Plato, Laws 820d

ἴσως· ἔοικεν γοῦν ἥ τε πεττεία καὶ ταῦτα ἀλλήλων τὰ μαθήματα οὐ πάμπολυ κεχωρίσθαι. ταῦτα τοίνυν ἐγὼ μέν, ὦ Κλεινία, φημὶ τοὺς νέους δεῖν μανθάνειν· καὶ γὰρ οὔτε βλαβερὰ οὔτε χαλεπά ἐστιν, μετὰ δὲ παιδιᾶς ἅμα μανθανόμενα ὠφελήσει μέν, βλάψει δὲ ἡμῖν τὴν πόλιν οὐδέν. εἰ δέ τις ἄλλως λέγει, ἀκουστέον. πῶς δʼ οὔ; ἀλλὰ μὴν ἂν οὕτω ταῦτα ἔχοντα φαίνηται, δῆλον ὡς ἐγκρινοῦμεν αὐτά, μὴ ταύτῃ δὲ φαινόμενα ἔχειν ἀποκριθήσεται.

No doubt. And, after all, draughts and these studies do not seem to be so very far apart. I assert, then, Clinias, that these subjects must be learnt by the young; for they are, in truth, neither harmful nor hard, and when learnt by way of play they will do no damage at all to our State, but will do it good. Should anyone disagree, however, we must listen to him. Of course. Well then, if this is clearly the case, obviously we shall adopt these subjects; but if it seems clearly to be otherwise, we shall rule them out.