God’s Essence the Only Species in His Understanding

The foregoing exposition makes it clear that God understands through no other species than through His essence.

The reason is, that any intellect which understands through a species other than itself, is related to that intelligible species as potency to act. For an intelligible species is a perfection of the intellect, causing 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.

In consequence of this, 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 man is properly known through the definition of man, and horse is known through the definition of 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.

Reference

St. Thomas Aquinas. (1265-1274). Compendium Theologiae: God’s Essence the Only Species in His Understanding, trans. by Cyril Vollert. St. Louis & London: B. Herder Book Co., 1947

All scripture is given by inspiration of God and is profitable for doctrine, reproof, correction, and instruction in righteousness (2 Timothy 3:16).

Agere Sequitur Esse