THE PATH OF EVOLUTION 



Fire itself is composed of round atoms, always in 

 agitation." * 



Epicurus (342-270 B. c.) adopted Democritus' 

 idea of the atoms, to which he added the properties 

 of weight, thus constituting gravitation and affinity, 

 which constitutes the germ of Chemistry. It is the 

 philosophy of Epicurus that Lucretius expounds in 

 his poem " De Rerum Natura," much of which reads 

 almost like a modern treatise on Physics. Lucretius 

 argues that space must consist of atoms of material 

 substance, separated one from another by vacuous in- 

 tervals. He insists elsewhere that they must also be 

 in constant motion. These are conditions that the 

 modern atomic theory of the Ether likewise requires. 

 He writes : " Thus if there was no such thing as space 

 vacated, or a vacuum, everything would be solid ; 

 then, again, unless there were some things solid to 

 fill up the space, everything, all, would be empty 

 space. Body from space is in itself distinct, for all 

 is neither full nor is all void, and thus there are 

 solid atoms which cause the difference between the 

 plenum and space. These solid atoms by no force 

 from without can be dissolved, nor can they be de- 

 stroyed by being penetrated from within, nor made to 

 yield by any other means, as I have taken pains to 

 show. For no things can come in collision or be 



" Democrite" par Etienne Pariset. Biog. Univ. T. 10, p. 387. 

 122 



