Plato, Laws 663c

ἀφελών, καὶ πείσει ἁμῶς γέ πως ἔθεσι καὶ ἐπαίνοις καὶ λόγοις ὡς ἐσκιαγραφημένα τὰ δίκαιά ἐστι καὶ ἄδικα, τὰ μὲν ἄδικα τῷ τοῦ δικαίου ἐναντίως φαινόμενα, ἐκ μὲν ἀδίκου καὶ κακοῦ ἑαυτοῦ θεωρούμενα ἡδέα, τὰ δὲ δίκαια ἀηδέστατα, ἐκ δὲ δικαίου πάντα τἀναντία παντὶ πρὸς ἀμφότερα. φαίνεται. τὴν δʼ ἀλήθειαν τῆς κρίσεως ποτέραν κυριωτέραν εἶναι φῶμεν; πότερα τὴν τῆς χείρονος ψυχῆς ἢ τὴν τῆς βελτίονος;

and by one means or another—habituation, commendation, or argument—will persuade people that their notions of justice and injustice are illusory pictures, unjust objects appearing pleasant and just objects most unpleasant to him who is opposed to justice, through being viewed from his own unjust and evil standpoint, but when seen from the standpoint of justice, both of them appear in all ways entirely the opposite. So it appears. In point of truth, which of the two judgements shall we say is the more authoritative,—that of the worse soul or that of the better. That of the better, undoubtedly.