Summa Theologica, Part I · Aquinas Thomas
QUESTION 75
OF MAN WHO IS COMPOSED OF A SPIRITUAL AND A CORPOREAL SUBSTANCE: AND IN THE FIRST PLACE, CONCERNING WHAT BELONGS TO THE ESSENCE OF THE SOUL (In Seven Articles) Having treated of the spiritual and of the corporeal creature, we now proceed to treat of man, who is composed of a spiritual and corporeal substance. We shall treat first of the nature of man, and secondly of his origin. Now the theologian considers the nature of man in relation to the soul; but not in relation to the body, except in so far as the body has relation to the soul. Hence the first object of our consideration will be the soul. And since Dionysius (Ang. Hier. xi) says that three things are to be found in spiritual substances--essence, power, and operation--we shall treat first of what belongs to the essence of the soul; secondly, of what belongs to its power; thirdly, of what belongs to its operation. Concerning the first, two points have to be considered; the first is the nature of the soul considered in itself; the second is the union of the soul with the body. Under the first head there are seven points of inquiry. (1) Whether the soul is a body? (2) Whether the human soul is a subsistence? (3) Whether the souls of brute animals are subsistent?
(4) Whether the soul is man, or is man composed of soul and body? (5) Whether the soul is composed of matter and form? (6) Whether the soul is incorruptible? (7) Whether the soul is of the same species as an angel? _______________________ FIRST ARTICLE [I, Q. 75, Art. 1] Whether the Soul Is a Body? Objection 1: It would seem that the soul is a body. For the soul is the moving principle of the body. Nor does it move unless moved. First, because seemingly nothing can move unless it is itself moved, since nothing gives what it has not; for instance, what is not hot does not give heat. Secondly, because if there be anything that moves and is not moved, it must be the cause of eternal, unchanging movement, as we find proved Phys. viii, 6; and this does not appear to be the case in the movement of an animal, which is caused by the soul. Therefore the soul is a mover moved. But every mover moved is a body. Therefore the soul is a body. Obj. 2: Further, all knowledge is caused by means of a likeness. But there can be no likeness of a body to an incorporeal thing. If, therefore, the soul were not a body, it could not have knowledge of corporeal things.
Obj. 3: Further, between the mover and the moved there must be contact. But contact is only between bodies. Since, therefore, the soul moves the body, it seems that the soul must be a body. _On the contrary,_ Augustine says (De Trin. vi, 6) that the soul "is simple in comparison with the body, inasmuch as it does not occupy space by its bulk." _I answer that,_ To seek the nature of the soul, we must premise that the soul is defined as the first principle of life of those things which live: for we call living things "animate," [*i.e. having a soul] and those things which have no life, "inanimate." Now life is shown principally by two actions, knowledge and movement. The philosophers of old, not being able to rise above their imagination, supposed that the principle of these actions was something corporeal: for they asserted that only bodies were real things; and that what is not corporeal is nothing: hence they maintained that the soul is something corporeal. This opinion can be proved to be false in many ways; but we shall make use of only one proof, based on universal and certain principles, which shows clearly that the soul is not a body.
It is manifest that not every principle of vital action is a soul, for then the eye would be a soul, as it is a principle of vision; and the same might be applied to the other instruments of the soul: but it is the _first_ principle of life, which we call the soul. Now, though a body may be a principle of life, as the heart is a principle of life in an animal, yet nothing corporeal can be the first principle of life. For it is clear that to be a principle of life, or to be a living thing, does not belong to a body as such; since, if that were the case, every body would be a living thing, or a principle of life. Therefore a body is competent to be a living thing or even a principle of life, as "such" a body. Now that it is actually such a body, it owes to some principle which is called its act. Therefore the soul, which is the first principle of life, is not a body, but the act of a body; thus heat, which is the principle of calefaction, is not a body, but an act of a body.
Reply Obj. 1: As everything which is in motion must be moved by something else, a process which cannot be prolonged indefinitely, we must allow that not every mover is moved. For, since to be moved is to pass from potentiality to actuality, the mover gives what it has to the thing moved, inasmuch as it causes it to be in act. But, as is shown in _Phys._ viii, 6, there is a mover which is altogether immovable, and not moved either essentially, or accidentally; and such a mover can cause an invariable movement. There is, however, another kind of mover, which, though not moved essentially, is moved accidentally; and for this reason it does not cause an invariable movement; such a mover, is the soul. There is, again, another mover, which is moved essentially--namely, the body. And because the philosophers of old believed that nothing existed but bodies, they maintained that every mover is moved; and that the soul is moved directly, and is a body. Reply Obj. 2: The likeness of a thing known is not of necessity actually in the nature of the knower; but given a thing which knows potentially, and afterwards knows actually, the likeness of the thing known must be in the nature of the knower, not actually, but only potentially; thus color is not actually in the pupil of the eye, but only potentially. Hence it is necessary, not that the likeness of corporeal things should be actually in the nature of the soul, but that there be a potentiality in the soul for such a likeness. But the ancient philosophers omitted to distinguish between actuality and potentiality; and so they held that the soul must be a body in order to have knowledge of a body; and that it must be composed of the principles of which all bodies are formed in order to know all bodies.
