Plato, Meno 95c

καὶ Γοργίου μάλιστα, ὦ Σώκρατες, ταῦτα ἄγαμαι, ὅτι οὐκ ἄν ποτε αὐτοῦ τοῦτο ἀκούσαις ὑπισχνουμένου, ἀλλὰ καὶ τῶν ἄλλων καταγελᾷ, ὅταν ἀκούσῃ ὑπισχνουμένων· ἀλλὰ λέγειν οἴεται δεῖν ποιεῖν δεινούς. οὐδʼ ἄρα σοὶ δοκοῦσιν οἱ σοφισταὶ διδάσκαλοι εἶναι; οὐκ ἔχω λέγειν, ὦ Σώκρατες. καὶ γὰρ αὐτὸς ὅπερ οἱ πολλοὶ πέπονθα· τοτὲ μέν μοι δοκοῦσιν, τοτὲ δὲ οὔ. οἶσθα δὲ ὅτι οὐ μόνον σοί τε καὶ τοῖς ἄλλοις τοῖς πολιτικοῖς τοῦτο δοκεῖ τοτὲ μὲν εἶναι διδακτόν, τοτὲ δʼ οὔ,

to be teachers of virtue? That is a point, Socrates, for which I admire Gorgias: you will never hear him promising this, and he ridicules the others when he hears them promise it. Skill in speaking is what he takes it to be their business to produce. Then you do not think the sophists are teachers of virtue? I cannot say, Socrates. I am in the same plight as the rest of the world: sometimes I think that they are, sometimes that they are not. And are you aware that not only you and other political folk