the parts themselves. An indication of this fact is that, when the soul ceases to animate the body, neither flesh nor eye remains except in an equivocal sense. (Cf. SCG II.69; ST I.76.8; III.50.5 ad 1; Commentary on Aristotle’s On the Soul, bk. 2, lect. 1; On Spiritual Creatures, a. 4.)

But since there must be an order of instruments in keeping with the order of operations, and since there is a natural precedence among the different operations which flow from the soul, one part of the body must be moved to perform its operations by another part. Thus, a medium intervenes between the whole body and the soul as the mover and principle of its operations. For after a certain primary mediating part of the body has been moved, that part moves the other parts to perform their operations. (Cf. Aquinas, Commentary on Aristotle’s On the Soul, bk. 2, lect. 1.) So it is that the soul, by means of the heart, moves the other members of the body to perform their vital operations. (See above: q. 8, resp.; Aquinas, Commentary on Aristotle’s On the Soul, bk. 2, lect. 18.) But since the soul gives to the body its act of existing, it immediately gives to all parts of the body their substantial and specific mode of existing. And this is what many assert, namely, that as a form the soul is united to the body without an intermediary, but that as a mover it is united to the body through an intermediary. (Cf. SCG II.71; On Spiritual Creatures, a. 3; Commentary on Aristotle’s On the Soul, bk. 2, lect. 1.)

Moreover, this view is in keeping with the position of Aristotle, who maintains that the soul is the substantial form of the body. (Aristotle, On the Soul 2.1, 412a20–22.) However, some who, following Plato’s theory, hold that the soul is united to the body as one substance is to another, had to posit means through which the soul is united to the body. (Cf. Aquinas, In II Sent., d. 1, q. 2, a. 4, ad 3; Nemesius, On the Nature of Man, cc. 1–2.) For diverse and disparate substances are unified only if something exists to unite them. For this reason, some held that there is a certain spirit and humor existing as a medium between soul and body, (See above: q. 8, resp.; On Evil, q. 16, a. 1, ad 5.) other posited light, (Cf. Augustine, On the Literal Interpretation of Genesis, bk. 7, ch. 15 (CSEL 28.1:213; PL 34:363); see above: q. 6, resp.; Aquinas, Commentary on Aristotle’s On the Soul, bk. 2, lect. 14; ST I.66.3, resp.; I.68.4, resp.) still others, the powers of the soul, or something else of this sort. But none of these are necessary if the soul is the form of the body, because anything whatever, inasmuch as it is a being, is one. (Cf. Aquinas, In II Sent., d. 1, q. 2, a. 4, resp.; ST I.76.7; above: q. 6, resp.) Hence, a form is united to prime matter by virtue of itself and not by any other bond, because a form, by its very nature, gives to matter its act of existing. (Cf. Averroes, Commentary on Aristotle’s On the Soul, bk. 2, comm. 7.)

Reply Obj. 1: The powers of the soul are the qualities by which it operates. Therefore, they serve as intermediaries between the soul and the body inasmuch as the soul moves the body, but not inasmuch as it gives to the body its act of existing. Moreover, it must be understood that the work which is called The Spirit and the Soul is not a work of Augustine, and that its author is of the opinion that the soul is its powers. (Pseudo-Augustine (Alcher of Clairvaux), The Spirit and the Soul, ch. 13 (PL 40:788–89); On Spiritual Creatures, a. 3, ad 6; a. 11, ad 2.) Hence, the objection fails completely.

Reply Obj. 2: Although the soul is a form inasmuch as it is an act, and similarly is a mover inasmuch as it is an act, and thus is a form and a mover in one and the same respect, nevertheless the effect which it produces as a form differs from that which it produces as a mover. The distinction is made for this reason.

Reply Obj. 3: One being pure and simple does not result from the union of a mover and a thing moved inasmuch as they are mover and moved, but from the union of this mover that is the soul, inasmuch as the soul is the form of the body, and this mobile thing which is the body.

Reply Obj. 4: Nothing intervenes between the soul and any part of the body with respect to any operation of the soul which is an operation of the composite. However, there is one part of the body through which the soul first exercises its operation, which falls midway between the soul, so far as it is the principle of that operation, and all the other parts of the body which share in that operation.

