DOCTKINE OF THE ANCIENTS. 



repulsion,) by virtue of which the celestial bodies 

 were preserved in their respective courses, and 

 connected as by an invisible everlasting chain ; 

 and without which there could be no generation 

 or dissolution of bodies, 



Such were the opinions of Pythagoras, Par- 

 menides, Democritus, Heraclitus, Plato, and 

 many others. Hippocrates termed it " a strong 

 but invisible fire which rules all things without 

 noise, and is never in repose; which actuates 

 and animates the whole system of nature." 

 Here is a definition of heat in accordance with 

 the discoveries of Dr. Black, but still more com- 

 prehensive and important. 



Like the ancient Greek philosophers, Bacon 

 reduced all matter to two classes, active and 

 passive ; the first of which he describes as rare, 

 invisible, and without weight, though a real and 

 quantitative substance, pervading and filling the 

 pores of all gross bodies. I have already shown 

 that this active spirit, to which Bacon referred 

 all the motions and transformations of matter, is 

 only another name for caloric. (See page 24.) 

 But if this pneumatical power be the cause of all 

 the changes of living and dead matter, it must 

 be the cause of attraction, as well as repulsion ; 

 of decomposition and recombination. 



In his treatise on the Wisdom of the Ancients, 

 Bacon further maintains that the attraction of 

 matter was typified among the early Greek phi- 



M 



