Plato, Laws 788c

ὥστε ἀπορία μὲν περὶ αὐτὰ νομοθετεῖν, σιγᾶν δὲ ἀδύνατον. ἃ δὲ λέγω, δηλῶσαι πειρατέον οἷον δείγματα ἐξενεγκόντα εἰς φῶς· νῦν γὰρ λεγομένοις ἔοικε κατά τι σκότος. ἀληθέστατα λέγεις. οὐκοῦν ὅτι μὲν σώματα καὶ ψυχὰς τήν γε ὀρθὴν πάντως δεῖ τροφὴν φαίνεσθαι δυναμένην ὡς κάλλιστα καὶ ἄριστα ἐξεργάζεσθαι, τοῦτο μὲν ὀρθῶς εἴρηταί που. τί μήν;

Hence, while it is impossible to pass over these practices in silence, it is difficult to legislate concerning them. The practices I refer to I will try to make clear by bringing some specimens, as it were, to the light; for at present my words rather resemble a dark speech. That is quite true. When we said that right nurture must be manifestly capable of making both bodies and souls in all respects as beautiful and good as possible, we spoke, I presume, truly? Certainly we did.