μὴ φάναι . . . ἐὰν μή: generic conditional of the present. The first μή is due to the infinitive.
11 f.
ἀντ᾽ εὖ ποιεῖν: the old way of writing was ἀντευποιεῖν; but a verb can retain its original form only when compounded with a preposition. See H. 581. Gratitude is only a kind of justice.
ὥστε καλὸν δοκεῖ τὸ σημεῖον εἶναι: sc. as testimony to the fact that the teacher has really made him better. The common form of the conditional, where the second member is the converse of the first, is ἐὰν μὲν . . . εἰ δὲ μή. See on 502 b. The use of εἰ with fut. indic. also in the first member emphasizes the rarity of the case. The subject of εὖ ποιήσας is indefinite, ‘any one,’ as of μὴ φάναι above.