Reply Obj. 5: The accidental dispositions which dispose matter properly for some form are not means absolutely between form and matter, but between form inasmuch as it bestows the highest perfection, and matter inasmuch as it is already perfected by some perfection of an inferior order. For matter by its very nature is first with respect to the lowest grade of perfection, because matter of itself is in potency to substantial corporeal existence and does not require any disposition to this. (Aristotle, Physics 2.1, 193a29–30; On Generation and Corruption 2.1, 329a33–35; cf. Aquinas, Commentary on Aristotle’s Physics, bk. 1, lect. 15, n. 131.) But matter, having this perfection already in existence, requires dispositions to a higher perfection. Moreover, it must be recognized that the powers of the soul are its proper accidents and do not exist without the soul. (Cf. Aquinas, In I Sent., d. 3, q. 4, a. 2, resp.; ST I.29.1, ad 3.) Therefore, inasmuch as they are its powers, they do not have the nature of a disposition in relation to the soul except so far as the powers of the inferior part of the soul are called dispositions in relation to the powers of the superior part, just as the powers of the vegetative soul are dispositions in relation to the sensitive soul, as can be seen from the preceding argument.

Reply Obj. 6: This argument concludes that the soul or the animal is divided into two parts, one of which is like a mobile thing, the other like a mover. (Cf. Aristotle, Physics 8.5, 257a33–258a5; Aquinas, Commentary on Aristotle’s On the Soul, bk. 1, lect. 6.) This, indeed, is true, but we must understand that the soul moves the body through knowledge and appetite. (Cf. Aristotle, On the Soul 1.3, 406b24–25; 3.10, 433a13.) Now knowledge and appetite in man are of two kinds. The first is that which belongs to the soul alone and which does not depend on a bodily organ. This belongs to the intellective part of the soul. The second is that which belongs to the composite. (Cf. Aquinas, Commentary on Aristotle’s On the Soul, bk. 1, lect. 10; bk. 2, lect. 5; bk. 3, lect. 8; bk. 3, lect. 9.) This belongs to the sensitive part of the soul.

Now whatever belongs to the intellective part moves the body only by means of that which belongs to the sensitive part. For when a movement has to do with some particular thing, the universal apprehension that belongs to the intellect causes movement only by means of something particular belonging to sense. Hence, when we divide a man or an animal into a part that causes movement and one that is moved, we do not divide them into a soul and a body exclusively, but into a soul and an animated body. For that part of the animated body whose operation it is to apprehend and to desire, moves the whole body. But if it be supposed that the intellective part moves the body directly, so that the part causing movement in man is the soul alone, then the answer will be in accordance with the preceding explanation. (Above: resp.) For the human soul will be a mover in virtue of what is supreme in itself, namely, its intellective part. Moreover, the moved part will not be prime matter alone, but prime matter inasmuch as it is given a corporeal and vital act of existing. Nor will it be moved by any other form than the soul. Hence, it will not be necessary to maintain that a substantial form acts as an intermediary between the soul and prime matter.

However, there is a certain movement in the animal that is not the result of apprehension and desire—that is, the movement of the heart, the movement also of growth and decay, and the movement of nutrition which is diffused throughout the whole body, and which the animal has in common with plants. Now with respect to this kind of movement, we must maintain that, as inferior forms are the principles of movement in natural bodies, so also is the soul the principle of movement in animal bodies. For the animal soul not only bestows what is proper to its nature as such but also gives those perfections which belong to a lower order of forms, as is evident from what has been said.

Hence, the Philosopher says in On the Soul 2 that the soul is the nature of this specific type of body. (Aristotle, On the Soul 2.2, 414a18–28; cf. On the Parts of Animals 1.1, 641a25–27; Aquinas, On the Motion of the Heart.) For this reason, the operations of the soul are divided into animal operations and natural operations. That is to say, those operations which proceed from the soul in keeping with its proper nature are called animal operations, whereas those which come from the soul inasmuch as it produces the effect of inferior natural forms are called natural operations.

According to this, therefore, it must be said that, as fire through its natural form has a natural movement whereby it tends upwards, so also any part of an animated body, in which there is found movement not resulting from apprehension, has this movement naturally through its soul. For as fire tends upward by nature, so also the blood is moved naturally to its proper and determinate place. Similarly, the heart is moved naturally by its proper movement, although the dissolution of spirits, made from the blood, by which the heart is expanded and contracted, cooperates in this activity, as Aristotle points out in the place where he treats of exhalation and inhalation. (Aristotle, On Respiration, ch. 21, 480a16–b30; 499b26; On the Parts of Animals 1.1, 642a31–b3; cf. Aquinas, Commentary on Aristotle’s On the Soul, bk. 3, lect. 9; On the Motion of the Heart; ST I-II.17.9.) Consequently, the first part of the body in which such movement is found is not a self-mover, but is moved naturally, just as fire is. However, this part moves another part, and thus the whole animal is a self-mover, because one part of it is a mover, and another is moved. (Cf. Aquinas, On the Motion of the Heart.)

