THE PATH OF EVOLUTION 



light and electricity are modes of motion only, and 

 the accurate knowledge we now have of the laws 

 governing the phenomena presented, in their trans- 

 mission and conversion into other forms of physical 

 and chemical energy, constitute the greatest and most 

 important part of the foundations of modern science. 

 The theories of light, heat and electricity now claim 

 almost without dispute the existence of the ether fill- 

 ing interstellar space as the postulate of their being, 

 since they are but the vibrations or the undulations 

 thereof, and without which, they are not. 



The nature of the Ether and its constitution has 

 been the object of thought of men from the earliest 

 historic times. About 500 B. C. Xenophanes and 

 the Eleatic School believed in the immutability, the 

 unity, the continuity and the immobility of matter, 

 and that the evidences of the senses were illusions 

 only. Leucippe, in opposition thereto, taught that 

 matter was like a sponge, in which the atoms are 

 separated by vacous spaces, the atoms being solid, 

 impenetrable and almost infinitely small. All bodies 

 are composed of this assemblage, or union, of the 

 plenum and the vacuum. The atoms are of various 

 shapes, and when grouped in various ways give rise 

 to the different kinds of matter. His disciple, Democ- 

 ritus (470 B. C.), taught what is now nearly the ac- 



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