Plato, Laws 817d

τελέως ἡμεῖς τε καὶ ἅπασα ἡ πόλις, ἡτισοῦν ὑμῖν ἐπιτρέποι δρᾶν τὰ νῦν λεγόμενα, πρὶν κρῖναι τὰς ἀρχὰς εἴτε ῥητὰ καὶ ἐπιτήδεια πεποιήκατε λέγειν εἰς τὸ μέσον εἴτε μή. νῦν οὖν, ὦ παῖδες μαλακῶν Μουσῶν ἔκγονοι, ἐπιδείξαντες τοῖς ἄρχουσι πρῶτον τὰς ὑμετέρας παρὰ τὰς ἡμετέρας ᾠδάς, ἂν μὲν τὰ αὐτά γε ἢ καὶ βελτίω τὰ παρʼ ὑμῶν φαίνηται λεγόμενα, δώσομεν ὑμῖν χορόν, εἰ δὲ μή, ὦ φίλοι, οὐκ ἄν ποτε δυναίμεθα.

would be absolutely mad, were it to allow you to do as I have said, before the magistrates had decided whether or not your compositions are deserving of utterance and suited for publication. So now, ye children and offspring of Muses mild, do ye first display your chants side by side with ours before the rulers; and if your utterances seem to be the same as ours or better, then we will grant you a chorus, but if not, my friends, we can never do so.