80 THE PROGRESS OF SCIENcK n 



prophesy that the hypothesis of the evolution of the 

 elements from a primitive matter will, in future, 

 play no less a part in the history of science 

 than the atomic hypothesis, which, to begin 

 with, had no greater, if so great, an empirical 

 foundation. 



It may perhaps occur to the reader that the 

 boasted progress of physical science does not 

 come to much, if our present conceptions of the 

 fundamental nature of matter are expressible in 

 terms employed, more than two thousand years 

 ago, by the old " master of those that know." 

 Such a criticism, however, would involve forgetful- 

 ness of the fact, that the connotation of these 

 terms, in the mind of the modern, is almost in- 

 finitely different from that which they possessed 

 in the mind of the ancient philosopher. In 

 antiquity, they meant little more than vague 

 speculation; at the present day, they indicate 

 definite physical conceptions, susceptible of mathe- 

 matical treatment, and giving rise to innumerable 

 'Inductions, the value of which can be experimen- 

 tally tested. The old notions produced little more 

 tlian floods of dialectics; the new are powerful i 

 aids towards the increase of solid knowledge. 



Kvi-ryday observation shows that, of the 

 which compose the material world, some are 

 motion and some are, or appear to be, at rest. Of 

 the bodies in motion, some, like the sun and stars,! 



