Plato, Alcibiades 1, Alcibiades 2, Hipparchus, Lovers, Theages, Charmides, Laches, Lysis, Ἀλκιβιάδησ α 85:

δέδοικα μὲν ἔγωγε ἤδη περὶ ἐμαυτοῦ, οἶμαι μέντοι τὰ αὐτά. οὐκοῦν ὅτι οἶσθα; τοῦτ’ αἴτιον; οἶμαι ἔγωγε. περὶ ὧν ἄρα ἄκων τἀναντία ἀποκρίνῃ, δῆλον ὅτι περὶ τούτων οὐκ οἶσθα. εἰκόσ γε. οὐκοῦν καὶ περὶ τῶν δικαίων καὶ ἀδίκων καὶ καλῶν καὶ αἰσχρῶν καὶ κακῶν καὶ ἀγαθῶν καὶ συμφερόντων καὶ μὴ ἀποκρινόμενοσ φῂσ πλανᾶσθαι; εἶτα οὐ δῆλον ὅτι διὰ τὸ μὴ εἰδέναι περὶ αὐτῶν, διὰ ταῦτα πλανᾷ;