How the Soul While United to the Body Understands Corporeal Things Beneath It

How the Soul While United to the Body Understands Corporeal Things Beneath It — St. Thomas Aquinas asks: Whether the soul knows bodies through the intellect?; Whether the soul understands corporeal things through its essence?; Whether the soul understands all things through innate species?; Whether the intelligible species are derived by the soul from certain separate forms?; Whether the intellectual soul knows material things in the eternal types?; Whether intellectual knowledge is derived from sensible things?; Whether the intellect can actually understand through the intelligible species of which it is possessed, without turning to the phantasms?; Whether the judgment of the intellect is hindered through suspension of the sensitive powers?.

We now have to consider the acts of the soul in regard to the intellectual and the appetitive powers: for the other powers of the soul do not come directly under the consideration of the theologian. Furthermore, the acts of the appetitive part of the soul come under the consideration of the science of morals; wherefore we shall treat of them in the second part of this work, to which the consideration of moral matters belongs. But of the acts of the intellectual part we shall treat now.

In treating of these acts we shall proceed in the following order: First, we shall inquire how the soul understands when united to the body; secondly, how it understands when separated therefrom.

The former of these inquiries will be threefold: (1) How the soul understands bodies which are beneath it; (2) How it understands itself and things contained in itself; (3) How it understands immaterial substances, which are above it.

In treating of the knowledge of corporeal things there are three points to be considered: (1) Through what does the soul know them? (2) How and in what order does it know them? (3) What does it know in them?

Under the first head there are eight points of inquiry:

Article 1: Whether the soul knows bodies through the intellect?

Science is in the intellect. If, therefore, the intellect does not know bodies, it follows that there is no science of bodies; and thus perishes natural science, which treats of mobile bodies.

It should be said in order to elucidate this question, that the early philosophers, who inquired into the natures of things, thought there was nothing in the world save bodies. And because they observed that all bodies are mobile, and considered them to be ever in a state of flux, they were of opinion that we can have no certain knowledge of the true nature of things. For what is in a continual state of flux, cannot be grasped with any degree of certitude, for it passes away ere the mind can form a judgment thereon: according to the saying of Heraclitus, that "it is not possible twice to touch a drop of water in a passing torrent," as the Philosopher relates (Metaph. iv, Did. iii, 5).

After these came Plato, who, wishing to save the certitude of our knowledge of truth through the intellect, maintained that, besides these things corporeal, there is another genus of beings, separate from matter and movement, which beings he called "species" or "ideas," by participation of which each one of these singular and sensible things is said to be either a man, or a horse, or the like. Wherefore he said that sciences and definitions, and whatever appertains to the act of the intellect, are not referred to these sensible bodies, but to those beings immaterial and separate: so that according to this the soul does not understand these corporeal things, but the separate species thereof.

Now this may be shown to be false for two reasons. First, because, since those species are immaterial and immovable, knowledge of movement and matter would be excluded from science (which knowledge is proper to natural science), and likewise all demonstration through moving and material causes. Secondly, because it seems ridiculous, when we seek for knowledge of things which are to us manifest, to introduce other beings, which cannot be the substance of those others, since they differ from them essentially: so that granted that we have a knowledge of those separate substances, we cannot for that reason claim to form a judgment concerning these sensible things.

Now it seems that Plato strayed from the truth because, having observed that all knowledge takes place through some kind of similitude, he thought that the form of the thing known must of necessity be in the knower in the same manner as in the thing known. Then he observed that the form of the thing understood is in the intellect under conditions of universality, immateriality, and immobility: which is apparent from the very operation of the intellect, whose act of understanding has a universal extension, and is subject to a certain amount of necessity: for the mode of action corresponds to the mode of the agent's form. Wherefore he concluded that the things which we understand must have in themselves an existence under the same conditions of immateriality and immobility.

