THE PLANETS. 89 



small planets. In the comparative contemplation of these 

 subjects, it is consistent with the nature of this work to be- 

 stow especial attention upon the selection of the numerical 

 relations, which, at the period in which these pages appear, 

 are considered to be the most accurate, i. e., the results of 

 the most recent and reliable investigations. 



a. PRINCIPAL PLANETS. 



1 . Number and Epoch of Discovery. Of the seven cos- 

 mical bodies which, from the most remote antiquity, have 

 been distinguished by their constantly varying relative po- 

 sition toward each other from those which apparently main- 

 tain the same positions and distances the scintillating stars 

 of the region of fixed stars [orbis inerrans] there are only five 

 which appear star-like, " quinque Stella errantes ;" they are 

 Mercury, Venus, Mars, Jupiter, and Saturn. The Sun and 

 the Moon remained almost separated from the others, since 

 they form large disks, and also on account of the greater 

 importance attached to them in accordance with religious 

 myths.* Thus, according to Diodorus (ii., 30), the Chaldeans 

 were acquainted with only five planets. Plato also says 

 distinctly in the Timceus, where he only once mentions the 

 planets, "Round the Earth, fixed in the center of the Cosmos, 

 move the Moon, the Sun, and jive other stars, which have 

 received the name of planets ; the whole, therefore, in seven 

 revolutions."! In the old Pythagorean representation of the 

 celestial system, according to Philolaus, the five planets were 

 mentioned in a similar manner among the ten deified bod- 

 ies which revolve round the central fire (the focus of the 

 universe, earia) " immediately beneath the region of fixed 

 stars ;"$ these were succeeded by the Sun, Moon, Earth, and 

 the avri'xQuv (the anti-Earth). Even Ptolemy always speaks 

 of only five planets. The enumeration of the planets in sys- 

 tems of seven, as Julius Firmicus distributed them among the 

 decani, as they are represented in the zodiacal circle of Bi- 



* Gesenius, in the Hallischen Litteratur-Zeitung, 1822, Nos. 101 and 

 102 (Supplement, p. 801-812). Among the Chaldeans, the Sun aud 

 Moon were held to be the two principal deities ; the five planets mere- 

 ly represented genii. 



t Plato, in the Timceus, p. 38, Steph. ; Davis's translation, ed. Bohn, 

 p. 342. 



\ Bockh, De Platonico systemate Ccelestivm globorum et de vera in- 

 dole astronomies Philolaicce, p. xvii., and the same in Philolaus, 1819, 

 p. 99. 



Jul. Firmicus Maternus, Astron., libri viii. (ed. Pruckner, Basil 

 1551), lib. ii., cap. 4, of the time of Constantino the Great. 



