Plato, Laws 667c

δὲ ὀρθότητά τε καὶ ὠφελίαν, ὅπερ ὑγιεινὸν τῶν προσφερομένων λέγομεν ἑκάστοτε, τοῦτʼ αὐτὸ εἶναι ἐν αὐτοῖς καὶ τὸ ὀρθότατον. πάνυ μὲν οὖν. καὶ μὴν καὶ τῇ μαθήσει παρακολουθεῖν μὲν τό γε τῆς χάριτος, τὴν ἡδονήν, τὴν δὲ ὀρθότητα καὶ τὴν ὠφελίαν καὶ τὸ εὖ καὶ τὸ καλῶς τὴν ἀλήθειαν εἶναι τὴν ἀποτελοῦσαν. ἔστιν οὕτως. τί δὲ τῇ τῶν ὁμοίων ἐργασίᾳ ὅσαι τέχναι εἰκαστικαί;

but as regards their correctness and utility, what we call the wholesomeness of each article administered is precisely the most perfect element they contain. Certainly. Learning, too, is accompanied by the element of charm, which is pleasure; but that which produces its correctness and utility, its goodness and nobleness, is truth. Quite so.