[822]. Plato, Tim. 40 c 1, (γῆν) φύλακα καὶ δημιουργὸν νυκτός τε καὶ ἡμέρας ἐμηχανήσατο. On the other hand, νὺξ μὲν οὖν ἡμέρα τε γέγονεν οὕτως καὶ διὰ ταῦτα, ἡ τῆς μιᾶς καὶ φρονιμωτάτης κυκλήσεως περίοδος (39 c 1).
[823]. Arist. de Caelo, Β, 13. 293 b 15 sqq.
[824]. Boeckh admitted a very slow motion of the heaven of the fixed stars, which he at first supposed to account for the precession of the equinoxes, though he afterwards abandoned that hypothesis (Untersuchungen, p. 93). But, as Dreyer admits (Planetary Systems, p. 49), it is “not ... necessary with Boeckh to suppose the motion of the starry sphere to have been an exceedingly slow one, as it might in any case escape direct observation.”
[825]. Aet. ii. 20, 13 (Chap. IV. p. 275, [n. 609]); cf. ib. 12 (of Philolaos), ὥστε τρόπον τινὰ διττοὺς ἡλίους γίγνεσθαι, τό τε ἐν τῷ οὐρανῷ πυρῶδες καὶ τὸ ἀπ’ αὐτοῦ πυροειδὲς κατὰ τὸ ἐσοπτροειδές· εἰ μή τις καὶ τρίτον λέξει τὴν ἀπὸ τοῦ ἐνόπτρου κατ’ ἀνάκλασιν διασπειρομένην πρὸς ἡμᾶς αὐγήν. Here τὸ ἐν τῷ οὐρανῷ πυρῶδες is the central fire, in accordance with the use of the word οὐρανός explained in another passage of Aetios, Stob. Ecl. i. p. 196, 18 (R. P. 81). It seems to me that these strange notices must be fragments of an attempt to show how the heliocentric hypothesis arose from the theory of Empedokles as to the sun’s light. The meaning is that the central fire really was the sun, but that Philolaos unnecessarily duplicated it by supposing the visible sun to be its reflexion.
[827]. Aet. i. 7, 7 (R. P. 81). Procl. in Tim. p. 106, 22, Diehl (R. P. 83 e).
[828]. On these points, see Staigmüller, Beiträge zur Gesch. der Naturwissenschaften im klassichen Altertume (Progr., Stuttgart, 1899); and “Herakleides Pontikos und das heliokentrische System” (Arch. xv. pp. 141 sqq.). Though, for reasons which will partly appear from the following pages, I should not put the matter exactly as Staigmüller does, I have no doubt that he is substantially right. Diels had already expressed his adhesion to the view that Herakleides was the real author of the heliocentric hypothesis (Berl. Sitzb., 1893, P. 18).
[829]. In his letter to Pope Paul III., Copernicus quotes Plut. Plac. iii. 13, 2-3 (R. P. 83 a), and adds “Inde igitur occasionem nactus, coepi et ego de terrae mobilitate cogitare.” The whole passage is paraphrased by Dreyer, Planetary Systems, p. 311. Cf. also the passage from the original MS., which was first printed in the edition of 1873, translated by Dreyer, ib. pp. 314 sqq.
[830]. Arist. Met. Α, 5. 986 a 3 (R. P. 83 b).
[831]. Aet. ii. 29, 4, τῶν Πυθαγορείων τινὲς κατὰ τὴν Ἀριστοτέλειον ἱστορίαν καὶ τὴν Φιλίππου τοῦ Ὀπουντίου ἀπόφασιν ἀνταυγείᾳ καὶ ἀντιφράξει τοτὲ μὲν τῆς γῆς, τοτὲ δὲ τῆς ἀντίχθονος (ἐκλείπειν τὴν σελήνην).