Arist. _Phys._ Θ, 5. 256 b 24, διὸ καὶ Ἀναξαγόρας ὀρθῶς λέγει, τὸν νοῦν ἀπαθῆ φάσκων καὶ ἀμιγῆ εἶναι, ἐπειδήπερ κινήσεως ἀρχὴν αὐτὸν ποιεῖ εἶναι· οὕτω γὰρ ἂν μόνως κινοίη ἀκίνητος ὢν καὶ κρατοίη ἀμιγῆς ὤν. This is only quoted for the meaning of κρατεῖν. Of course, the words ἀκίνητος ὤν are not meant to be historical, and still less is the interpretation in _de An._ Γ, 4. 429 a 18. Diogenes of Apollonia (fr. 5) couples ὑπὸ τούτου πάντα κυβερνᾶσθαι (the old Milesian word) with πάντων κρατεῖν. Footnote 706: If we retain the MS. εἰδέναι in fr. 1. In any case, the name τὸ σοφόν implies as much. Footnote 707: See fr. 3, 5. Footnote 708: Zeller, p. 993. The truth probably is that Anaxagoras substituted Nous for the Love and Strife of Empedokles, because he wished to retain the old Ionic doctrine of a substance that “knows” all things, and to identify this with the new theory of a substance that “moves” all things. Perhaps, too, it was his increased interest in physiological as distinguished from purely cosmological matters that led him to speak of Mind rather than Soul. The former word certainly suggests design more clearly than the latter. But, in any case, the originality of Anaxagoras lies far more in the theory of matter than in that of Nous. [Sidenote: Formation of the worlds.] 133. The formation of a world starts with a rotatory motion which Nous imparts to a portion of the mixed mass in which “all things are together” (fr. 13), and this rotatory motion gradually extends over a wider and wider space. Its rapidity (fr. 9) produced a separation of the rare and the dense, the cold and the hot, the dark and the light, the moist and the dry (fr. 15). This separation produces two great masses, the one consisting of the rare, hot, light, and dry, called the “Aether”; the other, in which the opposite qualities predominate, called “Air” (fr. 1). Of these the Aether or Fire[709] took the outside while the Air occupied the centre (fr. 15). Footnote 709: Note that Anaxagoras says “air” where Empedokles usually said “aether,” and that “aether” is with him equivalent to fire. Cf. Arist. _de Caelo_, Γ, 3. 302 b 4, τὸ γὰρ πῦρ καὶ τὸν αἰθέρα προσαγορεύει ταὐτό; and _ib._ Α, 3. 270 b 24, Ἀναξαγόρας δὲ καταχρῆται τῷ ὀνόματι τούτῳ οὐ καλῶς· ὀνομάζει γὰρ αἰθέρα ἀντὶ πυρός.