Note 10 — Chapter XXVIII · THEÆTETUS.
Reading edition
Plato, Theætêt. pp. 151 E — 152 A.
Theætêt. οὐκ ἄλλο τί ἐστιν ἐπιστήμη ἢ αἴσθησις.…
Sokrat. Κινδυνεύεις μέντοι λόγον οὐ φαῦλον εἰρηκέναι περὶ ἐπιστήμης, ἀλλ’ ὅν ἔλεγε καὶ Πρωταγόρας· τρόπον δέ τινα ἄλλον εἴρηκε τὰ αὐτὰ ταῦτα. Φησὶ γάρ που — Πάντων χρημάτων μέτρον ἄνθρωπον εἶναι, τῶν μὲν ὄντων, ὡς ἔστι — τῶν δὲ μὴ ὄντων, ὡς οὐκ ἔστιν. Ἀνέγνωκας γάρ που;
Theætêt. Ἀνέγνωκα καὶ πολλάκις.
Sokrat. Οὐκοῦν οὕτω πως λέγει, ὠς οἷα μὲν ἕκαστα ἐμοὶ φαίνεται, τοιαῦτα μέν ἐστιν ἐμοὶ — οἷα δὲ σοί, τοιαῦτα δὲ αὖ σοί· ἀνθρωπος δὲ σύ τε κἀγώ.
Theætêt. Λέγει γὰρ οὖν οὕτως.
Here Plato appears to transcribe the words of Protagoras (compare p. 161 B, and the Kratylus, p. 386 A) which distinctly affirm the doctrine of Homo Mensura — Man is the measure of all things, — but do not affirm the doctrine, that knowledge is sensible perception. The identification between the two doctrines is asserted by Plato himself. It is Plato who asserts “that Protagoras affirmed the same doctrine in another manner,” citing afterwards the manner in which he supposed Protagoras to affirm it. If there had been in the treatise of Protagoras any more express or peremptory affirmation of the doctrine “that knowledge is sensible perception,” Plato would probably have given it here.