James Adam, The Republic of Plato

καὶ αὖ: rursusque (Ficinus), i.e. sicuti et contra, as Ast observes.

εἰ μὲν οὖν -- λέγοι. This difficult passage has suffered severely at the hands of critics, but the text is probably nearly, if not quite, sound. If we take the words as they stand in A, they mean, broadly speaking, that if we are making true guardians, and he (ὁ ἐκεῖνο λέγων means the τις in 419 A) is making something different, he cannot, like ourselves, be speaking of a πόλις, but of something else. This is logical and gives an excellent sense: cf. 422 E εὐδαίμων εἶ— ὅτι οἴει ἄξιον εἶναι ἄλλην τινὰ προσειπει_ν πόλιν ἢ τὴν τοιαύτην οἵαν ἡμεῖς κατεσκευάζομεν. Now we are making guardians in the true sense of the term, such as are least likely to harm the city; whereas the author of the other proposals is making (not guardians, but since he gives them ἀγροί 419 A) a sort of farmers (cf. III 417 B οἰκονόμοι μὲν καὶ γεωργοὶ ἀντὶ φυλάκων ἔσονται) and men who do harm their city, because they “for their bellies' sake, Creep, and intrude and climb into the fold.” The advocates of such a theory must mean something different from a city—something like the “shearers' feast” in Lycidas: cf. I 343 A note γεωργούς is possibly corrupt; if so, I think we should read λεωργούς to contrast with ἥκιστα κακουργούς. The word occurs in the Memorabilia, if not in Plato. See Cl. Rev. X p. 385. Other emendations are enumerated in App. I.

ἐκεῖνο κτλ.: i.e. to pursue the other policy, which we enjoin. ἐκεῖνο does more than merely anticipate ὅπως— ἔσονται.