Commentaria in Summam contra Gentiles, Liber I

Since it has been shown that there is some first being, which we call God, Saint Thomas begins to investigate its simplicity and what it is, in the manner possible for us, in ¹. But because it is foolish to seek at once both knowledge and the way of knowing, as is said in II Metaphysics, ², therefore in this chapter he declares how we ought to investigate the divine substance; in the following chapters, however, he inquires into its conditions.

I. The conclusion, therefore, of this chapter is: In the consideration of the divine substance we must proceed chiefly by the way of remotion. For the understanding of this conclusion, it must be noted that, since above, in ³ the question was raised concerning the esse of God, and it was demonstrated that this proposition which we form about God, saying God is, is true, there remained the consideration of the quiddity and substance; for the question what a thing is follows the question whether it is ⁴. But because the quiddity and substance of God is not known in the same way as the quiddities of other things, especially natural things, since those can be known perfectly, but not the essence of God; therefore, after the knowledge of whether it is, the question is indeed raised concerning the what of God, but not concerning what it is, rather concerning what it is not. The sense of the conclusion, then, is that in knowing the divine substance and the what of God, the chief mode of knowledge is that we proceed by knowing what it is not, and not what it is. — He adds, moreover, chiefly, in order to show that the divine substance can indeed be known in some way by other means as well, namely by the way of causality and of eminence, which he himself treats, following the mind of Dionysius, in Super Boet. De Trin., q. 1, a. 2, and in I Sent., d. 35, a. 1; yet this way is the more fitting and easier for us.

II. He proves the conclusion, however, by supposing, as he gives us to understand, that our intellect knows the natures and substances of things through intelligible species. Then he argues as follows. The more we can remove from a thing by the intellect, the closer we approach to knowledge of its what-it-is. But we cannot know the what-it-is of God. Therefore, and so on.

He proves the greater. Something is known the more perfectly the more we behold its differences in a plurality of respects, since each thing has within itself its own proper esse distinct from all others. Now something is known the more perfectly the more fully is comprehended its esse—that is, the essence—to which esse is owed.

It is also evident from the manner of defining. For when we seek the definition of a thing, we first place it in some genus, then add the differentiae by which it is distinguished from other things. But when we cannot know what it is affirmatively, we contemplate its differentiae from other things through negations and removals. Therefore, and so on.

He proves the minor premise. Our intellect can know quidditatively only those things whose quiddities are represented through the intelligible forms it possesses. But the forms of our intellect cannot represent the divine substance and quiddity, since every form of our intellect is exceeded by its immensity, as will be explained below ⁵ Therefore, etc.

He then adds the mode of proceeding in negative differences of this kind, saying that just as in affirmative propositions one difference contracts another and draws nearer to the complete designation and definition of a thing by making it differ from more things, so too in negatives. Hence there will then be a proper consideration of God when He is known through negations of this kind as distinct from all things: although even thus knowledge of Him is not perfect.

Finally, he concludes that the starting point of such consideration is to be taken to be that God is altogether immovable. And although this has been shown above, he makes it manifest by the authorities of Scripture: namely, Malachi 3, where it is said, "I am God and I do not change"; likewise James 1, "With whom there is no alteration"; and also Numbers 23, "God is not as a man, that He should change".

III. For the clarification of this argument, it must be known that, although negation does not pertain intrinsically to the essence of a thing, and although a thing's substance as it is in itself is not known through negations known about it, nevertheless that mode of knowing serves to draw near to a proper knowledge of the thing's nature, because negation restricts the nature of the thing known. For if I say of something that it is a substance—and substance is divided into corporeal and incorporeal—once it is known that the thing is not an incorporeal substance, the thing known is restricted to corporeal substance. And since this is divided into sensible and insensible, once it is known that the thing is not insensible, it is restricted to sensible nature. And so on successively. Hence the holy Doctor rightly says that one negative difference is contracted by another: namely, because the more things are denied of a thing, the more limited the thing remains.

IV. But against the conclusion and the argument one can argue from what Scotus says, II Metaphysics, first. A negation cannot be known except through an affirmation. For, as is said in IV Metaphysics, text 16 ⁶, the affirmation is better known than the opposite negation. Therefore, if we cannot know what something is, neither will we be able to know what it is not.

Second, from the Philosopher, II Periherm. ⁷ Good is not evil because this affirmative is true: Good is good. Therefore, if we know what is not God, we first know what is. Therefore one must not proceed by the way of remotion.

Confirmed. For Saint Thomas, Potentia, q. VII, a. 5, says that, since every negation is proved by an affirmation, unless the human intellect knew something of God affirmatively, we could deny nothing of God.

V. For the solution of these points, it must be considered that, although not every negation, speaking absolutely, is founded upon a real affirmation—since, as is said in the Categories ⁸, not sitting is said both of what is and of what is not—nevertheless a negation said of some real being is always founded upon something existing in reality which does not admit along with itself what is negated; as Saint Thomas says in the First Part of the Second Part, q. LXXII, a. 6, and in On the Power, where above ⁹, likewise in the Commentary on the Sentences, d. XXXV, 1, ad 2. For man is not an ass because his nature is such that it does not admit the nature of an ass. And an Ethiopian is not white because he has blackness, which does not admit whiteness along with itself.

Since, then, a negation said of God is said of something that exists, it must be grounded upon something existing in God. Yet, although this is so, it is not necessary that one who knows a negation of God thereby know determinately and distinctly in Him the affirmation upon which it is grounded: for some negation concerning Him can be known, and yet the affirmation that is its foundation remain unknown. For someone can know that God is not an ass, and yet not know distinctly in Him that nature which is incompatible with the nature of an ass: just as someone can know that a cloth is not white, and yet not know distinctly what that color of the cloth is which is incompatible with whiteness.

Even if our intellect were to know all the affirmations on which the negations said of God have their foundation, still what he is would not be known: since the divine essence is of infinite perfection, which cannot be sufficiently explicated through those known affirmations.

Given also that God's quod quid est were known through those means, it would still be useful to employ the way of remotion. For we cannot ascend to a comprehension of those things that are most excellent, and which can be known by us only through inadequate effects, with such ease and security as when we first remove from the effects themselves their imperfection—since the effects fall far short of their perfection—and so are raised to some knowledge of them.

VI. To the first ¹⁰ it is therefore said that the antecedent is false concerning the affirmation upon which the negation is founded. — In reply to the proof it is said that indeed affirmation in itself, insofar as it is affirmation, is better known than negation as negation: yet not with respect to us.

In confirmation it is said that it is not the mind of St. Thomas that we must first know the affirmation upon which a negation said of God is founded, before the negation itself; but rather that, since a negative is proved by an affirmative in itself, that being about which a negation is formed as about some being must be known with respect to some affirmative predicate; otherwise we would not know that such a negation is said of a being. And thus, if we must deny something of God as of a being, it is necessary that we know something of him affirmatively. With this, however, it stands that one who knows something of God negatively need not first know the affirmation upon which the said negation is founded. For it suffices that something be known affirmatively of him in order that we may know that there is in him some foundation for a negation; for this would not be known unless we knew him to be some being in nature, and consequently unless we knew some affirmative predicate of him. For where the essence of a thing cannot be comprehended as it is in itself, as will be shown below concerning the divine substance ¹¹, a negation can be more known to us than an affirmation, and the affirmation known through the negation.

To the second, the consequence is denied. For even given that negation is founded in affirmation, it does not follow that affirmation is known first, speaking universally; but rather, on the contrary, sometimes affirmation is known from negation, as was said in reply to the first.