Summa contra Gentiles1.36 Chapter XXXVI. How our intellect forms a proposition about God

From this it is moreover clear that our intellect does not vainly form propositions about a simple God by composition and division, although God is altogether simple.

For although our intellect arrives at the knowledge of God by various conceptions, as stated above, it understands that what corresponds to them all is absolutely one: because our intellect does not ascribe its mode of understanding to the things which it understands, even as neither does it ascribe immateriality to a stone, although it knows it immaterially. Consequently it enunciates the unity of the thing by a verbal composition implying identity, when it says: God is good or is goodness: so that if there be any diversity in the composition it is referred to the understanding, and unity to the thing understood. Similarly sometimes our intellect forms a proposition about God with an implication of diversity by inserting a preposition, as when we say: Goodness is in God: because here we imply both a certain diversity that is befitting the understanding, and a certain unity which must be referred to the thing.