Reply Obj. 3: There are two kinds of contact; of "quantity," and of "power." By the former a body can be touched only by a body; by the latter a body can be touched by an incorporeal thing, which moves that body. _______________________ SECOND ARTICLE [I, Q. 75, Art. 2] Whether the Human Soul Is Something Subsistent? Objection 1: It would seem that the human soul is not something subsistent. For that which subsists is said to be "this particular thing." Now "this particular thing" is said not of the soul, but of that which is composed of soul and body. Therefore the soul is not something subsistent. Obj. 2: Further, everything subsistent operates. But the soul does not operate; for, as the Philosopher says (De Anima i, 4), "to say that the soul feels or understands is like saying that the soul weaves or builds." Therefore the soul is not subsistent. Obj. 3: Further, if the soul were subsistent, it would have some operation apart from the body. But it has no operation apart from the body, not even that of understanding: for the act of understanding does not take place without a phantasm, which cannot exist apart from the body. Therefore the human soul is not something subsistent. _On the contrary,_ Augustine says (De Trin. x, 7): "Who understands that the nature of the soul is that of a substance and not that of a body, will see that those who maintain the corporeal nature of the soul, are led astray through associating with the soul those things without which they are unable to think of any nature--i.e. imaginary pictures of corporeal things." Therefore the nature of the human intellect is not only incorporeal, but it is also a substance, that is, something subsistent.
_I answer that,_ It must necessarily be allowed that the principle of intellectual operation which we call the soul, is a principle both incorporeal and subsistent. For it is clear that by means of the intellect man can have knowledge of all corporeal things. Now whatever knows certain things cannot have any of them in its own nature; because that which is in it naturally would impede the knowledge of anything else. Thus we observe that a sick man's tongue being vitiated by a feverish and bitter humor, is insensible to anything sweet, and everything seems bitter to it. Therefore, if the intellectual principle contained the nature of a body it would be unable to know all bodies. Now every body has its own determinate nature. Therefore it is impossible for the intellectual principle to be a body. It is likewise impossible for it to understand by means of a bodily organ; since the determinate nature of that organ would impede knowledge of all bodies; as when a certain determinate color is not only in the pupil of the eye, but also in a glass vase, the liquid in the vase seems to be of that same color. Therefore the intellectual principle which we call the mind or the intellect has an operation _per se_ apart from the body. Now only that which subsists can have an operation _per se._ For nothing can operate but what is actual: for which reason we do not say that heat imparts heat, but that what is hot gives heat. We must conclude, therefore, that the human soul, which is called the intellect or the mind, is something incorporeal and subsistent.
Reply Obj. 1: "This particular thing" can be taken in two senses. Firstly, for anything subsistent; secondly, for that which subsists, and is complete in a specific nature. The former sense excludes the inherence of an accident or of a material form; the latter excludes also the imperfection of the part, so that a hand can be called "this particular thing" in the first sense, but not in the second. Therefore, as the human soul is a part of human nature, it can indeed be called "this particular thing," in the first sense, as being something subsistent; but not in the second, for in this sense, what is composed of body and soul is said to be "this particular thing."
THIRD ARTICLE [I, Q. 75, Art. 3] Whether the Souls of Brute Animals Are Subsistent? Objection 1: It would seem that the souls of brute animals are subsistent. For man is of the same genus as other animals; and, as we have just shown (A. 2), the soul of man is subsistent. Therefore the souls of other animals are subsistent. Obj. 2: Further, the relation of the sensitive faculty to sensible objects is like the relation of the intellectual faculty to intelligible objects. But the intellect, apart from the body, apprehends intelligible objects. Therefore the sensitive faculty, apart from the body, perceives sensible objects. Therefore, since the souls of brute animals are sensitive, it follows that they are subsistent; just as the human intellectual soul is subsistent. Obj. 3: Further, the soul of brute animals moves the body. But the body is not a mover, but is moved. Therefore the soul of brute animals has an operation apart from the body. _On the contrary,_ Is what is written in the book De Eccl. Dogm. xvi, xvii: "Man alone we believe to have a subsistent soul: whereas the souls of animals are not subsistent."
