Plato, Laws 797c

τι νέον ἀεὶ καινοτομοῦντα καὶ εἰσφέροντα τῶν εἰωθότων ἕτερον κατά τε σχήματα καὶ χρώματα καὶ πάντα ὅσα τοιαῦτα, τοῦτον τιμᾶσθαι διαφερόντως, τούτου πόλει λώβην οὐκ εἶναι μείζω φαῖμεν ἂν ὀρθότατα λέγοντες· λανθάνειν γὰρ τῶν νέων τὰ ἤθη μεθιστάντα καὶ ποιεῖν τὸ μὲν ἀρχαῖον παρʼ αὐτοῖς ἄτιμον, τὸ δὲ νέον ἔντιμον. τούτου δὲ πάλιν αὖ λέγω τοῦ τε ῥήματος καὶ τοῦ δόγματος οὐκ εἶναι ζημίαν μείζω πάσαις πόλεσιν· ἀκούσατε δὲ ὅσον φημὶ αὔτʼ εἶναι κακόν.

in the matter of form or color or something of the sort; whereas it would be perfectly true to say that a State can have no worse pest than a man of that description, since he privily alters the characters of the young, and causes them to contemn what is old and esteem what is new. And I repeat again that there is no greater mischief a State can suffer than such a dictum and doctrine: just listen while I tell you how great an evil it is.