Plato, Meno 90d

λέγομεν, ὅτι παρὰ τούτους πέμποντες αὐτὸν σωφρονοῖμεν ἄν, τοὺς ἀντιποιουμένους τε τῆς τέχνης μᾶλλον ἢ τοὺς μή, καὶ τοὺς μισθὸν πραττομένους ἐπʼ αὐτῷ τούτῳ, ἀποφήναντας αὑτοὺς διδασκάλους τοῦ βουλομένου ἰέναι τε καὶ μανθάνειν; ἆρʼ οὐ πρὸς ταῦτα βλέψαντες καλῶς ἂν πέμποιμεν; ναί. οὐκοῦν καὶ περὶ αὐλήσεως καὶ τῶν ἄλλων τὰ αὐτὰ

When we say this, do we mean that we should be wise in sending him to those who profess the art rather than those who do not, and to those who charge a fee for the particular thing they do, as avowed teachers of anyone who wishes to come and learn of them? If these were our reasons, should we not be right in sending him? Yes. And the same would hold in the case of flute-playing, and so on with the rest? What folly, when we wanted to make someone a flute-player,