Plato, Meno 90c

γενέσθαι, παρὰ τίνας ἂν αὐτὸν πέμποιμεν διδασκάλους; ἆρʼ οὐ παρὰ τοὺς ἰατρούς; πάνυ γε. τί δʼ εἰ σκυτοτόμον ἀγαθὸν βουλοίμεθα γενέσθαι, ἆρʼ οὐ παρὰ τοὺς σκυτοτόμους; ναί. καὶ τἆλλα οὕτως; πάνυ γε. ὧδε δή μοι πάλιν περὶ τῶν αὐτῶν εἰπέ. παρὰ τοὺς ἰατρούς, φαμέν, πέμποντες τόνδε καλῶς ἂν ἐπέμπομεν, βουλόμενοι ἰατρὸν γενέσθαι· ἆρʼ ὅταν τοῦτο λέγωμεν, τόδε

to whom should we send him for instruction? Would it not be to the doctors? Certainly. And if we wanted him to become a good cobbler, should we not send him to the cobblers? Yes. And in the same way with every other trade? Certainly. Now let me ask you something more about these same instances. We should be right, we say, in sending him to the doctors if we wanted him to be a doctor.