PORTION OF THE COSMOS. COSMICAL SPACE. 33 



are not a vacuum, ( 60 ) but are filled with some kind of matter, 

 as not only the propagation of light, but also a particular 

 effect of its enfeeblement, as well as'-the influence of a resisting 

 medium on the period of revolution of Encke's comet, and the 

 dissolution of many vast tails of comets, appear to shew, it 

 is necessary to take the precaution of reminding the reader 

 that the term " ether" now employed, and which has come 

 to us from the earliest south and west Asiatic antiquity, has 

 not during so many centuries always conveyed the same 

 ideas. With the Indian philosophers the aether (aka'sa) is 

 one of the " pantschata" or five elements, a fluid of infinite 

 rarity pervading the entire universe, and the exciter of life, 

 as well as the medium of the propagation of sound. ( 61 ) 

 Etymologically, "aka'sa" signifies, according to Bopp, 

 " shining," and therefore in its original meaning ap- 

 proaches the aether of the Greeks as nearly as " shining" 

 does "burning/' 



This aether (aidrjp), according to the dogmas of the 

 Ionian philosophy, and according to Anaxagoras and Empe- 

 docles, was altogether different from the thicker (denser), 

 vapour-filled, true air (a*7p), which surrounds the earth " and 

 perhaps extends to the moon." It was "of a fiery nature, 

 a pure fiery atmosphere, bright beaming ( 62 ), of great tenuity 

 (rarity) and eternal serenity." The etymological de- 

 rivation from " burning" (cufeiv) accords perfectly with 

 this definition. Singularly enough, out of predilection for 

 mechanical views, and referring to the constant revolving 

 motion, it was subsequently changed by Plato and Aristotle, 

 by a play upon words, into another derivation, aei 0eu/.( 63 ) 

 The idea of the rarity and thinness of this upper air, the 

 sether, does not appear to have been a consequence of the 



VOL. III. D 



