136 COSMOS. 



According to his theory the moon is a body conglomerated 

 ^like hail) by the action of fire, and receives its light 



ut Empedocles ait, aerem glaciatum, 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 incon- 

 tinently assent thereto, for I am ignorant of what substance 

 the heavens are composed." We have no early Hellenic 

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

 vitreous heaven (ccelum vitreum), for only one celestial body, 

 the sun, is called by Philolaus, 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 reflec- 

 tion of the sun's light from the body of the moon, (supposed 

 to be consolidated in the same manner as hail-stones,) is fre- 

 quently noticed by Plutarch, apud Euaeb. Prcep. Evangel. 1, 

 pag. 24. D, and de facie in orbe Lunce, cap. 5). Where Uranos 

 is described as x a ^ KCOS and atbrjpeos by Homer and Pindar, the 

 expression refers only to the idea of steadfast, permanent, and 

 imperishable^ as in speaking of brazen hearts and brazen 

 voices. Volcker uber Homerische Geographic, 1830, s. 5. 

 The earliest mention before Pliny, of the word Kpvo-raXXos 

 when applied to ice-.ike, transparent rock-crystal occurs in 

 Dionysius Periegetes, 781, Aelian, xv. 8, and Strabo, xv. 

 p. 717, Casaub. The opinion, that the idea of the crystalline 

 heavens being a glacial vault (aer glaciatus of Lactantius) 

 arose amongst the ancients, from their knowledge of the 

 decrease of temperature, with the increase of height in the 

 strata of the atmosphere, as ascertained from ascending great 

 heights and from the aspect of snow-covered mountains, is 

 refuted by the circumstance that they regarded the fiery ether 

 as lying beyond the confines of the actual atmosphere, and 

 the stars as warm bodies. (Aristot., Meteor. 1, 3, de Ccelo, 11, 

 7, p. 289). In speaking of the music of the spheres (Aristot. 

 de Ccelo, 11, p. 290), which according to the views of the 

 Pythagoreans is not perceived by men, because it is con- 

 tinuous, whereas tones can only be heard when they 

 are interrupted by silence, Aristotle singularly enough main- 

 tains that the movement of the spheres generates heat in 

 the air below them while they are themselves not heated. 



