Plato, Meno 74a

τίνας ταύτας; εἰπέ. οἷον καὶ ἐγώ σοι εἴποιμι ἂν καὶ ἄλλα σχήματα, εἴ με κελεύοις· καὶ σὺ οὖν ἐμοὶ εἰπὲ ἄλλας ἀρετάς. ἡ ἀνδρεία τοίνυν ἔμοιγε δοκεῖ ἀρετὴ εἶναι καὶ σωφροσύνη καὶ σοφία καὶ μεγαλοπρέπεια καὶ ἄλλαι πάμπολλαι. πάλιν, ὦ Μένων, ταὐτὸν πεπόνθαμεν· πολλὰς αὖ ηὑρήκαμεν ἀρετὰς μίαν ζητοῦντες, ἄλλον τρόπον ἢ νυνδή· τὴν δὲ μίαν, ἣ διὰ πάντων τούτων ἐστίν, οὐ δυνάμεθα ἀνευρεῖν. οὐ γὰρ δύναμαί πω, ὦ Σώκρατες, ὡς σὺ ζητεῖς,

What are they? Tell me. In the same way as I can tell you of other figures, if you request me, so do you tell me of other virtues. Well then, courage, I consider, is a virtue, and temperance, and wisdom, and loftiness of mind; and there are a great many others. Once more, Meno, we are in the same plight: again we have found a number of virtues when we were looking for one, though not in the same way as we did just now; but the one that runs through them all, this we are not able to find.