Note 67 — Chapter XXX · POLITIKUS.
Reading edition
Plato, Kratyl. p. 435 B-C.
So in the Protagoras (p. 328 A) we find the Platonic Protagoras comparing the self-originated and self-sustaining traditional ethics, to the traditional language — τίς διδάσκαλός ἐστι τοῦ Ἑλληνίζειν;