Summa contra Gentiles3.55 Chapter LV. That the created intellect does not comprehend the divine substance

The mode of any action whatever depends on the efficacity of its active principle,—for that which has the stronger heat imparts greater heat: consequently the mode of knowledge also must depend on the efficiency of the principle of knowledge.

Now the light mentioned above’ is a principle of knowing God: since thereby the created intellect is raised to the vision of the divine substance. Accordingly, the mode of the divine vision must be commensurate with the power of this same light. But this light is far short in strength of the clarity of the divine intelligence. Wherefore it is impossible that the divine substance be seen in the aforesaid light as perfectly as it is seen by the divine intellect. Now the divine intellect sees this substance as perfectly as it is perfectly visible: because the truth of the divine substance, and the clarity of the divine intellect are equal; nay more, they areone. Therefore the created intellect cannot possibly by the aforesaid light see the divine substance as perfectly as it is perfectly visible. Now whoever knows a thing so as to comprehend it, knows it as perfectly as it is knowable: thus whoever knows that a triangle has three angles equal to two right angles, as a matter of opinion based on probable reasons, because wise men say so, does not yet comprehend it; but only he who knows it asa scientific conclusion, through the medium that causes that conclusion. Therefore the created intellect cannot possibly comprehend the divine substance.

Again. A finite power cannot in its operation rise to the level of an infinite object. Now the divine substance is tellect: since every created intellect is confined to a certain species. Therefore the vision of a created intellect cannot possibly rise to the level of the divine substance in seeing it, namely in seeing the divine substance as perfectly as it is visible. Therefore no created intellect comprehends it.

Further. Every agent acts perfectly so far as it perfectly participates in the form that is the principle of action. Now the intelligible form by which the divine substance is seen, is the divine essence itself: and although it becomes the intelligible form of the created intellect, the created intellect does not grasp it as much as it can be grasped. Therefore it does not see it as perfectly as it can be seen. Therefore it is not comprehended by the created intellect.

Besides. Nothing comprehended goes beyond the limits of the comprehender. Consequently if the created intellect were to comprehend the divine substance, this would not exceed the limits of the created intellect: which is impossible. Therefore the created intellect cannot possibly comprehend the divine substance.

We do not however say that the divine substance is seen, yet not comprehended by a created intellect, as though something thereof were seen and something not seen; since the divine substance is utterly simple: but because it is not seen as perfectly by the created intellect as it is visible, even as one who holds a demonstrated conclusion as an opinion is said to know it but not to comprehend it, because he does not know it perfectly, that is scientifically, although there be no part of it that he knows not.