Plato, Meno 94b

Περικλέα, οὕτως μεγαλοπρεπῶς σοφὸν ἄνδρα, οἶσθʼ ὅτι δύο ὑεῖς ἔθρεψε, Πάραλον καὶ Ξάνθιππον; ἔγωγε. τούτους μέντοι, ὡς οἶσθα καὶ σύ, ἱππέας μὲν ἐδίδαξεν οὐδενὸς χείρους Ἀθηναίων, καὶ μουσικὴν καὶ ἀγωνίαν καὶ τἆλλα ἐπαίδευσεν ὅσα τέχνης ἔχεται οὐδενὸς χείρους· ἀγαθοὺς δὲ ἄρα ἄνδρας οὐκ ἐβούλετο ποιῆσαι; δοκῶ μέν, ἐβούλετο, ἀλλὰ μὴ οὐκ ᾖ διδακτόν. ἵνα δὲ μὴ ὀλίγους οἴῃ καὶ τοὺς φαυλοτάτους Ἀθηναίων ἀδυνάτους γεγονέναι τοῦτο

the splendidly accomplished Pericles: he, as you are aware, brought up two sons, Paralus and Xanthippus. Yes. And, you know as well as I, he taught them to be the foremost horsemen of Athens, and trained them to excel in music and gymnastics and all else that comes under the head of the arts; and with all that, had he no desire to make them good men? He wished to, I imagine, but presumably it is not a thing one can be taught. And that you may not suppose it was only a few of the meanest sort of Athenians who failed in this matter,