20. But if there is such co-ordination and unity within the holy Triad, who can separate either the Son from the Father, or the Spirit from the Son or from the Father himself? Who would be so audacious as to say that the Triad is unlike itself and diverse in nature, or that the Son is in essence foreign from the Father, or the Spirit alien from the Son? But how are these things? If one should make inquiry and ask again: How, when the Spirit is in us, the Son is said to be in us? How, when the Son is in us, the Father is said to be in us? Or how, when it is truly a Triad, the Triad is described as one? Or why, when the One is in us, the Triad is said to be in us?—let him first divide the radiance from the light, or wisdom from the wise, or let him tell how these things are. But if this is not to be done, much more is it the audacity of madmen to make such inquiries concerning God. For tradition, as we have said, does not declare the Godhead to us by demonstration in words, but by faith and by a pious and reverent use of reason. For if Paul proclaimed the saving Gospel of the Cross, ‘not in words of wisdom, but in demonstration of the Spirit and of power’; and if in Paradise he heard ‘unspeakable words which it is not lawful for a man to utter’: who can declare the holy Triad itself? Nevertheless, we can meet this difficulty, primarily by faith and then by using the illustrations mentioned above, I mean the image and the radiance, fountain and river, essence and expression. As the Son is in the Spirit as in his own image, so also the Father is in the Son. For divine Scripture, by way of relieving the impossibility of explaining and apprehending these matters in words, has given us illustrations of this kind; that it may be lawful, because of the unbelief of presumptuous men, to speak more plainly, and to speak without danger, and to think legitimately, and to believe that there is one sanctification, which is derived from the Father, through the Son, in the Holy Spirit.

As the Son is an only-begotten offspring, so also the Spirit, being given and sent from the Son, is himself one and not many, nor one from among many, but Only Spirit. As the Son, the living Word, is one, so must the vital activity and gift whereby he sanctifies and enlightens be one perfect and complete; which is said to proceed from the Father,* because it is from the Word, who is confessed to be from the Father, that it shines forth and is sent and is given. The Son is sent from the Father; for he says, ‘God so loved the world that he gave his only begotten Son.’ The Son sends the Spirit; ‘If I go away,’ he says, ‘I will send the Paraclete.’ The Son glorifies the Father, saying: ‘Father, I have glorified thee.’ The Spirit glorifies the Son; for he says: ‘He shall glorify me.’ The Son says: ‘The things I heard from the Father speak I unto the world.’ The Spirit takes of the Son; ‘He shall take of mine,’ he says, ‘and shall declare it unto you.’ The Son came in the name of the Father. ‘The Holy Spirit,’ says the Son, ‘whom the Father will send in my name.’

