THE FIXED STARS 123 



to the crystalline heavens ; the planets (darpa nhavufjiEva 

 or ixXavTrra), which move in an opposite direction, belong to 

 a lower and nearer region."* As we find in Manilius, in 

 the earliest ages of the Caesars, that the term Stella Jixa was 

 substituted for infixa or affixa, it may be assumed that the 

 schools of Rome attached thereto at first only the original 

 signification of riveted ; but as the word fixus also embraced 

 the idea of immobility, and might even be regarded as sy» 

 nonymous with immotus and immobilis, we may readily con- 

 ceive that the national opinion, or, rather, usage of speech, 

 should gradually have associated with Stella Jixa the idea of 

 immobility, without reference to the fixed sphere to which it 

 was attached. In this sense Seneca might term the world 

 of the fixed stars fixum et immobilem populum. 



Although, according to Stobseus, and the collector of the 

 " Views of the Philosophers," the designation " crystal vault 

 of heaven" dates as far back as the early period of Anax- 

 imenes, the first clearly-defined signification of the idea on 

 which the term is based occurs in Empedocles. This phi- 

 losopher regarded the heaven of the fixed stars as a solid 

 mass, formed from the ether which had been rendered crys- 

 talline and rigid by the action of nre.f According to his 



* According to Democritus and his disciple Metrodorus, Stob., Eclog. 

 Phys., p. 582. 



t Plut., De plac. Phil., ii., 11; Diog. Laert., viii., 77; Achilles Tat., 

 ad. Arat., cap. 5, E/Z7T, Kpyaraklurj tovtov (tov ovpavbv) eival tyrjaiv, ek 

 tov izayerudovc avXkeyevra ; in like manner, we only meet with the 

 expression crystal-like in Diog. Laert., viii., 77, and Galenus, Hist. Phil., 

 12 (Sturz, Empedocles Agrigent., t. i., p. 321). Lactantius, De Opificio 

 Dei, c. 17 : " An, si mihi quispiam dixerit ceneum esse coelum, aut vi- 

 treum, aut, ut Empedocles ait, agrem glacialum, statimne assentiat quia 

 caelum ex qua materia sit, ignorem." " If any one were to tell me that 

 the heavens are made of brass, or of glass, or, as Empedocles asserts, 

 of frozen air, I should incontinently assent thereto, for I am ignorant of 

 what substance the heavens are composed." We have no early Hel- 

 lenic testimony of the use of this expression of a glass-like or vitreous 

 heaven (cesium vitreum), for only one celestial body, the sun, is called 

 by Philolalis a glass-like body, which throws upon us the rays it has 

 received from the central fire. (The view of Empedocles, referred 

 to in the text, of the reflection of the sun's light from the body of the 

 moon (supposed to be consolidated in the same manner as hailstones) 

 is frequently noticed by Plutarch, apud Euseb. Prcep. Evangel., 1, p. 

 24, D, and De Facie in Orbe Lunce, cap. 5.) Where Uranos is described 

 as ^a/Ueoc and ai6fjpeoc by Homer and Pindar, the expression refers 

 only to the idea of steadfast, permanent, and imperishable, as in speak- 

 ing of brazen hearts and brazen voices. VSlcker uber Homerische Geo- 

 graphic, 1830, s. 5. The earliest mention, before Pliny, of the word 

 KpvoTaXkoc when applied to ice- like, transparent rock-crystal, occurs ia 

 Dionysius Periegetes, 781, iElian, xv., 8, and Strabo, xv... p. 717 Car 



