Plato, Laws 791d

τίνα οὖν ἂν τρόπον εὐθὺς ἐμφύοιθʼ ἡμῖν ὁπότερον βουληθεῖμεν τῷ νεογενεῖ, φράζειν δὴ πειρατέον ὅπως τις καὶ καθʼ ὅσον εὐπορεῖ τούτων. πῶς γὰρ οὔ; λέγω δὴ τό γε παρʼ ἡμῖν δόγμα, ὡς ἡ μὲν τρυφὴ δύσκολα καὶ ἀκράχολα καὶ σφόδρα ἀπὸ σμικρῶν κινούμενα τὰ τῶν νέων ἤθη ἀπεργάζεται, τὸ δὲ τούτων ἐναντίον, ἥ τε σφοδρὰ καὶ ἀγρία δούλωσις, ταπεινοὺς καὶ ἀνελευθέρους καὶ μισανθρώπους ποιοῦσα, ἀνεπιτηδείους συνοίκους ἀποτελεῖ.

What way can we find, then, for implanting at once in the new-born child whichever of these qualities we desire? We must endeavor to indicate how and to what extent we have them at our command. By all means. The doctrine held amongst us, I may explain, is this,—that whereas luxurious living renders the disposition of the young morose and irascible and too easily moved by trifles, its opposite (which is uttermost and cruel enslavement) makes them lowly and mean-spirited and misanthropic, and thus unfit to associate with others.