_I answer that,_ The ancient philosophers made no distinction between sense and intellect, and referred both to a corporeal principle, as has been said (A. 1). Plato, however, drew a distinction between intellect and sense; yet he referred both to an incorporeal principle, maintaining that sensing, just as understanding, belongs to the soul as such. From this it follows that even the souls of brute animals are subsistent. But Aristotle held that of the operations of the soul, understanding alone is performed without a corporeal organ. On the other hand, sensation and the consequent operations of the sensitive soul are evidently accompanied with change in the body; thus in the act of vision, the pupil of the eye is affected by a reflection of color: and so with the other senses. Hence it is clear that the sensitive soul has no _per se_ operation of its own, and that every operation of the sensitive soul belongs to the composite. Wherefore we conclude that as the souls of brute animals have no _per se_ operations they are not subsistent. For the operation of anything follows the mode of its being. Reply Obj. 1: Although man is of the same genus as other animals, he is of a different species. Specific difference is derived from the difference of form; nor does every difference of form necessarily imply a diversity of genus.
FOURTH ARTICLE [I, Q. 75, Art. 4] Whether the Soul Is Man? Objection 1: It would seem that the soul is man. For it is written (2 Cor. 4:16): "Though our outward man is corrupted, yet the inward man is renewed day by day." But that which is within man is the soul. Therefore the soul is the inward man. Obj. 2: Further, the human soul is a substance. But it is not a universal substance. Therefore it is a particular substance. Therefore it is a "hypostasis" or a person; and it can only be a human person. Therefore the soul is man; for a human person is a man. _On the contrary,_ Augustine (De Civ. Dei xix, 3) commends Varro as holding "that man is not a mere soul, nor a mere body; but both soul and body."
_I answer that,_ The assertion "the soul is man," can be taken in two senses. First, that man is a soul; though this particular man, Socrates, for instance, is not a soul, but composed of soul and body. I say this, forasmuch as some held that the form alone belongs to the species; while matter is part of the individual, and not the species. This cannot be true; for to the nature of the species belongs what the definition signifies; and in natural things the definition does not signify the form only, but the form and the matter. Hence in natural things the matter is part of the species; not, indeed, signate matter, which is the principle of individuality; but the common matter. For as it belongs to the notion of this particular man to be composed of this soul, of this flesh, and of these bones; so it belongs to the notion of man to be composed of soul, flesh, and bones; for whatever belongs in common to the substance of all the individuals contained under a given species, must belong to the substance of the species.
It may also be understood in this sense, that this soul is this man; and this could be held if it were supposed that the operation of the sensitive soul were proper to it, apart from the body; because in that case all the operations which are attributed to man would belong to the soul only; and whatever performs the operations proper to a thing, is that thing; wherefore that which performs the operations of a man is man. But it has been shown above (A. 3) that sensation is not the operation of the soul only. Since, then, sensation is an operation of man, but not proper to him, it is clear that man is not a soul only, but something composed of soul and body. Plato, through supposing that sensation was proper to the soul, could maintain man to be a soul making use of the body. Reply Obj. 1: According to the Philosopher (Ethic. ix, 8), a thing seems to be chiefly what is princip[al] in it; thus what the governor of a state does, the state is said to do. In this way sometimes what is princip[al] in man is said to be man; sometimes, indeed, the intellectual part which, in accordance with truth, is called the "inward" man; and sometimes the sensitive part with the body is called man in the opinion of those whose observation does not go beyond the senses. And this is called the "outward" man.
Reply Obj. 2: Not every particular substance is a hypostasis or a person, but that which has the complete nature of its species. Hence a hand, or a foot, is not called a hypostasis, or a person; nor, likewise, is the soul alone so called, since it is a part of the human species. _______________________ FIFTH ARTICLE [I, Q. 75, Art. 5] Whether the Soul Is Composed of Matter and Form? Objection 1: It would seem that the soul is composed of matter and form. For potentiality is opposed to actuality. Now, whatsoever things are in actuality participate of the First Act, which is God; by participation of Whom, all things are good, are beings, and are living things, as is clear from the teaching of Dionysius (Div. Nom. v). Therefore whatsoever things are in potentiality participate of the first potentiality. But the first potentiality is primary matter. Therefore, since the human soul is, after a manner, in potentiality; which appears from the fact that sometimes a man is potentially understanding; it seems that the human soul must participate of primary matter, as part of itself. Obj. 2: Further, wherever the properties of matter are found, there matter is. But the properties of matter are found in the soul--namely, to be a subject, and to be changed, for it is a subject to science, and virtue; and it changes from ignorance to knowledge and from vice to virtue. Therefore matter is in the soul.
