Summa contra Gentiles2.13 Chapter XIII and XIV. How the aforesaid relations are predicated of God

Nevertheless it cannot be said that the aforesaid relations exist extraneously as something outside God.

For since God is the first being and sovereign good, it would be necessary to consider yet other relations of God to those relations that are realities. And if these also are realities, we shall again have to find third relations: and so on indefinitely. Therefore the relations by which God is referred to other things are not really existing outside God.

Again. A thing is predicated denominatively in two ways. For a thing may be denominated from that which is outside it; for instance from place a person is said to be Bk. I., ch. Ixxxii. * Ch. xiii. xli.

somewhere, and from time somewhen: and a thing may be denominated from that which is in it, as a person is denominated white from whiteness. On the other hand a thing is not found to be denominated from a relation as extraneous, but as inherent: for a man is not denominated a father except from fatherhood which is in him. Therefore it is impossible for the relations whereby God is referred to creatures to be realities outside Him.

Since then it has been proved that they are not really in Him, and yet are predicated of Him, it remains that they are ascribed to Him according only to our way of understanding, from the fact that other things are referred to Him. For our intellect, in understanding one thing to be referred to another, understands at the same time that the latter is related to the former; although sometimes it is not really related at all.

Wherefore it is also evident that the aforesaid relations are not said of God in the same way as other things predicated of God. For all other things, as wisdom, will, predicate His essence, whereas the aforesaid relations do not by any means, but solely according to our way of understanding. And yet our understanding is not false. Because from the very fact that our intellect understands that the relations of the divine effects terminate in God Himself, it predicates certain things of Him relatively: even so we understand and express the knowable relatively from the fact that our knowledge is referred to it.

It is also clear from the foregoing that it is not prejudicial to God’s simplicity if many relations are predicated of Him, although they do not signify His essence: because they are consequent upon our way of understanding. For nothing hinders our intellect understanding many things, and being referred in many ways to that which is in itself simple, so as thus to consider the simple thing under a manifold relationship. And the more simple a thing is, the greater its virtue, and of so many more things is it a principle, and consequently it is understood as related in so many more ways: thus a point is a principle of more things than a line is, and a line of more things than a surface. Wherefore the very fact that many things are said of God relatively, bears witness to His supreme simplicity.