In truth, the question you propound to us is no small one, nor such that but small harm will follow if it meets with insufficient treatment. For by the force of the question, we are at first sight compelled to accept one or other of two erroneous opinions, and either to say “there are three Gods,” which is unlawful, or not to acknowledge the Godhead of the Son and the Holy Spirit, which is impious and absurd.

Ἔστι δὲ οὐ μικρὸς οὗτος ὁ λόγος ὃν προέτεινας ἡμῖν οὐδὲ τοιοῦτος ὡς ὀλίγην φέρειν ζημίαν, εἰ μὴ τῆς προσηκούσης ἐξετάσεως τύχοι. ἀνάγκη γὰρ ἐκ τῆς βίας τοῦ ἐρωτήματος ἑνὶ πάντως τῶν ἀπεμφαινόντων συνενεχθῆναι κατὰ τὸν πρόχειρον νοῦν καὶ ἢ τρεῖς λέγειν θεούς, ὅπερ ἀθέμιτον, ἢ μὴ προσμαρτυρεῖν τῷ υἱῷ καὶ τῷ πνεύματι τὴν θεότητα, ὅπερ ἀσεβές τε καὶ ἄτοπον. τὸ δὲ λεγόμενον παρὰ σοῦ τοιοῦτόν ἐστιν: Πέτρος καὶ Ἰάκωβος καὶ Ἰωάννης, ἐν μιᾷ ὄντες τῇ ἀνθρωπότητι, τρεῖς ἄνθρωποι λέγονται: καὶ οὐδὲν ἄτοπον τοὺς συνημμένους κατὰ τὴν φύσιν, εἰ πλείους εἶεν, ἐκ τοῦ τῆς φύσεως ὀνόματος πληθυντικῶς ἀριθμεῖσθαι. εἰ οὖν ἐκεῖ τοῦτο δίδωσιν ἡ συνήθεια καὶ ὁ ἀπαγορεύων οὐκ ἔστι δύο λέγειν τοὺς δύο καὶ τρεῖς τοὺς ὑπὲρ δύο, πῶς, ἐπὶ τῶν μυστικῶν δογμάτων τὰς τρεῖς ὑποστάσεις ὁμολογοῦντες καὶ οὐδεμίαν ἐπ' αὐτῶν τὴν κατὰ φύσιν διαφορὰν ἐννοοῦντες, μαχόμεθα τρόπον τινὰ τῇ ὁμολογίᾳ, μίαν μὲν τὴν θεότητα τοῦ πατρὸς καὶ τοῦ υἱοῦ καὶ τοῦ ἁγίου πνεύματος λέγοντες, τρεῖς δὲ θεοὺς λέγειν ἀπαγορεύοντες;