Obj. 3: Further, things which have no matter, have no cause of their existence, as the Philosopher says _Metaph._ viii (Did. vii, 6). But the soul has a cause of its existence, since it is created by God. Therefore the soul has matter. Obj. 4: Further, what has no matter, and is a form only, is a pure act, and is infinite. But this belongs to God alone. Therefore the soul has matter. _On the contrary,_ Augustine (Gen. ad lit. vii, 7,8,9) proves that the soul was made neither of corporeal matter, nor of spiritual matter. _I answer that,_ The soul has no matter. We may consider this question in two ways. First, from the notion of a soul in general; for it belongs to the notion of a soul to be the form of a body. Now, either it is a form by virtue of itself, in its entirety, or by virtue of some part of itself. If by virtue of itself in its entirety, then it is impossible that any part of it should be matter, if by matter we understand something purely potential: for a form, as such, is an act; and that which is purely potentiality cannot be part of an act, since potentiality is repugnant to actuality as being opposite thereto. If, however, it be a form by virtue of a part of itself, then we call that part the soul: and that matter, which it actualizes first, we call the "primary animate."
Secondly, we may proceed from the specific notion of the human soul inasmuch as it is intellectual. For it is clear that whatever is received into something is received according to the condition of the recipient. Now a thing is known in as far as its form is in the knower. But the intellectual soul knows a thing in its nature absolutely: for instance, it knows a stone absolutely as a stone; and therefore the form of a stone absolutely, as to its proper formal idea, is in the intellectual soul. Therefore the intellectual soul itself is an absolute form, and not something composed of matter and form. For if the intellectual soul were composed of matter and form, the forms of things would be received into it as individuals, and so it would only know the individual: just as it happens with the sensitive powers which receive forms in a corporeal organ; since matter is the principle by which forms are individualized. It follows, therefore, that the intellectual soul, and every intellectual substance which has knowledge of forms absolutely, is exempt from composition of matter and form.
Reply Obj. 1: The First Act is the universal principle of all acts; because It is infinite, virtually "precontaining all things," as Dionysius says (Div. Nom. v). Wherefore things participate of It not as a part of themselves, but by diffusion of Its processions. Now as potentiality is receptive of act, it must be proportionate to act. But the acts received which proceed from the First Infinite Act, and are participations thereof, are diverse, so that there cannot be one potentiality which receives all acts, as there is one act, from which all participated acts are derived; for then the receptive potentiality would equal the active potentiality of the First Act. Now the receptive potentiality in the intellectual soul is other than the receptive potentiality of first matter, as appears from the diversity of the things received by each. For primary matter receives individual forms; whereas the intelligence receives absolute forms. Hence the existence of such a potentiality in the intellectual soul does not prove that the soul is composed of matter and form. Reply Obj. 2: To be a subject and to be changed belong to matter by reason of its being in potentiality. As, therefore, the potentiality of the intelligence is one thing and the potentiality of primary matter another, so in each is there a different reason of subjection and change. For the intelligence is subject to knowledge, and is changed from ignorance to knowledge, by reason of its being in potentiality with regard to the intelligible species.
SIXTH ARTICLE [I, Q. 75, Art. 6] Whether the Human Soul Is Incorruptible? Objection 1: It would seem that the human soul is corruptible. For those things that have a like beginning and process seemingly have a like end. But the beginning, by generation, of men is like that of animals, for they are made from the earth. And the process of life is alike in both; because "all things breathe alike, and man hath nothing more than the beast," as it is written (Eccles. 3:19). Therefore, as the same text concludes, "the death of man and beast is one, and the condition of both is equal." But the souls of brute animals are corruptible. Therefore, also, the human soul is corruptible. Obj. 2: Further, whatever is out of nothing can return to nothingness; because the end should correspond to the beginning. But as it is written (Wis. 2:2), "We are born of nothing"; which is true, not only of the body, but also of the soul. Therefore, as is concluded in the same passage, "After this we shall be as if we had not been," even as to our soul. Obj. 3: Further, nothing is without its own proper operation. But the operation proper to the soul, which is to understand through a phantasm, cannot be without the body. For the soul understands nothing without a phantasm; and there is no phantasm without the body as the Philosopher says (De Anima i, 1). Therefore the soul cannot survive the dissolution of the body.
Ideas discussed in this chapter
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