Plato, Laws 647d

νικῶντα αὐτὴν δεῖ τέλεον οὕτω γίγνεσθαι πρὸς ἀνδρείαν, ἄπειρος δὲ δήπου καὶ ἀγύμναστος ὢν τῶν τοιούτων ἀγώνων ὁστισοῦν οὐδʼ ἂν ἥμισυς ἑαυτοῦ γένοιτο πρὸς ἀρετήν, σώφρων δὲ ἄρα τελέως ἔσται μὴ πολλαῖς ἡδοναῖς καὶ ἐπιθυμίαις προτρεπούσαις ἀναισχυντεῖν καὶ ἀδικεῖν διαμεμαχημένος καὶ νενικηκὼς μετὰ λόγου καὶ ἔργου καὶ τέχνης ἔν τε παιδιαῖς καὶ ἐν σπουδαῖς, ἀλλʼ ἀπαθὴς ὢν πάντων τῶν τοιούτων; οὔκουν τόν γʼ εἰκότα λόγον ἂν ἔχοι.

that a man can become perfect, and no one unversed and unpracticed in contests of this sort can attain even half the excellence of which he is capable,—in the case of temperance, on the other hand, a man may attain perfection without a stubborn fight against hordes of pleasures and lusts which entice towards shamelessness and wrong-doing, and without conquering them by the aid of speech and act and skill, alike in play and at work,—and, in fact, without undergoing any of these experiences? It would not be reasonable to suppose so.