But there is no necessity for this. For even in sensible things it is to be observed that the form is otherwise in one sensible than in another: for instance, whiteness may be of great intensity in one, and of a less intensity in another: in one we find whiteness with sweetness, in another without sweetness. In the same way the sensible form is conditioned differently in the thing which is external to the soul, and in the senses which receive the forms of sensible things without receiving matter, such as the color of gold without receiving gold. So also the intellect, according to its own mode, receives under conditions of immateriality and immobility, the species of material and mobile bodies: for the received is in the receiver according to the mode of the receiver. We must conclude, therefore, that through the intellect the soul knows bodies by a knowledge which is immaterial, universal, and necessary.

Article 2: Whether the soul understands corporeal things through its essence?

Augustine says (De Trin. ix, 3) that "the mind gathers knowledge of corporeal things through the bodily senses." But the soul itself cannot be known through the bodily senses. Therefore it does not know corporeal things through itself.

The ancient philosophers held that the soul knows bodies through its essence. For it was universally admitted that "like is known by like." But they thought that the form of the thing known is in the knower in the same mode as in the thing known. The Platonists however were of a contrary opinion. For Plato, having observed that the intellectual soul has an immaterial nature, and an immaterial mode of knowledge, held that the forms of things known subsist immaterially. While the earlier natural philosophers, observing that things known are corporeal and material, held that things known must exist materially even in the soul that knows them. And therefore, in order to ascribe to the soul a knowledge of all things, they held that it has the same nature in common with all. And because the nature of a result is determined by its principles, they ascribed to the soul the nature of a principle; so that those who thought fire to be the principle of all, held that the soul had the nature of fire; and in like manner as to air and water. Lastly, Empedocles, who held the existence of our four material elements and two principles of movement, said that the soul was composed of these. Consequently, since they held that things exist in the soul materially, they maintained that all the soul's knowledge is material, thus failing to discern intellect from sense.

But this opinion will not hold. First, because in the material principle of which they spoke, the various results do not exist save in potentiality. But a thing is not known according as it is in potentiality, but only according as it is in act, as is shown Metaph. ix (Did. viii, 9): wherefore neither is a power known except through its act. It is therefore insufficient to ascribe to the soul the nature of the principles in order to explain the fact that it knows all, unless we further admit in the soul natures and forms of each individual result, for instance, of bone, flesh, and the like; thus does Aristotle argue against Empedocles (De Anima i, 5). Secondly, because if it were necessary for the thing known to exist materially in the knower, there would be no reason why things which have a material existence outside the soul should be devoid of knowledge; why, for instance, if by fire the soul knows fire, that fire also which is outside the soul should not have knowledge of fire.

We must conclude, therefore, that material things known must needs exist in the knower, not materially, but immaterially. The reason of this is, because the act of knowledge extends to things outside the knower: for we know things even that are external to us. Now by matter the form of a thing is determined to some one thing. Wherefore it is clear that knowledge is in inverse ratio of materiality. And consequently things that are not receptive of forms save materially, have no power of knowledge whatever---such as plants, as the Philosopher says (De Anima ii, 12). But the more immaterially a thing receives the form of the thing known, the more perfect is its knowledge. Therefore the intellect which abstracts the species not only from matter, but also from the individuating conditions of matter, has more perfect knowledge than the senses, which receive the form of the thing known, without matter indeed, but subject to material conditions. Moreover, among the senses, sight has the most perfect knowledge, because it is the least material, as we have remarked above (): while among intellects the more perfect is the more immaterial.

It is therefore clear from the foregoing, that if there be an intellect which knows all things by its essence, then its essence must needs have all things in itself immaterially; thus the early philosophers held that the essence of the soul, that it may know all things, must be actually composed of the principles of all material things. Now this is proper to God, that His Essence comprise all things immaterially as effects pre-exist virtually in their cause. God alone, therefore, understands all things through His Essence: but neither the human soul nor the angels can do so.

Article 3: Whether the soul understands all things through innate species?

The Philosopher, speaking of the intellect, says (De Anima iii, 4) that it is like "a tablet on which nothing is written."

