Summa Theologica Part I (Prima Pars) Part 134

_I answer that,_ We must apply the same distinction to future things, as we applied above (A. 3) to contingent things. For future things considered as subject to time are singular, and the human intellect knows them by reflection only, as stated above (A. 1). But the principles of future things may be universal; and thus they may enter the domain of the intellect and become the objects of science.

Speaking, however, of the knowledge of the future in a general way, we must observe that the future may be known in two ways: either in itself, or in its cause. The future cannot be known in itself save by G.o.d alone; to Whom even that is present which in the course of events is future, forasmuch as from eternity His glance embraces the whole course of time, as we have said above when treating of G.o.d's knowledge (Q. 14, A. 13). But forasmuch as it exists in its cause, the future can be known by us also. And if, indeed, the cause be such as to have a necessary connection with its future result, then the future is known with scientific cert.i.tude, just as the astronomer foresees the future eclipse. If, however, the cause be such as to produce a certain result more frequently than not, then can the future be known more or less conjecturally, according as its cause is more or less inclined to produce the effect.

Reply Obj. 1: This argument considers that knowledge which is drawn from universal causal principles; from these the future may be known, according to the order of the effects to the cause.

Reply Obj. 2: As Augustine says (Confess. xii [*Gen. ad lit. xii.

13]), the soul has a certain power of forecasting, so that by its very nature it can know the future; hence when withdrawn from corporeal sense, and, as it were, concentrated on itself, it shares in the knowledge of the future. Such an opinion would be reasonable if we were to admit that the soul receives knowledge by partic.i.p.ating the ideas as the Platonists maintained, because in that case the soul by its nature would know the universal causes of all effects, and would only be impeded in its knowledge by the body, and hence when withdrawn from the corporeal senses it would know the future.

But since it is connatural to our intellect to know things, not thus, but by receiving its knowledge from the senses; it is not natural for the soul to know the future when withdrawn from the senses: rather does it know the future by the impression of superior spiritual and corporeal causes; of spiritual causes, when by Divine power the human intellect is enlightened through the ministry of angels, and the phantasms are directed to the knowledge of future events; or, by the influence of demons, when the imagination is moved regarding the future known to the demons, as explained above (Q. 57, A. 3). The soul is naturally more inclined to receive these impressions of spiritual causes when it is withdrawn from the senses, as it is then nearer to the spiritual world, and freer from external distractions.

The same may also come from superior corporeal causes. For it is clear that superior bodies influence inferior bodies. Hence, in consequence of the sensitive faculties being acts of corporeal organs, the influence of the heavenly bodies causes the imagination to be affected, and so, as the heavenly bodies cause many future events, the imagination receives certain images of some such events.

These images are perceived more at night and while we sleep than in the daytime and while we are awake, because, as stated in _De Somn.

et Vigil._ ii [*De Divinat. per somn. ii], "impressions made by day are evanescent. The night air is calmer, when silence reigns, hence bodily impressions are made in sleep, when slight internal movements are felt more than in wakefulness, and such movements produce in the imagination images from which the future may be foreseen."

Reply Obj. 3: Brute animals have no power above the imagination wherewith to regulate it, as man has his reason, and therefore their imagination follows entirely the influence of the heavenly bodies.

Thus from such animals' movements some future things, such as rain and the like, may be known rather than from human movements directed by reason. Hence the Philosopher says (De Somn. et Vig.), that "some who are most imprudent are most far-seeing; for their intelligence is not burdened with cares, but is as it were barren and bare of all anxiety moving at the caprice of whatever is brought to bear on it."

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QUESTION 87

HOW THE INTELLECTUAL SOUL KNOWS ITSELF AND ALL WITHIN ITSELF (In Four Articles)

We have now to consider how the intellectual soul knows itself and all within itself. Under this head there are four points of inquiry:

(1) Whether the soul knows itself by its own essence?

(2) Whether it knows its own habits?

(3) How does the intellect know its own act?

(4) How does it know the act of the will?

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FIRST ARTICLE [I, Q. 87, Art. 1]

Whether the Intellectual Soul Knows Itself by Its Essence?

Objection 1: It would seem that the intellectual soul knows itself by its own essence. For Augustine says (De Trin. ix, 3), that "the mind knows itself, because it is incorporeal."

Obj. 2: Further, both angels and human souls belong to the genus of intellectual substance. But an angel understands itself by its own essence. Therefore likewise does the human soul.

Obj. 3: Further, "in things void of matter, the intellect and that which is understood are the same" (De Anima iii, 4). But the human mind is void of matter, not being the act of a body as stated above (Q. 76, A. 1). Therefore the intellect and its object are the same in the human mind; and therefore the human mind understands itself by its own essence.

_On the contrary,_ It is said (De Anima iii, 4) that "the intellect understands itself in the same way as it understands other things."

But it understands other things, not by their essence, but by their similitudes. Therefore it does not understand itself by its own essence.

