Plato, Laws 646c

ἑκὼν ἐπὶ τὸ τοιοῦτον ἀφικνεῖται; πῶς γὰρ οὔ; τί οὖν; τοὺς εἰς τὰ ἰατρεῖα αὐτοὺς βαδίζοντας ἐπὶ φαρμακοποσίᾳ ἀγνοεῖν οἰόμεθα ὅτι μετʼ ὀλίγον ὕστερον καὶ ἐπὶ πολλὰς ἡμέρας ἕξουσιν τοιοῦτον τὸ σῶμα, οἷον εἰ διὰ τέλους ἔχειν μέλλοιεν, ζῆν οὐκ ἂν δέξαιντο; ἢ τοὺς ἐπὶ τὰ γυμνάσια καὶ πόνους ἰόντας οὐκ ἴσμεν ὡς ἀσθενεῖς εἰς τὸ παραχρῆμα γίγνονται; πάντα ταῦτα ἴσμεν. καὶ ὅτι τῆς μετὰ ταῦτα ὠφελίας ἕνεκα ἑκόντες πορεύονται;

got into such a state? Of course we should. Well then, do we suppose that persons who go of themselves to dispensaries to drink medicines are not aware that soon afterwards, and for many days to come, they will find themselves in a bodily condition such as would make life intolerable if it were to last for ever? And we know, do we not, that men who go to the gymnasia for hard training commence by becoming weaker? All this we know. We know also that they go there voluntarily for the sake of the subsequent benefit ?