Commentaria in Summam contra Gentiles, Liber I

The fourth conclusion, answering the fourth objection, is: God knows the thoughts of minds and the wills of hearts ¹.

For the understanding of which it should be noted that, because the heart is the principle of motion in animals among bodily movers, therefore the motions of the will are said to be motions of the heart by way of similitude: for the will itself is simply the first principle of motion. Or they are also called motions of hearts on account of their hiddenness: for one man's motions of will are hidden from another, just as are the affections of his heart. Therefore by "wills of hearts" he understands affections of the will; and by "thoughts of minds," acts of the intellect.

I. The conclusion is first proved. God knows being in the soul and being outside the soul. Therefore He knows those things that are in the will and in thought. — The antecedent is evident. For, as was said above, everything that exists in any way is known by God, insofar as He knows His own essence. Now some being is in the soul and some is outside the soul. — But the consequence is proved. For being in the soul is what is in thought and in the will.

Note that the acts of intellect and will can be considered in two ways: in one way, absolutely, as accidents of the soul; in another way, as terminated to objects. Since, therefore, God not only knows the very substance of those acts, but also beholds to which objects those acts are terminated, he concludes that God knows the things that are in thought and will—namely, the objects themselves insofar as they terminate the acts of intellect and will—which is to know those acts themselves as terminated to objects. – Although this could also be understood of the acts themselves, and not immediately of the objects. For he knows the acts themselves existing in the soul; and because they cannot be perfectly known unless it is known to which objects they are terminated, since they are specified by them, therefore it is necessary that God also know the objects to which they are terminated.

II. Second. God's causality extends to the operations of intellect and will. Therefore also to God's knowledge. — The consequence is evident, because God, in knowing His own essence, knows all things to which His causality extends. — The antecedent, however, is proved as follows: God is the fountal principle of all esse, from which every form is. Therefore He is the principle of every operation. The consequence is evident, because every thing operates through the form from which the esse of the thing is; but the effects of causes are reduced more principally to the first causes; therefore every operation of whatever form is reduced to the first cause of every form.

III. Third. The divine understanding is first, and consequently the cause of every intellectual operation, just as its esse is first and the cause of all esse. Therefore, by knowing its own understanding and its own willing, it knows every thought and every act of will. — The consequence is evident. For likewise, by knowing its own esse, it knows the esse of any thing whatsoever.

Note that, just as the divine esse is the exemplary cause of all esse, but not properly its efficient cause, if it is taken formally as distinct from the other attributes, so understanding as understanding—that is, by way of immanent act—and likewise willing, as is taught by Saint Thomas in the First Part, d. XXXVIII, a. 1, have the character of the exemplary cause of all understanding and all willing: because every act of understanding and willing is a certain participation in the divine intellection and volition.

IV. Fourth. God knows things not only as they are in themselves, but also as they are in their causes, since He knows the order of cause to effect. Therefore, etc. — The consequence is proved: because just as natural things are in their causes through the powers of those causes, so things made by art are in the artisans through the intellect and will of the artisans, since the artisan produces in the thing made a form by which it is assimilated to his art. And it is likewise in all things that are done from deliberate purpose.

It must be noted that it is common to every agent to produce an effect similar to the form by which it acts. Therefore, since an agent acting from intention acts through a conception of its intellect joined with the will, it is necessary that in the effect there be produced a form similar to the conception and intention of the agent: not indeed similar to the act of conceiving, but similar to the form conceived, at least according to some unity of reason, even if not according to the same mode of being. The sign, therefore, that an agent acts from intention through intellect and will is that it produces an effect similar to its conception and volition. And therefore God, who knows the effect insofar as it is in the disposition of the cause, knows the act of intellect and of will, through which an agent is disposed from intention to acting.

V. Fifth. The informations and inclinations of natural things are known by God and by us. Therefore God also knows the informations and inclinations of the soul. Therefore thoughts and affections. – The first inference is proved: because God knows intellectual substances no less than He Himself or we know sensible substances, since intellectual substances are more knowable, as being more in act. – The second is also proved: because a thought of the soul occurs through a certain information of it; an affection, however, is a certain inclination of it toward something, whence we also call the inclination of a natural thing its natural appetite.

Two things are to be noted here. The first is that from the fact that God knows the information of sensible things, it follows that He also knows the information of intellectual things; but this does not follow in our case. For the more certain things are intelligible in themselves, the more they are known by the divine intellect, which is maximally in act; whereas the most intelligible things are least known by us, on account of the imperfection of our intellect. And therefore, if sensible things are known by God, much more are intelligible things known by Him; but it is not the case that, because we know sensible and material things, we must therefore understand intelligible things more.

The second is what Saint Thomas said, namely that the thought of the soul is by a certain informing of it, but affection by an inclination. This must not be understood as though thought informed the soul, but affection did not — indeed, since each denotes an immanent act, the soul is informed by both; rather, the point is that thought comes about through the fact that the understood object in some way informs the soul, whereas affection comes about through the fact that the soul is inclined toward the thing itself outside the soul. For truth, which pertains to the intellect, is in the soul, as is said in Book VI of the Metaphysics ²; but good, which pertains to the will, is in things. And thus God knows the thought, according to which the soul is informed by the concept and word of the intellect, and the inclination of the will toward an external thing.

The conclusion is confirmed by the authority of the Psalm, and Prov. xv, and Ioan. II.

VI. But to the objection on the opposite side ³, which consists in this: because the act of the will is in the power of the will, therefore it can be known by the one willing alone — it is answered that to will and not to will being in the power of the will indeed excludes determination to one thing, and violence from an extrinsic moving cause; but it does not exclude the influence of a superior cause, from which it has its esse and its acting. Therefore that consequence is denied: The act of the will is in the power of the will; therefore it is known by the one willing alone.