Nicene and Post-Nicene Fathers, Vol. II:
City of God: Chapter 29

Chapter 29.—Of the Knowledge by Which the Holy Angels Know God in His Essence, and by Which They See the Causes of His Works in the Art of the Worker, Before They See Them in the Works of the Artist.

Those holy angels come to the knowledge of God not by audible words, but by the presence to their souls of immutable truth, i.e., of the only-begotten Word of God; and they know this Word Himself, and the Father, and their Holy Spirit, and that this Trinity is indivisible, and that the three persons of it are one substance, and that there are not three Gods but one God; and this they so know that it is better understood by them than we are by ourselves.  Thus, too, they know the creature also, not in itself, but by this better way, in the wisdom of God, as if in the art by which it was created; and, consequently, they know themselves better in God than in themselves, though they have also this latter knowledge.  For they were created, and are different from their Creator.  In Him, therefore, they have, as it were, a noonday knowledge; in themselves, a twilight knowledge, according to our former explanations. 500   For there is a great difference between knowing a thing in the design in conformity to which it was made, and knowing it in itself,—e.g., the straightness of lines and correctness of figures is known in one way when mentally conceived, in another when described on paper; and justice is known in one way in the unchangeable truth, in another in the spirit of a just man.  So is it with all other things,—as, the firmament between the water above and below, which was called the heaven; the gathering of the waters beneath, and the laying bare of the dry land, and the production of plants and trees; the creation of sun, moon, and stars; and of the animals out of the waters, fowls, and fish, and monsters of the deep; and of everything that walks or creeps on the earth, and of man himself, who excels all that is on the earth,—all these things are known in one way by the angels in the Word of God, in which they see the eternally abiding causes and reasons according to which they were made, and in another way in themselves:  in the former, with a clearer knowledge; in the latter, with a knowledge dimmer, and rather of the bare works than of the design.  Yet, when these works are referred to the praise and adoration of the Creator Himself, it is as if morning dawned in the minds of those who contemplate them.

Footnotes

Ch. 7.