James A. Towle, Commentary on Plato: Protagoras
James A. Towle, Ed.

ἀνθρώποις μὲν κτἑ.: Protagoras here gives a long disquisition upon the relative nature of the useful which probably recalled actual discourses of his (see on 351 c), but he becomes confused in endeavoring to drag in much which should be kept separate. He has denied that the absolutely useless is good (οὐδαμῶς), but adds that he knows of much which is injurious to men, but beneficial to animals or plants. As he now begins with ἀνθρώποις μὲν ἀνωφελῆ, it occurs to him that all things fall into three classes, the useful, the harmful and the neutral, so he adds to his first class τὰ δὲ γὲ ὠφέλιμα, τὰ δὲ οὐδέτερα. By adding, with the last, ἀνθρώποις μέν, he returns to his opening thought, but continues only with ἵπποις δέ, failing to add the ὠφέλιμα, because it is so vividly in his mind as the object of his discourse. —

ἀνωφελῆ: prop. useless, not infreq. harmful. Cf. Rep. viii. 560 d μετὰ πολλῶν καὶ ἀνωφελῶν ἐπιθυμιῶν, of which it had before been said 559 a οὐδὲν ἀγαθὸν ἐνοῦσαι δρῶσιν, αἱ δὲ καὶ τοὐναντίον.

οὐδενί: since species are spoken of, οὐδέσι might have been used (cf. Euthyd. 305 d), but whatever is denied of each individual must be denied also of the species. Cf. Dem. XIX. 66 and 62.