Commentaria in Summam contra Gentiles, Liber I

Having shown that truth is in God, it is now shown that He is His own truth¹. I. And it is proved first as follows. God's understanding is the divine essence. Therefore also truth. — The consequence is proved: because truth is the perfection of the intellectual operation. But this is not perfected by anything supervening, just as divine esse is not, but is perfect of itself. Therefore, if understanding is the divine substance, truth too is the divine substance. Note that the true is the perfection of the intellectual operation as its terminus, since it is the concept of the intellect with adequation to the thing understood. In the divine intellect, however, there is no concept distinct from the very act of understanding, but it is the divine essence itself understood as the proper ratio of each thing. On this account the perfection of the divine intellect, which is truth, is not distinguished from the act of understanding itself. From this it follows that truth does not signify in its ratio only a relation of adequation: — neither a relation of reason, I say, because then God would not be truth, since He is not a being of reason; nor a real one, because there is no real relation of God to a creature: — but it signifies something absolute together with a relation. And God is truth with respect to the absolute that is signified, namely with respect to the likeness understood, but not with respect to the connoted relation. Second. God is His own goodness. Therefore also His own truth: because truth is the goodness of the intellect, as was said above². Third. Nothing in God can be said participatively, since He is His own esse. Therefore, since truth is in God, God is essentially truth. Fourth. Truth, although it is posited in the intellect, is nevertheless also in the thing: according to what Avicenna says, that the truth of a thing is a property of its esse which has been established for it; and this insofar as the thing is apt of itself to produce a true estimation in the intellect, and insofar as it imitates its own proper ratio, which is in the divine mind. But God is His own essence. Therefore He is His own truth, whether we speak of the truth of the intellect or of the truth of the thing. II. Note, from the doctrine of St. Thomas in the First Part³ and in the Questions on Truth⁴, that things are called true both in comparison to the divine intellect and in comparison to the human intellect. To the divine intellect indeed, insofar as they imitate their form existing in the divine mind: just as artificial things are said to be true insofar as they imitate the form of the art existing in the mind of the craftsman. And according to this comparison things are said to be true simply and absolutely, because they depend upon the divine intellect for their esse. — In comparison to the human intellect, namely the speculative, on which they do not depend, they are said to be true insofar as they are apt of themselves to produce a true estimation in that intellect. And thus they are said to be true in a certain respect, because they have no relation to the human intellect except per accidens, since they do not depend upon it. From these points it follows that, just as the truth of the intellect signifies two things, namely the absolute and the relation, or the material and the formal, so too does the truth of the thing. The absolute is the esse or entity of the thing; the relation, however, is the habitude to the intellect. But if it be asked whether these relations are real or of reason: it is said that the relation to the divine intellect is real, because it is the relation of what is measured to the measure; for the divine intellect is the measure of all things, just as the intellect of the craftsman is the measure of the things crafted. But the relation to the human speculative intellect is a relation of reason, because it is that of the measure to what is measured: for the truth of our intellect is measured by the thing itself, for an intellect is said to be true because it understands as the thing is. It should also be known that, although truth is in some way in the thing, yet that is improperly called truth, since truth is first and per se in the intellect. Hence, speaking simply and properly, a thing is not said to be true except by extrinsic denomination, namely from the truth of the intellect. From a form existing in itself, however, it is said to be true intrinsically, but improperly: just as medicine is properly said to be healthy from the health existing in an animal, but improperly from the power existing in it. Therefore St. Thomas concluded that, whether we speak of the truth of the intellect or of the truth of the thing, God is His own truth, since He is His own essence. Because if we take truth improperly, from which a thing is indeed said to be true intrinsically, it is nothing other than the very substance of the thing, or its esse. Therefore, if God is His own essence, it follows that He is His own truth. If we also take the truth of the thing from which a thing is properly denominated true, though extrinsically, which is the truth of the intellect, it was likewise said that this is the very essence of God. Therefore, however a thing may be said to be true, it follows that God is His own truth. The conclusion is confirmed by the authority of John xiv, I am the way, the truth, and the life.