Note 23 — Chapter XXVIII · THEÆTETUS.
Reading edition
Plato, Phædon, pp. 76-77. ἴση ἀνάγκη ταῦτά τε (Ideas or Forms) εἶναι, καὶ τὰς ἡμετέρας ψυχὰς πρὶν καὶ ἡμᾶς γεγονέναι — καὶ εἰ μὴ ταῦτα, οὐδὲ τάδε. Ὑπερφυῶς, ἔφη ὁ Σιμμίας, δοκεῖ μοι ἡ αὐτὴ ἀνάγκη εἶναι, καὶ εἰς καλόν γε καταφεύγει ὁ λόγος εἰς τὸ ὁμοίως εἶναι τήν τε ψυχὴν ἡμῶν πρὶν γενέσθαι ἡμᾶς καὶ τὴν οὐσίαν ἣν σὺ νῦν λέγεις.
Compare p. 92 E of the same dialogue with the notes of Wyttenbach and Heindorf — “Haec autem οὐσία Idearum, rerum intelligibilium, αὐτῆς ἐστὶν (sc. τῆς ψυχῆς) ut hoc loco dicitur, est propria et possessio animæ nostræ,” &c.
About the essential implication of Νοῦς with the Νοητά, as well as of τὸ δόξαζον with τὰ δοξαζόμενα, and of τὸ αἰσθανόμενον with τὰ αἰσθητά, see Plutarch, De Animæ Procreat. in Timæo, pp. 1012-1024; and a curious passage from Joannes Philoponus ad Aristot. Physica, cited by Karsten in his Commentatio De Empedoclis Philosophiâ, p. 372, and Olympiodorus ad Platon. Phædon, p. 21. τὸν νοῦν φαμὲν ἀκριβῶς γινώσκειν, διότι αὐτός ἐστι τὸ νοητόν.
Sydenham observes, in a note upon his translation of the Philêbus (note 76, p. 118), “Being Intelligent and Being Intelligible are not only correlatives, but are so in their very essence: neither of them can be at all, without the Being of the other”.