_I answer that,_ Everything is knowable so far as it is in act, and not, so far as it is in potentiality (Metaph. ix, Did. viii, 9): for a thing is a being, and is true, and therefore knowable, according as it is actual. This is quite clear as regards sensible things, for the eye does not see what is potentially, but what is actually colored.

In like manner it is clear that the intellect, so far as it knows material things, does not know save what is in act: and hence it does not know primary matter except as proportionate to form, as is stated Phys. i, 7. Consequently immaterial substances are intelligible by their own essence according as each one is actual by its own essence.

Therefore it is that the Essence of G.o.d, the pure and perfect act, is simply and perfectly in itself intelligible; and hence G.o.d by His own Essence knows Himself, and all other things also. The angelic essence belongs, indeed, to the genus of intelligible things as _act,_ but not as a _pure act,_ nor as a _complete act,_ and hence the angel's act of intelligence is not completed by his essence. For although an angel understands himself by his own essence, still he cannot understand all other things by his own essence; for he knows things other than himself by their likenesses. Now the human intellect is only a potentiality in the genus of intelligible beings, just as primary matter is a potentiality as regards sensible beings; and hence it is called "possible" [*Possibilis--elsewhere in this translation rendered "pa.s.sive"--Ed.]. Therefore in its essence the human mind is potentially understanding. Hence it has in itself the power to understand, but not to be understood, except as it is made actual. For even the Platonists a.s.serted that an order of intelligible beings existed above the order of intellects, forasmuch as the intellect understands only by partic.i.p.ation of the intelligible; for they said that the partic.i.p.ator is below what it partic.i.p.ates. If, therefore, the human intellect, as the Platonists held, became actual by partic.i.p.ating separate intelligible forms, it would understand itself by such partic.i.p.ation of incorporeal beings.

But as in this life our intellect has material and sensible things for its proper natural object, as stated above (Q. 84, A. 7), it understands itself according as it is made actual by the species abstracted from sensible things, through the light of the active intellect, which not only actuates the intelligible things themselves, but also, by their instrumentality, actuates the pa.s.sive intellect. Therefore the intellect knows itself not by its essence, but by its act. This happens in two ways: In the first place, singularly, as when Socrates or Plato perceives that he has an intellectual soul because he perceives that he understands. In the second place, universally, as when we consider the nature of the human mind from knowledge of the intellectual act. It is true, however, that the judgment and force of this knowledge, whereby we know the nature of the soul, comes to us according to the derivation of our intellectual light from the Divine Truth which contains the types of all things as above stated (Q. 84, A. 5). Hence Augustine says (De Trin. ix, 6): "We gaze on the inviolable truth whence we can as perfectly as possible define, not what each man's mind is, but what it ought to be in the light of the eternal types." There is, however, a difference between these two kinds of knowledge, and it consists in this, that the mere presence of the mind suffices for the first; the mind itself being the principle of action whereby it perceives itself, and hence it is said to know itself by its own presence. But as regards the second kind of knowledge, the mere presence of the mind does not suffice, and there is further required a careful and subtle inquiry. Hence many are ignorant of the soul's nature, and many have erred about it. So Augustine says (De Trin. x, 9), concerning such mental inquiry: "Let the mind strive not to see itself as if it were absent, but to discern itself as present"--i.e.

to know how it differs from other things; which is to know its essence and nature.

Reply Obj. 1: The mind knows itself by means of itself, because at length it acquires knowledge of itself, though led thereto by its own act: because it is itself that it knows, since it loves itself, as he says in the same pa.s.sage. For a thing can be called self-evident in two ways, either because we can know it by nothing else except itself, as first principles are called self-evident; or because it is not accidentally knowable, as color is visible of itself, whereas substance is visible by its accident.

Reply Obj. 2: The essence of an angel is an act in the genus of intelligible things, and therefore it is both intellect and the thing understood. Hence an angel apprehends his own essence through itself: not so the human mind, which is either altogether in potentiality to intelligible things--as is the pa.s.sive intellect--or is the act of intelligible things abstracted from the phantasms--as is the active intellect.

Reply Obj. 3: This saying of the Philosopher is universally true in every kind of intellect. For as sense in act is the sensible in act, by reason of the sensible likeness which is the form of sense in act, so likewise the intellect in act is the object understood in act, by reason of the likeness of the thing understood, which is the form of the intellect in act. So the human intellect, which becomes actual by the species of the object understood, is itself understood by the same species as by its own form. Now to say that in "things without matter the intellect and what is understood are the same," is equal to saying that "as regards things actually understood the intellect and what is understood are the same." For a thing is actually understood in that it is immaterial. But a distinction must be drawn: since the essences of some things are immaterial--as the separate substances called angels, each of which is understood and understands, whereas there are other things whose essences are not wholly immaterial, but only the abstract likenesses thereof. Hence the Commentator says (De Anima iii) that the proposition quoted is true only of separate substances; because in a sense it is verified in their regard, and not in regard of other substances, as already stated (Reply Obj. 2).

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SECOND ARTICLE [I, Q. 87, Art. 2]

Whether Our Intellect Knows the Habits of the Soul by Their Essence?

