Summa Th. I EN Qu.76 a.8
Objection: 1. It would seem that the whole soul is not in each part of the body; for the Philosopher says in De causa motus animalium (De mot. animal. x): "It is not necessary for the soul to be in each part of the body; it suffices that it be in some principle of the body causing the other parts to live, for each part has a natural movement of its own."
2. Further, the soul is in the body of which it is the act. But it is the act of an organic body. Therefore it exists only in an organic body. But each part of the human body is not an organic body. Therefore the whole soul is not in each part.
3. Further, the Philosopher says (De Anima. ii, 1) that the relation of a part of the soul to a part of the body, such as the sight to the pupil of the eye, is the same as the relation of the soul to the whole body of an animal. If, therefore, the whole soul is in each part of the body, it follows that each part of the body is an animal.
4. Further, all the powers of the soul are rooted in the essence of the soul. If, therefore, the whole soul be in each part of the body, it follows that all the powers of the soul are in each part of the body; thus the sight will be in the ear, and hearing in the eye, and this is absurd.
5. Further, if the whole soul is in each part of the body, each part of the body is immediately dependent on the soul. Thus one part would not depend on another; nor would one part be nobler than another; which is clearly untrue. Therefore the soul is not in each part of the body.
On the contrary Augustine says (De Trin. vi, 6), that "in each body the whole soul is in the whole body, and in each part is entire."
I answer that As we have said, if the soul were united to the body merely as its motor, we might say that it is not in each part of the body, but only in one part through which it would move the others. But since the soul is united to the body as its form, it must necessarily be in the whole body, and in each part thereof. For it is not an accidental form, but the substantial form of the body. Now the substantial form perfects not only the whole, but each part of the whole. For since a whole consists of parts, a form of the whole which does not give existence to each of the parts of the body, is a form consisting in composition and order, such as the form of a house; and such a form is accidental. But the soul is a substantial form; and therefore it must be the form and the act, not only of the whole, but also of each part. Therefore, on the withdrawal of the soul, as we do not speak of an animal or a man unless equivocally, as we speak of a painted animal or a stone animal; so is it with the hand, the eye, the flesh and bones, as the Philosopher says (De Anima ii, 1). A proof of which is, that on the withdrawal of the soul, no part of the body retains its proper action; although that which retains its species, retains the action of the species. But act is in that which it actuates: wherefore the soul must be in the whole body, and in each part thereof.
That it is entire in each part thereof, may be concluded from this, that since a whole is that which is divided into parts, there are three kinds of totality, corresponding to three kinds of division. There is a whole which is divided into parts of quantity, as a whole line, or a whole body. There is also a whole which is divided into logical and essential parts: as a thing defined is divided into the parts of a definition, and a composite into matter and form. There is, further, a third kind of whole which is potential, divided into virtual parts. The first kind of totality does not apply to forms, except perhaps accidentally; and then only to those forms, which have an indifferent relationship to a quantitative whole and its parts; as whiteness, as far as its essence is concerned, is equally disposed to be in the whole surface and in each part of the surface; and, therefore, the surface being divided, the whiteness is accidentally divided. But a form which requires variety in the parts, such as a soul, and specially the soul of perfect animals, is not equally related to the whole and the parts: hence it is not divided accidentally when the whole is divided. So therefore quantitative totality cannot be attributed to the soul, either essentially or accidentally. But the second kind of totality, which depends on logical and essential perfection, properly and essentially belongs to forms: and likewise the virtual totality, because a form is the principle of operation.
Therefore if it be asked whether the whole whiteness is in the whole surface and in each part thereof, it is necessary to distinguish. If we mean quantitative totality which whiteness has accidentally, then the whole whiteness is not in each part of the surface. The same is to be said of totality of power: since the whiteness which is in the whole surface moves the sight more than the whiteness which is in a small part thereof. But if we mean totality of species and essence, then the whole whiteness is in each part of a surface.
