5. According to the order of objects is the order and distinction of powers: therefore above all sensible objects there is some intelligible object, existing in the nature of things. But every corporeal thing existing in nature is sensible: therefore there is determinable above all corporeal things something nobler than they. If therefore God is corporeal, He is not the first and greatest Being.* With this demonstrated truth divine authority also agrees. For it is said: God is a spirit (John iv, 24): To the King of ages, immortal, invisible, only God (1 Tim. i, 17): The invisible things of God are understood and discerned by the things that are made (Rom. i, 29). For the things that are discerned, not by sight but by understanding, are incorporeal.
Hereby is destroyed the error of the first natural philosophers, who posited none but material causes. The Gentiles also are refuted, who set up the elements of the world, and the powers therein existing, for gods; also the follies of the Anthropomorphite heretics, who figured God under bodily lineaments; also of the Manicheans, who thought God was an infinite substance of light diffused through infinite space. The occasion of all these errors was that, in thinking of divine things, men came under the influence of the imagination, which can be cognisant only of bodily likeness. And therefore we must transcend imagination in the study of things incorporeal.
1.18 : That in God there is no Composition
1.21 : That God is His own Essence