Objection 1: It would seem that our intellect knows the habits of the soul by their essence. For Augustine says (De Trin. xiii, 1): "Faith is not seen in the heart wherein it abides, as the soul of a man may be seen by another from the movement of the body; but we know most certainly that it is there, and conscience proclaims its existence"; and the same principle applies to the other habits of the soul.

Therefore the habits of the soul are not known by their acts, but by themselves.

Obj. 2: Further, material things outside the soul are known by their likeness being present in the soul, and are said therefore to be known by their likenesses. But the soul's habits are present by their essence in the soul. Therefore the habits of the soul are known by their essence.

Obj. 3: Further, "whatever is the cause of a thing being such is still more so." But habits and intelligible species cause things to be known by the soul. Therefore they are still more known by the soul in themselves.

_On the contrary,_ Habits like powers are the principles of acts. But as is said (De Anima ii, 4), "acts and operations are logically prior to powers." Therefore in the same way they are prior to habits; and thus habits, like the powers, are known by their acts.

_I answer that,_ A habit is a kind of medium between mere power and mere act. Now, it has been said (A. 1) that nothing is known but as it is actual: therefore so far as a habit fails in being a perfect act, it falls short in being of itself knowable, and can be known only by its act; thus, for example, anyone knows he has a habit from the fact that he can produce the act proper to that habit; or he may inquire into the nature and idea of the habit by considering the act.

The first kind of knowledge of the habit arises from its being present, for the very fact of its presence causes the act whereby it is known. The second kind of knowledge of the habit arises from a careful inquiry, as is explained above of the mind (A. 1).

Reply Obj. 1: Although faith is not known by external movement of the body, it is perceived by the subject wherein it resides, by the interior act of the heart. For no one knows that he has faith unless he knows that he believes.

Reply Obj. 2: Habits are present in our intellect, not as its object since, in the present state of life, our intellect's object is the nature of a material thing as stated above (Q. 84, A. 7), but as that by which it understands.

Reply Obj. 3: The axiom, "whatever is the cause of a thing being such, is still more so," is true of things that are of the same order, for instance, of the same kind of cause; for example, we may say that health is desirable on account of life, and therefore life is more desirable still. But if we take things of different orders the axiom is not true: for we may say that health is caused by medicine, but it does not follow that medicine is more desirable than health, for health belongs to the order of final causes, whereas medicine belongs to the order of efficient causes. So of two things belonging essentially to the order of the objects of knowledge, the one which is the cause of the other being known, is the more known, as principles are more known than conclusions. But habit as such does not belong to the order of objects of knowledge; nor are things known on account of the habit, as on account of an object known, but as on account of a disposition or form whereby the subject knows: and therefore the argument does not prove.

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THIRD ARTICLE [I, Q. 87, Art. 3]

Whether Our Intellect Knows Its Own Act?

Objection 1: It would seem that our intellect does not know its own act. For what is known is the object of the knowing faculty. But the act differs from the object. Therefore the intellect does not know its own act.

Obj. 2: Further, whatever is known is known by some act. If, then, the intellect knows its own act, it knows it by some act, and again it knows that act by some other act; this is to proceed indefinitely, which seems impossible.

Obj. 3: Further, the intellect has the same relation to its act as sense has to its act. But the proper sense does not feel its own act, for this belongs to the common sense, as stated _De Anima_ iii, 2.

Therefore neither does the intellect understand its own act.

_On the contrary,_ Augustine says (De Trin. x, 11), "I understand that I understand."

_I answer that,_ As stated above (AA. 1, 2) a thing is intelligible according as it is in act. Now the ultimate perfection of the intellect consists in its own operation: for this is not an act tending to something else in which lies the perfection of the work accomplished, as building is the perfection of the thing built; but it remains in the agent as its perfection and act, as is said _Metaph._ ix, Did. viii, 8. Therefore the first thing understood of the intellect is its own act of understanding. This occurs in different ways with different intellects. For there is an intellect, namely, the Divine, which is Its own act of intelligence, so that in G.o.d the understanding of His intelligence, and the understanding of His Essence, are one and the same act, because His Essence is His act of understanding. But there is another intellect, the angelic, which is not its own act of understanding, as we have said above (Q. 79, A. 1), and yet the first object of that act is the angelic essence.

Wherefore although there is a logical distinction between the act whereby he understands that he understands, and that whereby he understands his essence, yet he understands both by one and the same act; because to understand his own essence is the proper perfection of his essence, and by one and the same act is a thing, together with its perfection, understood. And there is yet another, namely, the human intellect, which neither is its own act of understanding, nor is its own essence the first object of its act of understanding, for this object is the nature of a material thing. And therefore that which is first known by the human intellect is an object of this kind, and that which is known secondarily is the act by which that object is known; and through the act the intellect itself is known, the perfection of which is this act of understanding. For this reason did the Philosopher a.s.sert that objects are known before acts, and acts before powers (De Anima ii, 4).