Since, however, the soul has not quantitative totality, neither essentially, nor accidentally, as we have seen; it is enough to say that the whole soul is in each part of the body, by totality of perfection and of essence, but not by totality of power. For it is not in each part of the body, with regard to each of its powers; but with regard to sight, it is in the eye; and with regard to hearing, it is in the ear; and so forth. We must observe, however, that since the soul requires variety of parts, its relation to the whole is not the same as its relation to the parts; for to the whole it is compared primarily and essentially, as to its proper and proportionate perfectible; but to the parts, secondarily, inasmuch as they are ordained to the whole.
Reply to Objection: 1. The Philosopher is speaking there of the motive power of the soul.
2. The soul is the act of an organic body, as of its primary and proportionate perfectible.
3. An animal is that which is composed of a soul and a whole body, which is the soul's primary and proportionate perfectible. Thus the soul is not in a part. Whence it does not follow that a part of an animal is an animal.
4. Some of the powers of the soul are in it according as it exceeds the entire capacity of the body, namely the intellect and the will; whence these powers are not said to be in any part of the body. Other powers are common to the soul and body; wherefore each of these powers need not be wherever the soul is, but only in that part of the body, which is adapted to the operation of such a power.
5. One part of the body is said to be nobler than another, on account of the various powers, of which the parts of the body are the organs. For that part which is the organ of a nobler power, is a nobler part of the body: as also is that part which serves the same power in a nobler manner.
We proceed to consider those things which belong to the powers of the soul; first, in general, secondly, in particular. Under the first head there are eight points of inquiry:
(1) Whether the essence of the soul is its power?
(2) Whether there is one power of the soul, or several?
(3) How the powers of the soul are distinguished from one another?
(4) Of the orders of the powers, one to another;
(5) Whether the powers of the soul are in it as in their subject?
(6) Whether the powers flow from the essence of the soul?
(7) Whether one power rises from another?
(8) Whether all the powers of the soul remain in the soul after death?
Objection: 1. It would seem that the essence of the soul is its power. For Augustine says (De Trin. ix, 4), that "mind, knowledge, and love are in the soul substantially, or, which is the same thing, essentially": and (De Trin. x, 11), that "memory, understanding, and will are one life, one mind, one essence."
2. Further, the soul is nobler than primary matter. But primary matter is its own potentiality. Much more therefore is the soul its own power.
3. Further, the substantial form is simpler than the accidental form; a sign of which is that the substantial form is not intensified or relaxed, but is indivisible. But the accidental form is its own power. Much more therefore is that substantial form which is the soul.
4. Further, we sense by the sensitive power and we understand by the intellectual power. But "that by which we first sense and understand" is the soul, according to the Philosopher (De Anima ii, 2). Therefore the soul is its own power.
5. Further, whatever does not belong to the essence is an accident. Therefore if the power of the soul is something else besides the essence thereof, it is an accident, which is contrary to Augustine, who says that the foregoing (see OBJ 1) "are not in the soul as in a subject as color or shape, or any other quality, or quantity, are in a body; for whatever is so, does not exceed the subject in which it is: Whereas the mind can love and know other things" (De Trin. ix, 4).
6. Further, " a simple form cannot be a subject." But the soul is a simple form; since it is not composed of matter and form, as we have said above (Question , Article ). Therefore the power of the soul cannot be in it as in a subject.
7. Further, an accident is not the principle of a substantial difference. But sensitive and rational are substantial differences; and they are taken from sense and reason, which are powers of the soul. Therefore the powers of the soul are not accidents; and so it would seem that the power of the soul is its own essence.
On the contrary Dionysius (Coel. Hier. xi) says that "heavenly spirits are divided into essence, power, and operation." Much more, then, in the soul is the essence distinct from the virtue or power.
