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Terse ; that by the energy of this ethereal substance, 

 to which they gave the name of ether, all the parts 

 of nature were produced, sustained, preserved, and 

 linked together : for it embraced every thing, and in 

 it the celestial bodies performed their revolutions. 



3. Aristotle, explaining Pythagoras's opinion of 

 ether,ascribes the same also to Anaxagoras, saying, that 

 he looked upon the most remote spaces of the universe, 

 as filled with a substance, called ether by the philoso- 

 phers of his time, but which he himself understood (o 

 be a subtle and active fire. And Aristotle himself, in 

 another place, understands by ether, a * fifth element 

 pure and unalterable, of an active and vital nature, 

 but entirely different from air and fire. 1 



4. Pythagoras, according to Diogenes Laerfius, and 

 Hierocles. affirmed, that the air which invests our 

 earth, is impure and mixed ; but that the air which is 

 above, is pure, healthful, and ail of a piece. lie calls 

 it * free- ether, emancipated from all gross matter, a 

 celestial substance that penetrated at w r ill the pores of 

 all bodies ;' just like that of the Newtonians, which 

 fills all space, without giving auy obstruction to the 

 stars in their courses. And Empedocfes one of the 

 most celebrated disciples of Pythagoras, is quoted by 

 Plutarch, and St. Clemens A lexandrinus, as admitting 

 an ethereal substance, which -filled all space, and con- 

 tained in it all the bodies of the universe. Likewise 

 Plato, speaking of air, distinguishes it into two kinds, 

 the one gross and tilled with vapours, which is what 

 we breathe ; * the other more refined railed ethtT, in 

 which the celestial bodies are immerged and where 

 they roll,' 



5. The nature of air was riajcfs known among the 

 ancients, than that of ether. They regard it as a 

 general menstruum, containing all the volatile parts of 

 every thing in nature, which being variously agitated, 

 and ditierently combined in its embrace, produced al.! 



