[Side-note: Astronomy and physics of Anaxagoras.] In describing the formation of the Kosmos, Anaxagoras supposed that, as a consequence of the rotation initiated by mind, the primitive chaos broke up. "The Dense, Wet, Cold, Dark, Heavy, came together into the place where now Earth is: Hot, Dry, Bare, Light, Bright, departed to the exterior region of the revolving Æther."[167] In such separation each followed its spontaneous and inherent tendency. Water was disengaged from air and clouds, earth from water: earth was still farther consolidated into stones by cold.[168] Earth remained stationary in the centre, while fire and air were borne round it by the force and violence of the rotatory movement. The celestial bodies--Sun, Moon, and Stars--were solid bodies analogous to the earth, either caught originally in the whirl of the rotatory movement, or torn from the substance of the earth and carried away into the outer region of rotation.[169] They were rendered hot and luminous by the fiery fluid in the rapid whirl of which they were hurried along. The Sun was a stone thus made red-hot, larger than Peloponnesus: the Moon was of earthy matter, nearer to the Earth, deriving its light from the Sun, and including not merely plains and mountains, but also cities and inhabitants.[170] Of the planetary movements, apart from the diurnal rotation of the celestial sphere, Anaxagoras took no notice.[171] He explained the periodical changes in the apparent course of the sun and moon by resistances which they encountered, the former from accumulated and condensed air, the latter from the cold.[172] Like Anaximenes and Demokritus, Anaxagoras conceived the Earth as flat, round in the surface, and not deep, resting on and supported by the air beneath it. Originally (he thought) the earth was horizontal, with the axis of celestial rotation perpendicular, and the north pole at the zenith, so that this rotation was then lateral, like that of a dome or roof; it was moreover equable and unchanging with reference to every part of the plane of the earth's upper surface, and distributed light and heat equally to every part. But after a certain time the Earth tilted over of its own accord to the south, thus lowering its southern half, raising the northern half, and causing the celestial rotation to appear oblique.[173] [Footnote 167: Anaxag. Fr. 19, p. 131, Schaub.; compare Fr. 6, p. 97; Diogen. Laert. ii. 8.] [Footnote 168: Anaxag. Fr. 20, p. 133, Schau.] [Footnote 169: See the curious passage in Plutarch, Lysander 12, and Plato, Legg. xii. p. 967 B; Diogen. Laert. ii. 12; Plutarch, Placit. Philos. ii. 13.] [Footnote 170: Plato, Kratylus, p. 409 A; Plato, Apol. Sok. c. 14; Xenophon, Memorab. iv. 7.] [Footnote 171: Schaubach, ad Anax. Fr. p. 165.] [Footnote 172: Plutarch, Placit. Philosoph. ii. 23.]