I answer that It is impossible to admit that the power of the soul is its essence, although some have maintained it. For the present purpose this may be proved in two ways. First, because, since power and act divide being and every kind of being, we must refer a power and its act to the same genus. Therefore, if the act be not in the genus of substance, the power directed to that act cannot be in the genus of substance. Now the operation of the soul is not in the genus of substance; for this belongs to God alone, whose operation is His own substance. Wherefore the Divine power which is the principle of His operation is the Divine Essence itself. This cannot be true either of the soul, or of any creature; as we have said above when speaking of the angels (Question , Article ). Secondly, this may be also shown to be impossible in the soul. For the soul by its very essence is an act. Therefore if the very essence of the soul were the immediate principle of operation, whatever has a soul would always have actual vital actions, as that which has a soul is always an actually living thing. For as a form the soul is not an act ordained to a further act, but the ultimate term of generation. Wherefore, for it to be in potentiality to another act, does not belong to it according to its essence, as a form, but according to its power. So the soul itself, as the subject of its power, is called the first act, with a further relation to the second act. Now we observe that what has a soul is not always actual with respect to its vital operations; whence also it is said in the definition of the soul, that it is "the act of a body having life potentially"; which potentiality, however, "does not exclude the soul." Therefore it follows that the essence of the soul is not its power. For nothing is in potentiality by reason of an act, as act.
Reply to Objection: 1. Augustine is speaking of the mind as it knows and loves itself. Thus knowledge and love as referred to the soul as known and loved, are substantially or essentially in the soul, for the very substance or essence of the soul is known and loved. In the same way are we to understand what he says in the other passage, that those things are "one life, one mind, one essence." Or, as some say, this passage is true in the sense in which the potential whole is predicated of its parts, being midway between the universal whole, and the integral whole. For the universal whole is in each part according to its entire essence and power; as animal in a man and in a horse; and therefore it is properly predicated of each part. But the integral whole is not in each part, neither according to its whole essence, nor according to its whole power. Therefore in no way can it be predicated of each part; yet in a way it is predicated, though improperly, of all the parts together; as if we were to say that the wall, roof, and foundations are a house. But the potential whole is in each part according to its whole essence, not, however, according to its whole power. Therefore in a way it can be predicated of each part, but not so properly as the universal whole. In this sense, Augustine says that the memory, understanding, and the will are the one essence of the soul.
2. The act to which primary matter is in potentiality is the substantial form. Therefore the potentiality of matter is nothing else but its essence.
3. Action belongs to the composite, as does existence; for to act belongs to what exists. Now the composite has substantial existence through the substantial form; and it operates by the power which results from the substantial form. Hence an active accidental form is to the substantial form of the agent (for instance, heat compared to the form of fire) as the power of the soul is to the soul.
4. That the accidental form is a principle of action is due to the substantial form. Therefore the substantial form is the first principle of action; but not the proximate principle. In this sense the Philosopher says that "the soul is that whereby we understand and sense."
5. If we take accident as meaning what is divided against substance, then there can be no medium between substance and accident; because they are divided by affirmation and negation, that is, according to existence in a subject, and non-existence in a subject. In this sense, as the power of the soul is not its essence, it must be an accident; and it belongs to the second species of accident, that of quality. But if we take accident as one of the five universals, in this sense there is a medium between substance and accident. For the substance is all that belongs to the essence of a thing; whereas whatever is beyond the essence of a thing cannot be called accident in this sense; but only what is not caused by the essential principle of the species. For the 'proper' does not belong to the essence of a thing, but is caused by the essential principles of the species; wherefore it is a medium between the essence and accident thus understood. In this sense the powers of the soul may be said to be a medium between substance and accident, as being natural properties of the soul. When Augustine says that knowledge and love are not in the soul as accidents in a subject, this must be understood in the sense given above, inasmuch as they are compared to the soul, not as loving and knowing, but as loved and known. His argument proceeds in this sense; for if love were in the soul loved as in a subject, it would follow that an accident transcends its subject, since even other things are loved through the soul.
6. Although the soul is not composed of matter and form, yet it has an admixture of potentiality, as we have said above (Question , Article , ad 4); and for this reason it can be the subject of an accident. The statement quoted is verified in God, Who is the Pure Act; in treating of which subject Boethius employs that phrase (De Trin. i).
