16. We ought therefore, as I said before, to be silent on these matters and to disregard these people. But lest our silence should furnish an excuse for their effrontery, let them listen. Just as we cannot ascribe a father to the Father, so neither can we ascribe a brother to the Son. Other than the Father, as we have written already, there is no God; there is no other Son than the Son, for he is only begotten. Hence the Father, being One and Only, is Father of a Son who is One and Only; and in the Godhead alone the term ‘Father’ and the term ‘Son’ keep to their meaning and are ever thus. For with men, if a man is called a father, he is, notwithstanding, another man’s son; and if he is called a son, he is, notwithstanding, another man’s father. So that with men the names ‘father’ and ‘son’ are not kept to their strict meaning. Abraham, for example, being Nahor’s son, is Isaac’s father; and Isaac, being Abraham’s son, is Jacob’s father. And so it is by the nature of men. For they are parts of one another; and each, when he is begotten, receives a part of his father, that he may himself become father of another. But with the Godhead it is not so. For God is not as man, nor is his nature divided. Hence he does not, by division of himself, beget a son, so that he may himself become father to another; for he himself is not from a father. Nor is the Son a part of the Father. Hence he does not beget as he himself has been begotten, but is whole image and radiance of the whole. And in the Godhead alone, the Father is a father in the strict sense, and the Son a son in the strict sense; and of these it holds good that the Father is ever Father and the Son ever Son. As the Father could never be son, so neither could the Son be a father. As the Father will never cease to be Only Father, so the Son will never cease to be Only Son. By all accounts then, it is madness to envisage a brother to the Son, or to ascribe to the Father the name of grandfather. For the Spirit is not given the name of son in the Scriptures, lest he be taken for a brother; nor son of the Son, lest the Father be thought to be a grandfather. But the Son is called Son of the Father, and the Spirit of the Father is called Spirit of the Son. Thus the Godhead of the Holy Triad and faith therein is one.

Σιωπᾷν μὲν οὖν, ὡς προεῖπον, ἐπὶ τούτοις, καὶ μὴ προσποιεῖσθαι τοὺς τοιούτους ἔδει· ἵνα δὲ μὴ ἡ ἡμῶν σιωπὴ πρόφασιν ἀναισχυντίας αὐτοῖς ἐμποιήσῃ, ἀκουέτωσαν· Ὥσπερ οὐκ ἔστιν ἐπὶ τοῦ Πατρὸς εἰπεῖν πατέρα, οὕτως οὐκ ἔστιν ἐπὶ τοῦ Υἱοῦ εἰπεῖν ἀδελφόν. Τοῦ μὲν γὰρ Πατρὸς, ὡς γέ γραπται ἔμπροσθεν, ἄλλος Θεὸς οὐ γέγονεν· Υἱὸς δὲ οὐκ ἔστιν ἄλλος· μονογενὴς γάρ ἐστι· διὸ καὶ μόνος καὶ εἷς ὁ Πατὴρ, μόνου καὶ ἑνὸς Υἱοῦ Πα τήρ ἐστι· καὶ ἐπὶ μόνης τῆς θεότητος τὸ Πατὴρ καὶ τὸ Υἱὸς ἕστηκεν ἀεὶ καὶ ἔστι. Τῶν μὲν γὰρ ἀνθρώπων εἰ πατὴρ λέγεταί τις, ἀλλ' ἑτέρου γέγονεν υἱός· καὶ εἰ υἱὸς λέγεται, ἀλλ' ἑτέρου γέγονε πα τήρ· ὥστε ἐπ' ἀνθρώπων μὴ σώζεσθαι κυρίως τὸ πατρὸς καὶ υἱοῦ ὄνομα. Ἀβραὰμ γοῦν, υἱὸς ὢν τοῦ Θάῤῥου, πατὴρ γέγονε τοῦ Ἰσαάκ· καὶ Ἰσαὰκ, υἱὸς ὢν τοῦ Ἀβραὰμ, πατὴρ γέγονε τοῦ Ἰακώβ· καὶ τοῦτον τὸν τρόπον ἡ φύσις τῶν ἀνθρώπων ἔχει· μέρη γάρ εἰσιν ἀλλήλων· καὶ ἕκαστος γεννώμενος ἔχει τοῦ πατρὸς μέρος, ἵνα καὶ αὐτὸς ἑτέρου γένη ται πατήρ. Ἐπὶ δὲ τῆς θεότητος οὐκ ἔστιν οὕτως. Οὐ γὰρ ὡς ἄνθρωπος ὁ Θεὸς, οὐδὲ μεριζομένην ἔχει φύσιν· διὸ οὐδὲ γεννᾷ Υἱὸν μεριζόμενος, ἵνα καὶ αὐτὸς γένηται Πατὴρ ἑτέρου, ἐπεὶ μηδ' αὐτός ἐστιν ἐκ Πατρός· οὔτε ὁ Υἱὸς δὲ μέρος ἐστὶ τοῦ Πα τρός· διὸ καὶ οὐδὲ γεννᾷ, ὥσπερ γεγέννηται αὐτὸς, ἀλλὰ ὅλος ἐστὶν ὅλου εἰκὼν καὶ ἀπαύγασμα· καὶ ἐπὶ τῆς θεότητος μόνης ὁ Πατὴρ κυρίως ἐστὶ Πατήρ· καὶ ὁ Υἱὸς, κυρίως Υἱός ἐστιν· καὶ ἐπὶ τούτων ἕστηκε τὸ Πατὴρ ἀεὶ Πατὴρ, καὶ τὸ Υἱὸς ἀεὶ Υἱός. Καὶ ὥσπερ οὐκ ἂν εἴη ποτὲ ὁ Πατὴρ Υἱὸς, οὕτως οὐκ ἄν ποτε γένοιτο ὁ Υἱὸς Πατήρ. Καὶ ὥσπερ οὐ παύσεταί ποτε ὁ Πατὴρ μόνος ὢν Πατὴρ, οὕτως οὐ παύσεταί ποτε ὁ Υἱὸς μόνος ὢν Υἱός. Μανία ἄρα κἂν ὅλως ἐνθυμεῖσθαι καὶ λέγειν ἐπὶ μὲν Υἱοῦ ἀδελφὸν, ἐπὶ δὲ Πατρὸς τὸ πάππου ὄνομα. Οὐδὲ γὰρ ὠνομάσθη ἐν ταῖς Γραφαῖς υἱὸς τὸ Πνεῦμα, ἵνα μὴ ἀδελφὸς νομισθῇ· οὐδὲ υἱὸς τοῦ Υἱοῦ, ἵνα μὴ πάπ πος νοοῖτο ὁ Πατήρ· ἀλλ' ὁ Υἱὸς, τοῦ Πατρὸς υἱὸς, καὶ τὸ Πνεῦμα τοῦ Πατρὸς πνεῦμα εἴρηται· καὶ οὕτως τῆς ἁγίας Τριάδος μία ἡ θεότης καὶ πίστις ἐστίν.