For the Son was certainly not Unbegotten for ages infinite and without beginning within the Father, as one thing within another that differs from itself, being a part of Him which afterwards was changed and cast out from Him; for such a being would be subject to change; and there would also be according to this two Unbegotten Beings, He that cast forth and He that was cast forth. And which condition would be the better? Would not that before the change which caused a division by the (b) sending forth? It is, then, impossible to conceive of the Son coming from the Father as a part or a limb that had always previously been united to Him, afterwards separating and coming apart from the whole. For these are unspeakable and quite impious ideas, proper enough to the relations of material bodies, but foreign to a nature without body or matter. And, therefore, here again we had best say: Who shall declare His generation?