Letter 863: Virtue must be practiced with all one's strength — not merely admired from a distance.

To Theon. Not the power of the preaching alone, my admirable friend, but also the life of the preachers, when it accorded with the preaching, drew people in. For who would have been persuaded by men who say one thing but do another? For if even now many who have been rooted in the faith have, on account of the life of their instructors, not only been shaken but even torn up by the very roots, who at the beginning—not seeing a manner of life that accorded with what was being said—would have been persuaded? And this, when he was being commanded to stand apart from his ancestral gods and customs, and to hate wealth and luxury and pleasure, but to embrace poverty and fasting and chastity, and to prepare himself for deaths that came day by day.

Οὐχ ἡ δύναμις μόνον, ὦ θαυμάσιε, τοῦ κηρύγμα-τος, ἀλλὰ καὶ ὁ βίος τῶν κηρυττόντων συμβαίνων τῷ κηρύγματι, τοὺς ἀνθρώπους ἐπηγάγετο. Τὶς γὰρ ἂν ἐπείσθη ἀνθρώπους, ἀλλὰ μὲν φράζουσιν, ἕτερα δὲ πράττουσιν; Εἰ γὰρ νῦν πολλοὶ ῥιζωθέντες ἐν τῇ πίστει, ἐκ τοῦ βίου τῶν ὑφηγητῶν, οὐ μόνον ἐσαλεύ-θησαν, ἀλλὰ καὶ αὐτόπρεμνοι ἀνεσπάσθησαν· τίς ἂν παρὰ τὴν ἀρχὴν μὴ ὁρῶν πολιτείαν τοῖς λεγομέ-νοις συμβαίνουσαν ἐπείσθη; καὶ ταῦτα, κελευόμενος τῶν πατρῴων θεῶν τε καὶ ἐθῶν ἀποστῆναι, καὶ πλοῦ-τον καὶ τρυφὴν καὶ ἡδονὴν μισῆσαι, ἀσπάσασθαι δὲ ἀκτημοσύνην καὶ νηστείαν, καὶ ἁγνείαν, καὶ πρὸς καθημερινοὺς παρασκευάσασθαι θανάτους.