7. Rational and sensitive, as differences, are not taken from the powers of sense and reason, but from the sensitive and rational soul itself. But because substantial forms, which in themselves are unknown to us, are known by their accidents; nothing prevents us from sometimes substituting accidents for substantial differences.
Objection: 1. It would seem that there are not several powers of the soul. For the intellectual soul approaches nearest to the likeness of God. But in God there is one simple power: and therefore also in the intellectual soul.
2. Further, the higher a power is, the more unified it is. But the intellectual soul excels all other forms in power. Therefore above all others it has one virtue or power.
3. Further, to operate belongs to what is in act. But by the one essence of the soul, man has actual existence in the different degrees of perfection, as we have seen above (Question , Articles ,4). Therefore by the one power of the soul he performs operations of various degrees.
On the contrary The Philosopher places several powers in the soul (De Anima ii, 2,3).
I answer that Of necessity we must place several powers in the soul. To make this evident, we observe that, as the Philosopher says (De Coelo ii, 12), the lowest order of things cannot acquire perfect goodness, but they acquire a certain imperfect goodness, by few movements; and those which belong to a higher order acquire perfect goodness by many movements; and those yet higher acquire perfect goodness by few movements; and the highest perfection is found in those things which acquire perfect goodness without any movement whatever. Thus he is least of all disposed of health, who can only acquire imperfect health by means of a few remedies; better disposed is he who can acquire perfect health by means of many remedies; and better still, he who can by few remedies; best of all is he who has perfect health without any remedies. We conclude, therefore, that things which are below man acquire a certain limited goodness; and so they have a few determinate operations and powers. But man can acquire universal and perfect goodness, because he can acquire beatitude. Yet he is in the last degree, according to his nature, of those to whom beatitude is possible; therefore the human soul requires many and various operations and powers. But to angels a smaller variety of powers is sufficient. In God there is no power or action beyond His own Essence.
There is yet another reason why the human soul abounds in a variety of powers---because it is on the confines of spiritual and corporeal creatures; and therefore the powers of both meet together in the soul.
Reply to Objection: 1. The intellectual soul approaches to the Divine likeness, more than inferior creatures, in being able to acquire perfect goodness; although by many and various means; and in this it falls short of more perfect creatures.
2. A unified power is superior if it extends to equal things: but a multiform power is superior to it, if it is over many things.
3. One thing has one substantial existence, but may have several operations. So there is one essence of the soul, with several powers.
Objection: 1. It would seem that the powers of the soul are not distinguished by acts and objects. For nothing is determined to its species by what is subsequent and extrinsic to it. But the act is subsequent to the power; and the object is extrinsic to it. Therefore the soul's powers are not specifically distinct by acts and objects.
2. Further, contraries are what differ most from each other. Therefore if the powers are distinguished by their objects, it follows that the same power could not have contrary objects. This is clearly false in almost all the powers; for the power of vision extends to white and black, and the power to taste to sweet and bitter.
3. Further, if the cause be removed, the effect is removed. Hence if the difference of powers came from the difference of objects, the same object would not come under different powers. This is clearly false; for the same thing is known by the cognitive power, and desired by the appetitive.
4. Further, that which of itself is the cause of anything, is the cause thereof, wherever it is. But various objects which belong to various powers, belong also to some one power; as sound and color belong to sight and hearing, which are different powers, yet they come under the one power of common sense. Therefore the powers are not distinguished according to the difference of their objects.
On the contrary Things that are subsequent are distinguished by what precedes. But the Philosopher says (De Anima ii, 4) that "acts and operations precede the powers according to reason; and these again are preceded by their opposites," that is their objects. Therefore the powers are distinguished according to their acts and objects.
