30 WHAT 18 LIFE 



Sometimes a long period of time intervenes be- 

 tween a speculation and its proof or refutation; 

 and that which amounts to a proof of the correct- 

 ness of the interpretation may be secured without 

 the slightest reference to the speculation of long ago. 

 This happened in the case of the atomic theory of 

 electricity. Thales of Miletus, ca. 600 B. C, specu- 

 lated on the discrete nature of electricity. Twenty- 

 five hundred years later (1909) Robert Andrews 

 Millikan isolated and measured the electron. Yet 

 hardly for a moment could one suppose that the re- 

 search work of Millikan, the epoch-making work of 

 J. J. Thomson, and the efforts of Townsend, C. T. R. 

 Wilson, H. A. Wilson, William Crookes, and of 

 Pluecker and Hittorf, were inspired by the specu- 

 lation of Thales. But that electricity is atomic is 

 no longer a speculation, a hypothesis, or a theory, 

 but an established fact. 



It is plain, then, that a hypothesis or a theory is a 

 thing of merely temporary existence, and that proof 

 converts speculation into knowledge, and theory into 

 accepted fact. 



"The requisite standard of proof" has been raised 

 in all departments of learning. Today, at least so far 

 as recognized authorities are concerned, it is satis- 

 factorily high: Everywhere there is insistence upon 

 methods that can supply evidence in place of mere 