Since form is the principle of action, a thing must be related to the form which is the principle of an action, as it is to that action: for instance, if upward motion is from lightness, then that which only potentially moves upwards must needs be only potentially light, but that which actually moves upwards must needs be actually light. Now we observe that man sometimes is only a potential knower, both as to sense and as to intellect. And he is reduced from such potentiality to act---through the action of sensible objects on his senses, to the act of sensation---by instruction or discovery, to the act of understanding. Wherefore we must say that the cognitive soul is in potentiality both to the images which are the principles of sensing, and to those which are the principles of understanding. For this reason Aristotle (De Anima iii, 4) held that the intellect by which the soul understands has no innate species, but is at first in potentiality to all such species.

But since that which has a form actually, is sometimes unable to act according to that form on account of some hindrance, as a light thing may be hindered from moving upwards; for this reason did Plato hold that naturally man's intellect is filled with all intelligible species, but that, by being united to the body, it is hindered from the realization of its act. But this seems to be unreasonable. First, because, if the soul has a natural knowledge of all things, it seems impossible for the soul so far to forget the existence of such knowledge as not to know itself to be possessed thereof: for no man forgets what he knows naturally; that, for instance, the whole is larger than the part, and such like. And especially unreasonable does this seem if we suppose that it is natural to the soul to be united to the body, as we have established above (): for it is unreasonable that the natural operation of a thing be totally hindered by that which belongs to it naturally. Secondly, the falseness of this opinion is clearly proved from the fact that if a sense be wanting, the knowledge of what is apprehended through that sense is wanting also: for instance, a man who is born blind can have no knowledge of colors. This would not be the case if the soul had innate images of all intelligible things. We must therefore conclude that the soul does not know corporeal things through innate species.

Article 4: Whether the intelligible species are derived by the soul from certain separate forms?

If this were true we should not need the senses in order to understand. And this is proved to be false especially from the fact that if a man be wanting in a sense, he cannot have any knowledge of the sensibles corresponding to that sense.

Some have held that the intelligible species of our intellect are derived from certain separate forms or substances. And this in two ways. For Plato, as we have said (), held that the forms of sensible things subsist by themselves without matter; for instance, the form of a man which he called "per se" man, and the form or idea of a horse which is called "per se" horse, and so forth. He said therefore that these forms are participated both by our soul and by corporeal matter; by our soul, to the effect of knowledge thereof, and by corporeal matter to the effect of existence: so that, just as corporeal matter by participating the idea of a stone, becomes an individuating stone, so our intellect, by participating the idea of a stone, is made to understand a stone. Now participation of an idea takes place by some image of the idea in the participator, just as a model is participated by a copy. So just as he held that the sensible forms, which are in corporeal matter, are derived from the ideas as certain images thereof: so he held that the intelligible species of our intellect are images of the ideas, derived therefrom. And for this reason, as we have said above (), he referred sciences and definitions to those ideas.

But since it is contrary to the nature of sensible things that their forms should subsist without matter, as Aristotle proves in many ways (Metaph. vi), Avicenna (De Anima v) setting this opinion aside, held that the intelligible species of all sensible things, instead of subsisting in themselves without matter, pre-exist immaterially in the separate intellects: from the first of which, said he, such species are derived by a second, and so on to the last separate intellect which he called the "active intelligence," from which, according to him, intelligible species flow into our souls, and sensible species into corporeal matter. And so Avicenna agrees with Plato in this, that the intelligible species of our intellect are derived from certain separate forms; but these Plato held to subsist of themselves, while Avicenna placed them in the "active intelligence." They differ, too, in this respect, that Avicenna held that the intelligible species do not remain in our intellect after it has ceased actually to understand, and that it needs to turn (to the active intellect) in order to receive them anew. Consequently he does not hold that the soul has innate knowledge, as Plato, who held that the participated ideas remain immovably in the soul.

