Accordingly the everlasting God generates His own Word which is perfect, without beginning and without end, that God, Whose nature and existence are above time, may not engender in time. But with man clearly it is otherwise, for generation is with him a matter of sex, and destruction and flux and increase and body clothe him round about , and he possesses a nature which is male or female. For the male requires the assistance of the female. But may He Who surpasses all, and transcends all thought and comprehension, be gracious to us.

The holy catholic and apostolic Church, then, teaches the existence at once of a Father: and of His Only-begotten Son, born of Him without time and flux and passion, in a manner incomprehensible and perceived by the God of the universe alone: just as we recognise the existence at once of fire and the light which proceeds from it: for there is not first fire and thereafter light, but they exist together. And just as light is ever the product of fire, and ever is in it and at no time is separate from it, so in like manner also the Son is begotten of the Father and is never in any way separate from Him, but ever is in Him . But whereas the light which is produced from fire without separation, and abides ever in it, has no proper subsistence of its own distinct from that of fire (for it is a natural quality of fire), the Only-begotten Son of God, begotten of the Father without separation and difference and ever abiding in Him, has a proper subsistence of its own distinct from that of the Father. — Book I, Chapter 8, Concerning the Holy Trinity.