James Adam, The Republic of Plato

τοῦτον after τοῦτο is needed to balance αὐτό (cf. 511 E): in construction, it depends, like ὅν, on ἐγέννησεν (Schneider). τοῦτο itself, like ἀνάλογον ἑαυτῷ, is predicative (‘ut hoc esset’). Stallbaum erroneously supplies φάναι με λέγειν to govern τοῦτον.

ὧν ἂν -- ἐπέχῃ . ἐπέχῃ ‘occupat’ as in the Homeric ἑπτὰ δ᾽ ἐπέσχε πέλεθρα and the like. With ἐπί of light cf. Mimn. 2. 8 ἐπὶ γῆν κίδναται ἠέλιος. The Greek will not admit of D. and V.'s translation ‘upon which the light of day is shedding colour’; and Plato moreover, both here and in Tim. 67 C, looks on Colour as something inherent in the Object, not imparted by Light, although Light is of course necessary in order to see it. Cf. 507 D note

φῶς -- φέγγη: ‘lux — lumina.’ The words are constantly interchanged, but, when contrasted with φέγγος, φῶς denotes a natural or primary, φέγγος an artificial or derivative light. See Neil on Ar. Knights 1319. Plato knew that the Moon's light is borrowed from the Sun (X 616 E).

ὧν ὁ ἥλιος κτλ. ‘The Sun’ is here said loosely for ‘the Sunlight’ or ‘light of Day’ (τὸ ἡμερινὸν φῶς above); for, as appears from 508 E, 508 A, it is not the Sun, but Light, which is to be equated with Truth and Being (οὗ καταλάμπει ἀλήθειά τε καὶ τὸ ὄν in D). See also on τοῦτο τοίνυν κτλ. in 508 D. Instead of καταλάμπει, καταλάμπῃ is read by a majority of editors, with several MSS, including Ξ: but ὅς for ὃς ἄν is, to say the least, extremely rare in prose, and the corruption καταλάμπῃ was easy after ὅταν. καταλάμπει was, if I mistake not, originally the reading of A (see cr. n.), and is at least as well supported by the other MSS as καταλάμπῃ. J. and C., reading καταλάμπῃ, strangely observe that ‘ἄν would be felt as superfluous after ὅταν.’