But in this opinion no sufficient reason can be assigned for the soul being united to the body. For it cannot be said that the intellectual soul is united to the body for the sake of the body: for neither is form for the sake of matter, nor is the mover for the sake of the moved, but rather the reverse. Especially does the body seem necessary to the intellectual soul, for the latter's proper operation which is to understand: since as to its being the soul does not depend on the body. But if the soul by its very nature had an inborn aptitude for receiving intelligible species through the influence of only certain separate principles, and were not to receive them from the senses, it would not need the body in order to understand: wherefore to no purpose would it be united to the body.

But if it be said that our soul needs the senses in order to understand, through being in some way awakened by them to the consideration of those things, the intelligible species of which it receives from the separate principles: even this seems an insufficient explanation. For this awakening does not seem necessary to the soul, except in as far as it is overcome by sluggishness, as the Platonists expressed it, and by forgetfulness, through its union with the body: and thus the senses would be of no use to the intellectual soul except for the purpose of removing the obstacle which the soul encounters through its union with the body. Consequently the reason of the union of the soul with the body still remains to be sought.

And if it be said with Avicenna, that the senses are necessary to the soul, because by them it is aroused to turn to the "active intelligence" from which it receives the species: neither is this a sufficient explanation. Because if it is natural for the soul to understand through species derived from the "active intelligence," it follows that at times the soul of an individual wanting in one of the senses can turn to the active intelligence, either from the inclination of its very nature, or through being roused by another sense, to the effect of receiving the intelligible species of which the corresponding sensible species are wanting. And thus a man born blind could have knowledge of colors; which is clearly untrue. We must therefore conclude that the intelligible species, by which our soul understands, are not derived from separate forms.

Article 5: Whether the intellectual soul knows material things in the eternal types?

Augustine says (Confess. xii, 25): "If we both see that what you say is true, and if we both see that what I say is true, where do we see this, I pray? Neither do I see it in you, nor do you see it in me: but we both see it in the unchangeable truth which is above our minds." Now the unchangeable truth is contained in the eternal types. Therefore the intellectual soul knows all true things in the eternal types.

As Augustine says (De Doctr. Christ. ii, 11): "If those who are called philosophers said by chance anything that was true and consistent with our faith, we must claim it from them as from unjust possessors. For some of the doctrines of the heathens are spurious imitations or superstitious inventions, which we must be careful to avoid when we renounce the society of the heathens." Consequently whenever Augustine, who was imbued with the doctrines of the Platonists, found in their teaching anything consistent with faith, he adopted it: and those thing which he found contrary to faith he amended. Now Plato held, as we have said above (), that the forms of things subsist of themselves apart from matter; and these he called ideas, by participation of which he said that our intellect knows all things: so that just as corporeal matter by participating the idea of a stone becomes a stone, so our intellect, by participating the same idea, has knowledge of a stone. But since it seems contrary to faith that forms of things themselves, outside the things themselves and apart from matter, as the Platonists held, asserting that "per se" life or "per se" wisdom are creative substances, as Dionysius relates (Div. Nom. xi); therefore Augustine (QQ. 83, qu. 46), for the ideas defended by Plato, substituted the types of all creatures existing in the Divine mind, according to which types all things are made in themselves, and are known to the human soul.

When, therefore, the question is asked: Does the human soul know all things in the eternal types? we must reply that one thing is said to be known in another in two ways. First, as in an object itself known; as one may see in a mirror the images of things reflected therein. In this way the soul, in the present state of life, cannot see all things in the eternal types; but the blessed who see God, and all things in Him, thus know all things in the eternal types. Secondly, on thing is said to be known in another as in a principle of knowledge: thus we might say that we see in the sun what we see by the sun. And thus we must needs say that the human soul knows all things in the eternal types, since by participation of these types we know all things. For the intellectual light itself which is in us, is nothing else than a participated likeness of the uncreated light, in which are contained the eternal types. Whence it is written (Ps. 4:6,7), "Many say: Who showeth us good things?" which question the Psalmist answers, "The light of Thy countenance, O Lord, is signed upon us," as though he were to say: By the seal of the Divine light in us, all things are made known to us.

