James Adam, The Republic of Plato

οὐ ταῦτα κτλ.: ‘do you not suppose they would believe that they were naming these particular passing objects which they saw?’ They have never seen anything of the real παριόντα (or παραφερόμενα): therefore (οὖν) they suppose themselves to be naming, i.e. using the name of, not (as is in point of fact the case) the real παριόντα, but only these παριόντα which they see. For example, they call the shadow of a table ‘a table,’ and in so doing they are, without knowing it, naming, not, as they suppose, the shadow, but the substance. J. and C. remark that “παριόντα is rather confusing as it might signify either the shadows” (cf. 516 C) “or the realities” (cf. 515 D). True: but ταῦτα τὰ παριόντα, ἅπερ ὁρῷεν can signify only the shadows. The corruption παρόντα for παριόντα (see cr. n.) is easy, and occurs in some MSS at 516 C (where παριόντα again=παριοῦσαι σκιαί). Plato means (to interpret the allegory) that what the ἀπαίδευτος calls a substance is only a shadow. For other views of this sentence see App. IV.

εἰ καὶ ἠχὼ κτλ. The voices heard by the ἀπαίδευτος are as shadowy as the forms he sees: βλέποντες ἔβλεπον μάτην, | κλύοντες οὐκ ἤκουον, ἀλλ᾽ ὀνειράτων | ἀλίγκιοι μορφαῖσι τὸν μακρὸν βίον | ἔφυρον εἰκῆ πάντα (Aesch P. V. 447—450).