Note 585 — Chapter LXVII · THE DRAMA. — RHETORIC AND DIALECTICS. — THE SOPHISTS.

Plato, Theætet. 18, p. 164, E. Οὔτι ἄν, οἶμαι, ὦ φίλε, εἴπερ γε ὁ πατὴρ τοῦ ἑτέρου μύθου ἔζη—ἀλλὰ πολλὰ ἂν ἤμυνε· νῦν δὲ ὄρφανον αὐτὸν ὄντα ἡμεῖς προπηλακίζομεν ... ἀλλὰ δὴ αὐτοὶ κινδυνεύσομεν τοῦ δικαίου ἕνεκ᾽ αὐτῷ βοηθεῖν.

This theory of Protagoras is discussed in the dialogue called Theætetus, p. 152, seq., in a long but desultory way.

See Sextus Empiric. Pyrrhonic. Hypol. i. 216-219, et contra Mathematicos, vii, 60-64. The explanation which Sextus gives of the Protagorean doctrine, in the former passage, cannot be derived from the treatise of Protagoras himself; since he makes use of the word ὕλη in the philosophical sense, which was not adopted until the days of Plato and Aristotle.

It is difficult to make out what Diogenes Laërtius states about other tenets of Protagoras, and to reconcile them with the doctrine of “man being the measure of all things,” as explained by Plato (Diog. Laërt. ix, 51, 57).