But since besides the intellectual light which is in us, intelligible species, which are derived from things, are required in order for us to have knowledge of material things; therefore this same knowledge is not due merely to a participation of the eternal types, as the Platonists held, maintaining that the mere participation of ideas sufficed for knowledge. Wherefore Augustine says (De Trin. iv, 16): "Although the philosophers prove by convincing arguments that all things occur in time according to the eternal types, were they able to see in the eternal types, or to find out from them how many kinds of animals there are and the origin of each? Did they not seek for this information from the story of times and places?"

But that Augustine did not understand all things to be known in their "eternal types" or in the "unchangeable truth," as though the eternal types themselves were seen, is clear from what he says (QQ. 83, qu. 46)---viz. that "not each and every rational soul can be said to be worthy of that vision," namely, of the eternal types, "but only those that are holy and pure," such as the souls of the blessed.

From what has been said the objections are easily solved.

Article 6: Whether intellectual knowledge is derived from sensible things?

The Philosopher says (Metaph. i, 1; Poster. ii, 15) that the principle of knowledge is in the senses.

On this point the philosophers held three opinions. For Democritus held that "all knowledge is caused by images issuing from the bodies we think of and entering into our souls," as Augustine says in his letter to Dioscorus (cxviii, 4). And Aristotle says (De Somn. et Vigil.) that Democritus held that knowledge is cause by a "discharge of images." And the reason for this opinion was that both Democritus and the other early philosophers did not distinguish between intellect and sense, as Aristotle relates (De Anima iii, 3). Consequently, since the sense is affected by the sensible, they thought that all our knowledge is affected by this mere impression brought about by sensible things. Which impression Democritus held to be caused by a discharge of images.

Plato, on the other hand, held that the intellect is distinct from the senses: and that it is an immaterial power not making use of a corporeal organ for its action. And since the incorporeal cannot be affected by the corporeal, he held that intellectual knowledge is not brought about by sensible things affecting the intellect, but by separate intelligible forms being participated by the intellect, as we have said above (). Moreover he held that sense is a power operating of itself. Consequently neither is sense, since it is a spiritual power, affected by the sensible: but the sensible organs are affected by the sensible, the result being that the soul is in a way roused to form within itself the species of the sensible. Augustine seems to touch on this opinion (Gen. ad lit. xii, 24) where he says that the "body feels not, but the soul through the body, which it makes use of as a kind of messenger, for reproducing within itself what is announced from without." Thus according to Plato, neither does intellectual knowledge proceed from sensible knowledge, nor sensible knowledge exclusively from sensible things; but these rouse the sensible soul to the sentient act, while the senses rouse the intellect to the act of understanding.

Aristotle chose a middle course. For with Plato he agreed that intellect and sense are different. But he held that the sense has not its proper operation without the cooperation of the body; so that to feel is not an act of the soul alone, but of the "composite." And he held the same in regard to all the operations of the sensitive part. Since, therefore, it is not unreasonable that the sensible objects which are outside the soul should produce some effect in the "composite," Aristotle agreed with Democritus in this, that the operations of the sensitive part are caused by the impression of the sensible on the sense: not by a discharge, as Democritus said, but by some kind of operation. For Democritus maintained that every operation is by way of a discharge of atoms, as we gather from De Gener. i, 8. But Aristotle held that the intellect has an operation which is independent of the body's cooperation. Now nothing corporeal can make an impression on the incorporeal. And therefore in order to cause the intellectual operation according to Aristotle, the impression caused by the sensible does not suffice, but something more noble is required, for "the agent is more noble than the patient," as he says (De Gener. i, 5). Not, indeed, in the sense that the intellectual operation is effected in us by the mere intellectual operation is effected in us by the mere impression of some superior beings, as Plato held; but that the higher and more noble agent which he calls the active intellect, of which we have spoken above () causes the phantasms received from the senses to be actually intelligible, by a process of abstraction.

