OF THE COSMOS. GROUPING OF THE FIXED STARS. 107 



Philosophers," we carry back the expression of " crystal 

 heaven" to the early time of Anaximenes, we find, however, 

 the idea which forms the groundwork of such an appellation 

 first developed with precision by Empedocles. He regards 

 the heaven of the fixed stars as a solid mass, formed from 

 the aether which has been solidified into a crystalline substance 

 by heat. ( 20 ) The Moon is regarded by him as a body which 

 has been molten as by the action of fire, and subsequently 

 consolidated like hail. The original idea of transparent 

 solidified substances would not, according to the physics of 

 the Ancients, ( 201 ) and their ideas of the solidification of 

 fluids, have led directly to cold and ice ; but the affinity of 

 Kpv<TTa\\oQ with Kpvog and Kpvaraiv^, as well as comparison 

 with the most transparent of all bodies, gave occasion to the 

 more definite statements, that the vault of heaven consisted 

 of ice or of glass. Thus we find in Lactantius " coelum 

 aerem glaciatum esse," and " vitreum cesium." Empedocles 

 was certainly not thinking of Phoenician glass, but of air 

 which, by the action of the fiery aether, had been run together 

 into a transparent solid body. In the comparison with ice 

 (KpvaraXXoQ), the prevailing idea was that of transparency : 

 the origin of ice by the action of cold was not regarded, 

 all that was directly considered being the case of a fluid 

 which had become solid and was transparent. If the poets 

 used the word crystal, in prose (as is testified by the 

 passage of Achilles Tatius, the commentator of Aratus, cited 

 in Note 200,) the expression employed is only crystalline, or 

 similar to crystal (irpvorraAXoet&ye). So also TTUJOQ (from 

 irhyvvoSai, to solidify) signifies a piece of ice, in which the 

 solidification is the only thing considered. 



Through the Fathers of the Church, who, in allusions 



