Chapter 30 — That God understands through no other species than his own essence

The foregoing exposition makes it clear that God understands through no other species than through his essence. For any intellect that understands through a species other than itself is related to that intelligible species as potency to act, since an intelligible species is a perfection of the intellect that causes it to understand in act. Therefore, if nothing in God is in potency, but he is pure act, he must understand through his own essence, and not through any other kind of species. From this it follows that he directly and principally understands himself. For the essence of a thing does not properly and directly lead to the knowledge of anything else than of that being whose essence it is. Thus what is properly known through the definition of man is man, and what is properly known through the definition of horse is horse. Therefore, if God understands through his essence, that which is directly and principally understood by him must be God himself. And, since God is his own essence, it follows that, in him, understanding and that whereby he understands and that which is understood are absolutely identical.