Plato, Meno 75d

αὐτῷ ὅτι ἐμοὶ μὲν εἴρηται· εἰ δὲ μὴ ὀρθῶς λέγω, σὸν ἔργον λαμβάνειν λόγον καὶ ἐλέγχειν. εἰ δὲ ὥσπερ ἐγώ τε καὶ σὺ νυνὶ φίλοι ὄντες βούλοιντο ἀλλήλοις διαλέγεσθαι, δεῖ δὴ πρᾳότερόν πως καὶ διαλεκτικώτερον ἀποκρίνεσθαι. ἔστι δὲ ἴσως τὸ διαλεκτικώτερον μὴ μόνον τἀληθῆ ἀποκρίνεσθαι, ἀλλὰ καὶ διʼ ἐκείνων ὧν ἂν προσομολογῇ εἰδέναι ὁ ἐρωτώμενος. πειράσομαι δὴ καὶ ἐγώ σοι οὕτως εἰπεῖν.

I have made my statement; if it is wrong, your business is to examine and refute it. But if, like you and me on this occasion, we were friends and chose to have a discussion together, I should have to reply in some milder tone more suited to dialectic. The more dialectical way, I suppose, is not merely to answer what is true, but also to make use of those points which the questioned person acknowledges he knows. And this is the way in which I shall now try to argue with you. Tell me, is there something you call an end? Such a thing, I mean,