Τοιαύτης δὲ συστοιχίας καὶ ἑνότητος τῆς ἐν τῇ ἁγίᾳ Τριάδι οὔσης, τίς ἂν διέλοι ἢ τὸν Υἱὸν ἀπὸ τοῦ Πατρὸς, ἢ τὸ Πνεῦμα ἀπὸ τοῦ Υἱοῦ, ἢ αὐ τοῦ τοῦ Πατρός; ἢ τίς οὕτω τολμηρὸς, ὡς εἰπεῖν ἀνόμοιον καὶ ἑτεροφυῆ τὴν Τριάδα πρὸς ἑαυτὴν, ἢ ἀλλοτριοούσιον τοῦ Πατρὸς τὸν Υἱὸν, ἢ ξένον τὸ Πνεῦμα τοῦ Υἱοῦ; Πῶς δὲ ταῦτά ἐστιν; ἄν τις πά λιν ἐρωτήσειε ζητῶν· πῶς τοῦ Πνεύματος ὄντος ἐν ἡμῖν, λέγεται ὁ Υἱὸς εἶναι ἐν ἡμῖν, τοῦ τε Υἱοῦ ὄντος ἐν ἡμῖν, λέγεται ὁ Πατὴρ εἶναι ἐν ἡμῖν; ἢ πῶς ὅλως Τριάδος οὔσης, ἐν ἑνὶ σημαίνεται ἡ Τριάς; ἢ πῶς τοῦ ἑνὸς ὄντος ἐν ἡμῖν, ἡ Τριὰς ἐν ἡμῖν λέγεται; διελέτω πρῶτον αὐτὸς τὸ ἀπαύγασμα τοῦ φωτὸς, ἢ τὴν σοφίαν τοῦ σοφοῦ· ἢ εἰπάτω, πῶς ἐστι ταῦτα. Εἰ δὲ μὴ τοῦτο δύναται, πολλῷ πλέον περὶ Θεοῦ τοιαῦτα ζητεῖν μαινομένων ἐστὶ τὸ τόλμημα· ἡ γὰρ θεότης οὐκ ἐν ἀποδείξει λόγων, ὥσπερ εἴρη ται, παραδίδοται, ἀλλ' ἐν πίστει καὶ εὐσεβεῖ λογισμῷ μετ' εὐλαβείας. Εἰ γὰρ καὶ τὰ περὶ τοῦ σωτηριώδους σταυροῦ, «οὐκ ἐν σοφίᾳ λόγων, ἀλλ' ἐν ἀποδείξει πνεύματος καὶ δυνάμεως,» ἐκήρυττεν ὁ Παῦλος, «καὶ ἀῤῥήτων δὲ ῥημάτων ἤκουσεν» ἐν τῷ παραδείσῳ, «ἃ μὴ ἐξὸν ἀνθρώπῳ λαλῆσαι·» περὶ αὐτῆς τῆς ἁγίας Τριάδος τίς ἐξειπεῖν δύναται; Ὅμως δ' οὖν τὴν τοιαύτην ἀπορίαν δυνήσεταί τις θεραπεύειν προηγουμένως μὲν τῇ πίστει, ἔπειτα δὲ καὶ ἐκ τῶν προειρημένων, φημὶ δὴ, τῆς εἰκόνος καὶ τοῦ ἀπαυγάσματος, καὶ πηγῆς, καὶ ποταμοῦ, καὶ ὑποστάσεως, καὶ χαρακτῆρος. Ὥσπερ γὰρ ἐν ἰδίᾳ εἰ κόνι ἐστὶν ὁ Υἱὸς ἐν τῷ Πνεύματι, οὕτω καὶ ὁ Πατὴρ ἐν τῷ Υἱῷ. Καὶ γὰρ τὸ ἀδύνατον τῆς διὰ λόγων ἑρμηνείας, καὶ τοῦ καταλαβεῖν τὰ τοιαῦτα παραμυθουμένη ἡ θεία Γραφὴ, τοιαῦτα καὶ τὰ παραδείγματα δέδωκεν ἡμῖν, ἵν' οὕτω διὰ τὴν ἀπιστίαν τῶν τολμηρῶν λέγειν ἁπλούστερον, καὶ λέγειν ἀκινδύνως, καὶ μετὰ συγγνώμης νοεῖν ἐξῇ, καὶ πιστεύειν ἕνα εἶναι τὸν ἁγιασμὸν, τὸν ἐκ Πατρὸς δι' Υἱοῦ ἐν Πνεύματι ἁγίῳ γινόμενον. Καὶ γὰρ ὥσπερ μονογενὴς ὁ Υἱός ἐστιν· οὕτω καὶ τὸ Πνεῦμα παρὰ τοῦ Υἱοῦ διδόμενον καὶ πεμπόμενον, καὶ αὐτὸ ἕν ἐστι καὶ οὐ πολλὰ, οὐδὲ ἐκ πολλῶν ἓν, ἀλλὰ μόνον αὐτὸ Πνεῦμα. Ἑνὸς γὰρ ὄντος τοῦ Υἱοῦ, τοῦ ζῶντος Λόγου, μίαν εἶναι δεῖ τελείαν καὶ πλήρη τὴν ἁγιαστικὴν καὶ φωτιστικὴν ζῶσαν ἐνέργειαν αὐ τοῦ καὶ δωρεὰν, ἥτις ἐκ Πατρὸς λέγεται ἐκπορεύεσθαι, ἐπειδὴ παρὰ τοῦ Λόγου τοῦ ἐκ Πατρὸς ὁμολογουμένου ἐκλάμπει, καὶ ἀποστέλλεται, καὶ δίδοται. Ἀμέλει ὁ μὲν Υἱὸς παρὰ τοῦ Πατρὸς ἀποστέλλεται· «Οὕτω» γὰρ, φησὶν, «ὁ Θεὸς ἠγάπησε τὸν κόσμον, ὥστε τὸν Υἱὸν αὐτοῦ τὸν μονογενῆ ἀπέστειλεν.» Ὁ δὲ Υἱὸς τὸ Πνεῦμα ἀποστέλλει· «Ἐὰν» γὰρ, φησὶν, «ἐγὼ ἀπέλθω, ἀποστελῶ τὸν Παράκλητον.» Καὶ ὁ μὲν Υἱὸς τὸν Πατέρα δοξάζει, λέγων· «Πάτερ, ἐγώ σε ἐδόξασα·» τὸ δὲ Πνεῦμα δοξάζει τὸν Υἱόν· «Ἐκεῖ νος» γὰρ, φησὶν, «ἐμὲ δοξάσει.» Καὶ ὁ μὲν Υἱός φησιν· «Ἃ ἤκουσα παρὰ τοῦ Πατρὸς, ταῦτα καὶ λαλῶ εἰς τὸν κόσμον·» τὸ δὲ Πνεῦμα ἐκ τοῦ Υἱοῦ λαμβάνει· «Ἐκ τοῦ ἐμοῦ» γὰρ «λήψεται καὶ ἀναγγελεῖ ὑμῖν,» φησί. Καὶ ὁ μὲν Υἱὸς ἐν τῷ ὀνόματι τοῦ Πατρὸς ἦλθε· «Τὸ δὲ Πνεῦμα τὸ ἅγιον,» φησὶν ὁ Υἱὸς, «ὃ πέμψει ὁ Πατὴρ ἐν τῷ ὀνόματί μου.»