Plato, Meno 77a

ἀλλὰ περιμένοιμʼ ἄν, ὦ Σώκρατες, εἴ μοι πολλὰ τοιαῦτα λέγοις. ἀλλὰ μὴν προθυμίας γε οὐδὲν ἀπολείψω, καὶ σοῦ ἕνεκα καὶ ἐμαυτοῦ, λέγων τοιαῦτα· ἀλλʼ ὅπως μὴ οὐχ οἷός τʼ ἔσομαι πολλὰ τοιαῦτα λέγειν. ἀλλʼ ἴθι δὴ πειρῶ καὶ σὺ ἐμοὶ τὴν ὑπόσχεσιν ἀποδοῦναι, κατὰ ὅλου εἰπὼν ἀρετῆς πέρι ὅτι ἐστίν, καὶ παῦσαι πολλὰ ποιῶν ἐκ τοῦ ἑνός, ὅπερ φασὶ τοὺς συντρίβοντάς τι ἑκάστοτε οἱ σκώπτοντες, ἀλλὰ ἐάσας ὅλην καὶ ὑγιῆ εἰπὲ τί ἐστιν ἀρετή. τὰ δέ γε παραδείγματα

But I should stay, Socrates, if you would give me many such answers. Well then, I will spare no endeavor, both for your sake and for my own, to continue in that style; but I fear I may not succeed in keeping for long on that level. But come now, you in your turn must try and fulfil your promise by telling me what virtue is in a general way; and you must stop producing a plural from the singular, as the wags say whenever one breaks something, but leave virtue