Reply Obj. 7: A physical organic body is related to the soul as matter to form, not that it is such a body as a result of some other form, but because it has this nature through the soul, as was shown above. (Above: resp.; cf. Aristotle, On the Soul 2.1, 412b25–26.)

Reply Obj. 8: The eighth argument must be answered similarly. For the statement in Genesis, God formed man of dust from the ground, is not prior in time to the following, and breathed into his nostrils the breath of life (Gen 2:7) but is prior in the order of nature only.

Reply Obj. 9: Matter is in potency to forms with respect to a certain order, not that it receives different substantial forms in a certain order, but because it receives whatever is proper to a superior form only through the medium of what is proper to an inferior form, as was shown. (Above: resp.) In this way matter is understood to receive other forms by way of the forms of the elements.

Reply Obj. 10: The forms of the elements do not exist according to their very essence in a mixed body, although Avicenna maintained this, for they cannot exist in one and the same part of matter. (Cf. Avicenna, Sufficientia, tract. 1, ch. 6; Metaphysics, bk. 8, ch. 2; Aristotle, On the Heavens 3.3, 302a16–17.) However, if they were to exist in different parts of matter, there would not be a mixture with respect to the whole, as is the case in a true mixture, but there would be a mixture of the most insignificant kind, that is to say, one which appears to be a mixture to the senses. Again, to say that the forms of the elements may receive more and less, as Averroes does, (Averroes, Commentary on Aristotle’s On the Heavens, bk. 3, comm. 67.) is ridiculous, because they are substantial forms which cannot receive more and less. (Cf. Aquinas, Commentary on Boethius’s De Trinitate, q. 4, a. 3, ad 6.) Nor is there a medium between a substance and an accident as he imagined. Moreover, it must be said that the forms of the elements are not corrupted completely, but that they remain virtually, as Aristotle says. (Aristotle, On Generation and Corruption 1.10, 327b29–31; cf. Aquinas, On the Blend of the Elements.) And they are virtually present inasmuch as the proper accidents of the elements, in which the power of the elements is found, remain in some measure.

Reply Obj. 11: The intellective soul is the form of the body according to its very essence, but not according to its intellectual operation.

Reply Obj. 12: The proportion that exists between the soul and the body is in the things proportioned. Consequently, it does not necessarily have to be an intermediary between soul and body.

Reply Obj. 13: The heart is the first instrument through which the soul moves the other parts of the body. Therefore, as a mover, the soul is united to the other parts of the body through the medium of the heart. However, as a form, the soul is united to every part of the body essentially and directly.

Reply Obj. 14: Although the soul is a form in its entirety so far as its essence is concerned, yet it is many by its powers inasmuch as it is the principle of different operations. Furthermore, because a form perfects a matter not only with respect to its act of existing but also with respect to its operation, it is necessary that the parts of the body be perfected in different ways by the soul, even though it is a form in its entirety, and that each part be perfected in a way befitting its operation. For this reason, there must be an order among the parts of the body in accordance with the order among operations, as was explained. However, this order exists inasmuch as the operation of the body belongs to the soul as the mover of the body.

Reply Obj. 15: The inferior powers of the soul, so far as their operations are concerned, can be understood to unite the superior powers to the body inasmuch as the superior powers stand in need of the operations of the inferior powers which are exercised through the body. Similarly, the body, so far as operation and movement are concerned, is joined through its superior parts to the soul.

Reply Obj. 16: A form accrues to matter only when matter is properly disposed by fitting dispositions, and thus a form cannot remain in matter when the proper dispositions cease to exist. In this way, when the heat, natural humidity, and the like, are removed from the body, the union of soul and body is destroyed, because the body is disposed to receive the soul by means of these things. Hence, things of this kind intervene as dispositions between the soul and the body. The explanation of this was given above. (Above: ad 5.)

Reply Obj. 17: Dimensions can be considered to exist in matter only so far as matter is given substantial corporeal existence through a substantial form. In man this kind of existence is not bestowed by any other form than the soul, as has been explained. Consequently, these dimensions are not understood actually to precede the existence of the soul in matter absolutely, but relative to the highest grades of perfection, as was explained above. (Above: resp.)

Reply Obj. 18: The soul and the body do not differ from each other as things of different genera and species do, because neither of them exists in a genus or a species, but only the composite of which they are parts, as we have shown in the preceding questions. (Above: q. 1, ad 13; q. 2, ad 10.) However, the soul by its very essence is the form of the body giving it its act of existing. Hence, it is united to the body essentially and directly.

Reply Obj. 19: The human body has something in common with a heavenly body, not inasmuch as something characteristic of a heavenly body, such as light, intervenes as a medium between the soul and the body, but inasmuch as the human body is given a certain tempered combination lacking contrariety, as was shown in preceding questions. (Above: q. 8.)