Plato, Laws 664d

γίγνεσθαι ἐπευχόμενος. δεῖ δὲ δὴ καὶ ἔτι τρίτους τοὺς ὑπὲρ τριάκοντα ἔτη μέχρι τῶν ἑξήκοντα γεγονότας ᾄδειν· τοὺς δὲ μετὰ ταῦτα—οὐ γὰρ ἔτι δυνατοὶ φέρειν ᾠδάς—μυθολόγους περὶ τῶν αὐτῶν ἠθῶν διὰ θείας φήμης καταλελεῖφθαι. λέγεις δέ, ὦ ξένε, τίνας τούτους τοὺς χοροὺς τοὺς τρίτους; οὐ γὰρ πάνυ συνίεμεν σαφῶς ὅτι ποτὲ βούλει φράζειν αὐτῶν πέρι. καὶ μὴν εἰσίν γε οὗτοι σχεδὸν ὧν χάριν οἱ πλεῖστοι τῶν ἔμπροσθεν ἐρρήθησαν λόγων.

The next singers will be the third choir, of those over thirty and under sixty; and lastly, there were left those who, being no longer able to uplift the song, shall handle the same moral themes in stories and by oracular speech. Whom do you mean, Stranger, by these third choristers. For we do not grasp very clearly what you intend to convey about them. Yet they are in fact the very people to whom most of our previous discourse was intended to lead up.