Book 2, κ′ περὶ γενῶν καὶ εἰδῶν.

ἀλλ’ εἰ μὲν οὐδέν ἐστιν ὅλως τὸ τὶ, οὐδὲ τὸ γένος, πέρας ἔχει ἡ ζήτησις. εἰ δὲ πάντα εἶναι ῥηθείη, πρὸς τῷ ἀδύνατον εἶναι τὸ λεγόμενον, καὶ τῶν εἰδῶν καὶ τῶν καθ’ ἕκαστον ἐν οἶς ἐστι δεήσει πάντα εἶναι. ὡς γάρ, ἐπεὶ τὸ ζῷον, ὡς φασίν, οὐσία ἐστὶν ἔμψυχος αἰσθητική, ἕκαστον τῶν εἰδῶν αὐτοῦ καὶ οὐσία εἶναι λέγεται καὶ ἔμψυχος καὶ αἰσθητική, οὕτως εἰ τὸ γένος καὶ σῶμά ἐστι καὶ ἀσώματον καὶ ψευδὲς καὶ ἀληθὲς καὶ μέλαν, εἰ τύχοι, καὶ λευκὸν καὶ σμικρότατον καὶ μέγιστον καὶ τἆλλα πάντα, ἕκαστον τῶν εἰδῶν καὶ τῶν ἓκαστον ἕκαστον πάντα ἔσται· ὅπερ οὐ θεωρεῖται. ψεῦδος οὖν καὶ τοῦτο.