62 THE ADVANCE OF SCIENCE 



the earth's history. It seems safe to 

 prophesy that the hypothesis of the evo- 

 lution 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 founda- 

 tion. 

 The old It may perhaps occur to the reader 



new that the boasted progress of physical sci- 

 theOTy. ence does not come to much, if our pres- 

 ent conceptions of the fundamental nature 

 of matter are expressible in terms em- 

 ployed, more than two thousand years 

 ago, by the old 'master of those that 

 know.' Such a criticism, however, would 

 involve forgetfulness of the fact, that the 

 I connotation of these terms, in the mind of 

 the modern, is almost infinitely 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, 



