Plato, Meno 73e

πότερον ἀρετή, ὦ Μένων, ἢ ἀρετή τις; πῶς τοῦτο λέγεις; ὡς περὶ ἄλλου ὁτουοῦν. οἷον, εἰ βούλει, στρογγυλότητος πέρι εἴποιμʼ ἂν ἔγωγε ὅτι σχῆμά τί ἐστιν, οὐχ οὕτως ἁπλῶς ὅτι σχῆμα. διὰ ταῦτα δὲ οὕτως ἂν εἴποιμι, ὅτι καὶ ἄλλα ἔστι σχήματα. ὀρθῶς γε λέγων σύ, ἐπεὶ καὶ ἐγὼ λέγω οὐ μόνον δικαιοσύνην ἀλλὰ καὶ ἄλλας εἶναι ἀρετάς.

Virtue, Meno, or a virtue? What do you mean by that? What I would in any other case. To take roundness, for instance; I should call it a figure, and not figure pure and simple. And I should name it so because there are other figures as well. You would be quite right—just as I say there are other virtues besides justice.