Plato, Laws 664a

πείσειν ὅτι ἂν ἐπιχειρῇ τις πείθειν τὰς τῶν νέων ψυχάς, ὥστε οὐδὲν ἄλλο αὐτὸν δεῖ σκοποῦντα ἀνευρίσκειν ἢ τί πείσας μέγιστον ἀγαθὸν ἐργάσαιτο ἂν πόλιν, τούτου δὲ πέρι πᾶσαν μηχανὴν εὑρίσκειν ὅντινά ποτε τρόπον ἡ τοιαύτη συνοικία πᾶσα περὶ τούτων ἓν καὶ ταὐτὸν ὅτι μάλιστα φθέγγοιτʼ ἀεὶ διὰ βίου παντὸς ἔν τε ᾠδαῖς καὶ μύθοις καὶ λόγοις. εἰ δʼ οὖν ἄλλῃ πῃ δοκεῖ ἢ ταύτῃ, πρὸς ταῦτα οὐδεὶς φθόνος ἀμφισβητῆσαι τῷ λόγῳ.

of how one can, if he tries, persuade the souls of the young of anything, so that the only question he has to consider in his inventing is what would do most good to the State, if it were believed; and then he must devise all possible means to ensure that the whole of the community constantly, so long as they live, use exactly the same language, so far as possible, about these matters, alike in their songs, their tales, and their discourses. If you, however, think otherwise, I have no objection to your arguing in the opposite sense.