J. Adam, A. M. Adam, Commentary on Plato, Protagoras
J. Adam & A. M. Adam, Ed.

59. ἡ μετρητικὴ τέχνη. See Introduction, p. xxix.

60. ἢ ἡ τοῦ φαινομένου δύναμις. ἤ is omitted in B and T. ‘The power of that which appears’ is its power to affect us.

61. ἐπλάνα καὶ ἐποίει κτλ. ἄν is not to be supplied. Plato is reverting to the illustration in C. The imperfect is idiomatic for ‘causes us, as we saw, to wander’, etc. (viz. because τὰ αὐτὰ μεγέθη seem to us both μείζω and ἐλάττω): it is what Goodwin calls the ‘philosophic imperfect’: cf. Crito, 47D διαφθεροῦμεν ἐκεῖνο καὶ λωβησόμεθα, ὃ τῷ μὲν δικαίῳ βέλτιον ἐγίγνετο (becomes as we saw), τῶ̣ δὲ ἀδίκω̣ ἀπώλλυτο. By adding καὶ ἐν ταῖς πράξεσιν —σμικρῶν Plato treats his hypothesis that εὖ πράττειν is to select μεγάλα μήκη as a fact; he does so also in ἂν ἐποίησε κτλ. i.e. ‘would have made’, viz. if we had made use of it, but we did not. If the hypothesis were still treated as a hypothesis, we should have had ἂν ἐποίει (and not ἂν ἐποίησε) to correspond to what would then have been ἂν (expressed or understood) ἐπλάνα καὶ ἐποίει.

ἄνω τε καὶ κάτω. ἄνω κάτω (Theaet. 195C) and ἄνω καὶ κάτω (Gorg. 495A) are other forms of this proverbial phrase.