I answer that A power as such is directed to an act. Wherefore we seek to know the nature of a power from the act to which it is directed, and consequently the nature of a power is diversified, as the nature of the act is diversified. Now the nature of an act is diversified according to the various natures of the objects. For every act is either of an active power or of a passive power. Now, the object is to the act of a passive power, as the principle and moving cause: for color is the principle of vision, inasmuch as it moves the sight. On the other hand, to the act of an active power the object is a term and end; as the object of the power of growth is perfect quantity, which is the end of growth. Now, from these two things an act receives its species, namely, from its principle, or from its end or term; for the act of heating differs from the act of cooling, in this, that the former proceeds from something hot, which is the active principle, to heat; the latter from something cold, which is the active principle, to cold. Therefore the powers are of necessity distinguished by their acts and objects.
Nevertheless, we must observe that things which are accidental do not change the species. For since to be colored is accidental to an animal, its species is not changed by a difference of color, but by a difference in that which belongs to the nature of an animal, that is to say, by a difference in the sensitive soul, which is sometimes rational, and sometimes otherwise. Hence "rational" and "irrational" are differences dividing animal, constituting its various species. In like manner therefore, not any variety of objects diversifies the powers of the soul, but a difference in that to which the power of its very nature is directed. Thus the senses of their very nature are directed to the passive quality which of itself is divided into color, sound, and the like, and therefore there is one sensitive power with regard to color, namely, the sight, and another with regard to sound, namely, hearing. But it is accidental to a passive quality, for instance, to something colored, to be a musician or a grammarian, great or small, a man or a stone. Therefore by reason of such differences the powers of the soul are not distinct.
Reply to Objection: 1. Act, though subsequent in existence to power, is, nevertheless, prior to it in intention and logically; as the end is with regard to the agent. And the object, although extrinsic, is, nevertheless, the principle or end of the action; and those conditions which are intrinsic to a thing, are proportionate to its principle and end.
2. If any power were to have one of two contraries as such for its object, the other contrary would belong to another power. But the power of the soul does not regard the nature of the contrary as such, but rather the common aspect of both contraries; as sight does not regard white as such, but as color. This is because of two contraries one, in a manner, includes the idea of the other, since they are to one another as perfect and imperfect.
3. Nothing prevents things which coincide in subject, from being considered under different aspects; therefore they can belong to various powers of the soul.
4. The higher power of itself regards a more universal formality of the object than the lower power; because the higher a power is, to a greater number of things does it extend. Therefore many things are combined in the one formality of the object, which the higher power considers of itself; while they differ in the formalities regarded by the lower powers of themselves. Thus it is that various objects belong to various lower powers; which objects, however, are subject to one higher power.
Objection: 1. It would seem that there is no order among the powers of the soul. For in those things which come under one division, there is no before and after, but all are naturally simultaneous. But the powers of the soul are contradistinguished from one another. Therefore there is no order among them.
2. Further, the powers of the soul are referred to their objects and to the soul itself. On the part of the soul, there is not order among them, because the soul is one. In like manner the objects are various and dissimilar, as color and sound. Therefore there is no order among the powers of the soul.
3. Further, where there is order among powers, we find that the operation of one depends on the operation of another. But the action of one power of the soul does not depend on that of another; for sight can act independently of hearing, and conversely. Therefore there is no order among the powers of the soul.
On the contrary The Philosopher (De Anima ii, 3) compares the parts or powers of the soul to figures. But figures have an order among themselves. Therefore the powers of the soul have order.
I answer that, Since the soul is one, and the powers are many; and since a number of things that proceed from one must proceed in a certain order; there must be some order among the powers of the soul. Accordingly we may observe a triple order among them, two of which correspond to the dependence of one power on another; while the third is taken from the order of the objects. Now the dependence of one power on another can be taken in two ways; according to the order of nature, forasmuch as perfect things are by their nature prior to imperfect things; and according to the order of generation and time; forasmuch as from being imperfect, a thing comes to be perfect. Thus, according to the first kind of order among the powers, the intellectual powers are prior to the sensitive powers; wherefore they direct them and command them. Likewise the sensitive powers are prior in this order to the powers of the nutritive soul.
