4. On this account and reasonably, having said before, ‘I and the Father are One,’ He added, ‘I in the Father and the Father in Me,’ by way of shewing the identity of Godhead and the unity of Essence. For they are one, not as one thing divided into two parts, and these nothing but one, nor as one thing twice named, so that the Same becomes at one time Father, at another His own Son, for this Sabellius holding was judged an heretic. But They are two, because the Father is Father and is not also Son, and the Son is Son and not also Father; but the nature is one; (for the offspring is not unlike its parent, for it is his image), and all that is the Father’s, is the Son’s. Wherefore neither is the Son another God, for He was not procured from without, else were there many, if a godhead be procured foreign from the Father’s; for if the Son be other, as an Offspring, still He is the Same as God; and He and the Father are one in propriety and peculiarity of nature, and in the identity of the one Godhead, as has been said. For the radiance also is light, not second to the sun, nor a different light, nor from participation of it, but a whole and proper offspring of it. And such an offspring is necessarily one light; and no one would say that they are two lights, but sun and radiance two, yet one the light from the sun enlightening in its radiance all things. So also the Godhead of the Son is the Father’s; whence also it is indivisible; and thus there is one God and none other but He. And so, since they are one, and the Godhead itself one, the same things are said of the Son, which are said of the Father, except His being said to be Father:—for instance, that He is God, ‘And the Word was God;’ Almighty, ‘Thus saith He which was and is and is to come, the Almighty;’ Lord, ‘One Lord Jesus Christ;’ that He is Light, ‘I am the Light;’ that He wipes out sins, ‘that ye may know,’ He says, ‘that the Son of man hath power upon earth to forgive sins;’ and so with other attributes. For ‘all things,’ says the Son Himself, ‘whatsoever the Father hath, are Mine;’ and again, ‘And Mine are Thine.’