Plato, Laws 829d

ἔργον καὶ ἐπιφανὲς μηδὲν δράσαντες πώποτε· ὅσοι δὲ ἀγαθοί τε αὐτοὶ καὶ τίμιοι ἐν τῇ πόλει, ἔργων ὄντες δημιουργοὶ καλῶν, τὰ τῶν τοιούτων ᾀδέσθω ποιήματα, ἐὰν καὶ μὴ μουσικὰ πεφύκῃ. κρίσις δὲ αὐτῶν ἔστω παρά τε τῷ παιδευτῇ καὶ τοῖς ἄλλοις νομοφύλαξι, τοῦτο ἀποδιδόντων αὐτοῖς γέρας, παρρησίαν ἐν μούσαις εἶναι μόνοις, τοῖς δὲ ἄλλοις μηδεμίαν ἐξουσίαν γίγνεσθαι, μηδέ τινα τολμᾶν ᾄδειν ἀδόκιμον μοῦσαν μὴ κρινάντων τῶν νομοφυλάκων, μηδʼ ἂν ἡδίων ᾖ τῶν Θαμύρου

or notable deed. But, even though they be not musical, those poems shall be sung which are composed by men who are personally good and honored in the State as performers of noble deeds. The adjudication of these shall lie with the Educator and the rest of the Law-wardens, who shall grant them the sole privilege of free speech in song; whereas to the others no permission shall be given; nor yet shall anyone venture to sing an unauthorized song—