In the second kind of order, it is the other way about. For the powers of the nutritive soul are prior by way of generation to the powers of the sensitive soul; for which, therefore, they prepare the body. The same is to be said of the sensitive powers with regard to the intellectual. But in the third kind of order, certain sensitive powers are ordered among themselves, namely, sight, hearing, and smelling. For the visible naturally comes first; since it is common to higher and lower bodies. But sound is audible in the air, which is naturally prior to the mingling of elements, of which smell is the result.
Reply to Objection: 1. The species of a given genus are to one another as before and after, like numbers and figures, if considered in their nature; although they may be said to be simultaneous, according as they receive the predication of the common genus.
2. This order among the powers of the soul is both on the part of the soul (which, though it be one according to its essence, has a certain aptitude to various acts in a certain order) and on the part of the objects, and furthermore on the part of the acts, as we have said above.
3. This argument is verified as regards those powers among which order of the third kind exists. Those powers among which the two other kinds of order exist are such that the action of one depends on another.
Objection: 1. It would seem that all the powers of the soul are in the soul as their subject. For as the powers of the body are to the body; so are the powers of the soul to the soul. But the body is the subject of the corporeal powers. Therefore the soul is the subject of the powers of the soul.
2. Further, the operations of the powers of the soul are attributed to the body by reason of the soul; because, as the Philosopher says (De Anima ii, 2), "The soul is that by which we sense and understand primarily." But the natural principles of the operations of the soul are the powers. Therefore the powers are primarily in the soul.
3. Further, Augustine says (Gn ad lit. xii, 7,24) that the soul senses certain things, not through the body, in fact, without the body, as fear and such like; and some things through the body. But if the sensitive powers were not in the soul alone as their subject, the soul could not sense anything without the body. Therefore the soul is the subject of the sensitive powers; and for a similar reason, of all the other powers.
On the contrary The Philosopher says (De Somno et Vigilia i) that "sensation belongs neither to the soul, nor to the body, but to the composite." Therefore the sensitive power is in "the composite" as its subject. Therefore the soul alone is not the subject of all the powers.
I answer that The subject of operative power is that which is able to operate, for every accident denominates its proper subject. Now the same is that which is able to operate, and that which does operate. Wherefore the "subject of power" is of necessity "the subject of operation," as again the Philosopher says in the beginning of De Somno et Vigilia. Now, it is clear from what we have said above (Question , Articles ,3; Question , Article , ad 1), that some operations of the soul are performed without a corporeal organ, as understanding and will. Hence the powers of these operations are in the soul as their subject. But some operations of the soul are performed by means of corporeal organs; as sight by the eye, and hearing by the ear. And so it is with all the other operations of the nutritive and sensitive parts. Therefore the powers which are the principles of these operations have their subject in the composite, and not in the soul alone.
Reply to Objection: 1. All the powers are said to belong to the soul, not as their subject, but as their principle; because it is by the soul that the composite has the power to perform such operations.
2. All such powers are primarily in the soul, as compared to the composite; not as in their subject, but as in their principle.
3. Plato's opinion was that sensation is an operation proper to the soul, just as understanding is. Now in many things relating to Philosophy Augustine makes use of the opinions of Plato, not asserting them as true, but relating them. However, as far as the present question is concerned, when it is said that the soul senses some things with the body, and some without the body, this can be taken in two ways. Firstly, the words "with the body or without the body" may determine the act of sense in its mode of proceeding from the sentient. Thus the soul senses nothing without the body, because the action of sensation cannot proceed from the soul except by a corporeal organ. Secondly, they may be understood as determining the act of sense on the part of the object sensed. Thus the soul senses some things with the body, that is, things existing in the body, as when it feels a wound or something of that sort; while it senses some things without the body, that is, which do not exist in the body, but only in the apprehension of the soul, as when it feels sad or joyful on hearing something.
Summa Th. I EN Qu.76 a.8