According to this opinion, then, on the part of the phantasms, intellectual knowledge is caused by the senses. But since the phantasms cannot of themselves affect the passive intellect, and require to be made actually intelligible by the active intellect, it cannot be said that sensible knowledge is the total and perfect cause of intellectual knowledge, but rather that it is in a way the material cause.

Article 7: Whether the intellect can actually understand through the intelligible species of which it is possessed, without turning to the phantasms?

The Philosopher says (De Anima iii, 7) that "the soul understands nothing without a phantasm."

In the present state of life in which the soul is united to a passible body, it is impossible for our intellect to understand anything actually, except by turning to the phantasms. First of all because the intellect, being a power that does not make use of a corporeal organ, would in no way be hindered in its act through the lesion of a corporeal organ, if for its act there were not required the act of some power that does make use of a corporeal organ. Now sense, imagination and the other powers belonging to the sensitive part, make use of a corporeal organ. Wherefore it is clear that for the intellect to understand actually, not only when it acquires fresh knowledge, but also when it applies knowledge already acquired, there is need for the act of the imagination and of the other powers. For when the act of the imagination is hindered by a lesion of the corporeal organ, for instance in a case of frenzy; or when the act of the memory is hindered, as in the case of lethargy, we see that a man is hindered from actually understanding things of which he had a previous knowledge. Secondly, anyone can experience this of himself, that when he tries to understand something, he forms certain phantasms to serve him by way of examples, in which as it were he examines what he is desirous of understanding. For this reason it is that when we wish to help someone to understand something, we lay examples before him, from which he forms phantasms for the purpose of understanding.

Now the reason of this is that the power of knowledge is proportioned to the thing known. Wherefore the proper object of the angelic intellect, which is entirely separate from a body, is an intelligible substance separate from a body. Whereas the proper object of the human intellect, which is united to a body, is a quiddity or nature existing in corporeal matter; and through such natures of visible things it rises to a certain knowledge of things invisible. Now it belongs to such a nature to exist in an individual, and this cannot be apart from corporeal matter: for instance, it belongs to the nature of a stone to be in an individual stone, and to the nature of a horse to be in an individual horse, and so forth. Wherefore the nature of a stone or any material thing cannot be known completely and truly, except in as much as it is known as existing in the individual. Now we apprehend the individual through the senses and the imagination. And, therefore, for the intellect to understand actually its proper object, it must of necessity turn to the phantasms in order to perceive the universal nature existing in the individual. But if the proper object of our intellect were a separate form; or if, as the Platonists say, the natures of sensible things subsisted apart from the individual; there would be no need for the intellect to turn to the phantasms whenever it understands.

Article 8: Whether the judgment of the intellect is hindered through suspension of the sensitive powers?

What a man does while asleep, against the moral law, is not imputed to him as a sin; as Augustine says (Gen. ad lit. xii, 15). But this would not be the case if man, while asleep, had free use of his reason and intellect. Therefore the judgment of the intellect is hindered by suspension of the senses.

As we have said above (), our intellect's proper and proportionate object is the nature of a sensible thing. Now a perfect judgment concerning anything cannot be formed, unless all that pertains to that thing's nature be known; especially if that be ignored which is the term and end of judgment. Now the Philosopher says (De Coel. iii), that "as the end of a practical science is action, so the end of natural science is that which is perceived principally through the senses"; for the smith does not seek knowledge of a knife except for the purpose of action, in order that he may produce a certain individual knife; and in like manner the natural philosopher does not seek to know the nature of a stone and of a horse, save for the purpose of knowing the essential properties of those things which he perceives with his senses. Now it is clear that a smith cannot judge perfectly of a knife unless he knows the action of the knife: and in like manner the natural philosopher cannot judge perfectly of natural things, unless he knows sensible things. But in the present state of life whatever we understand, we know by comparison to natural sensible things. Consequently it is not possible for our intellect to form a perfect judgment, while the senses are suspended, through which sensible things are known to us.