The History of Things 77 



tation or electricity is irreducible, it is illegitimate. 

 It is faint-hearted and premature to assume that 

 what is at present irreducible will remain irreduci- 

 ble, unless some good reason can be given for so 

 judging. It yields no permanent satisfaction when 

 we reflect on the past, when we consider the suc- 

 cess which has attended scientific efforts to reduce 

 the number of supposed separate entities or pow- 

 ers. The use of "William of Occam's razor" 

 Entia non sunt midtiplicanda prater necessi- 

 tatem has already had its reward. It has given 

 us a deeper conviction of the "oneness " of Nature. 

 We need simply recall how "Caloric" was elim- 

 inated, yielding to the modern interpretation of 

 heat "as a mode of motion"; how emanations of 

 "Light" had to follow, when the undulatory or 

 the electro-magnetic theory of their nature was 

 established; how "Force" itself has become a 

 mere measure of motion; and how even "Matter" 

 tends to be resolved into units of negative elec- 

 tricity, carrying with them a bound portion of the 

 ether in which they are bathed. By all means, let 

 us have a criticism of the categories of science 

 which is indeed part of the business of a useful 

 philosophy but let us avoid the dogmatism of 

 asserting that the scientific unification of nature 

 has reached its limits. "God said, 'Let Newton 

 be,' and there was light," and another Newton may 

 be born to-morrow. 



