Against Praxeas

He existed before the creation of the world, up to the generation of the Son. For before all things God was alone--being in Himself and for Himself universe, and space, and all things. Moreover, He was alone, because there was nothing external to Him but Himself. Yet even not then was He alone; for He had with Him that which He possessed in Himself, that is to say, His own Reason. For God is rational, and Reason was first in Him; and so all things were from Himself.