The eighth book very notably overthrows the blasphemy of the hereticswho say that the Only-begotten came from nothing, and that there was a time when He was not, and shows the Son to be no new being, but from everlasting, from His having said to Moses, I am He that is, and to Manoah, Why ask thou My name? It also is wonderful —moreover David also says to God, You are the same, and Your years shall not fail; and furthermore Isaiah says, I am God, the first, and hereafter am I: and the Evangelist, He was in the beginning, and was with God, and was God: — and that He has neither beginning nor end: — and he proves that those who say that He is new and comes from nothing are idolaters. And herein he very finely interprets the brightness of the glory, and the express image of the Person
These, then, are the strong points of Eunomius' case; and I think that when those which promised to be powerful are proved by argument to be so rotten and unsubstantial, I may well keep silence concerning the rest, since the others are practically refuted, concurrently with the refutation of the stronger ones; just as it happens in warlike operations that when a force more powerful than the rest has been beaten, the remainder of the army are no longer of any account in the eyes of those by whom the strong portion of it has been overcome.
But the fact that the chief part of his blasphemy lies in the later part of his discourse forbids me to be silent. For the transition of the Only-begotten from nothing into being, that horrid and godless doctrine of Eunomius, which is more to be shunned than all impiety, is next maintained in the order of his argument. And since every one who has been bewitched by this deceit has the phrase, “If He was, He has not been begotten, and if He has been begotten, He was not,” ready upon his tongue for the maintenance of the doctrine that He Who made of nothing us and all the creation is Himself from nothing, and since the deceit obtains much support thereby, as men of feebler mind are pressed by this superficial bit of plausibility, and led to acquiesce in the blasphemy, we must needs not pass by this doctrinal “root of bitterness,” lest, as the Apostle says, it “spring up and trouble us.”
Now I say that we must first of all consider the actual argument itself, apart from our contest with our opponents, and thus afterwards proceed to the examination and refutation of what they have set forth.
Source: Against Eunomius (New Advent)