42 Darwinism and Deity. 



The law of electricity explains the order and suc- 

 cession of electrical phenomena. Electrical phenomena 

 are produced by a natural force called electricity. What 

 is that natural force? 



Physical science concerns itself only with phenomena 

 and their order of succession. If we ask what is the 

 nature of the force which produces phenomena, it has 

 no answer. 



This can be illustrated farther, by taking a single 

 force of nature; for example, the attraction of gravita- 

 tion. I remember when in college, Prof. Pierce, the 

 chief of American mathematicians, after going over on 

 the blackboard a demonstration of the theory of uni- 

 versal gravitation, turned to the class, and said : " Here, 

 gentlemen, is a demonstration of that law. We have 

 proved that every particle of matter tends toward every 

 other particle of matter in inverse proportion to the 

 square of the distance, etc. If you ask what makes them 

 so tend, this department has no answer; you must take 

 that question to another department of the university." 



Newton had already said substantially the same 

 thing. At the close of the Principia he savs: "Hith- 

 erto, I have not been able to deduce the cause of those 

 properties from phenomena, and I frame no hypothesis; 

 for whatever is deduced from phenomena, is to be called 

 an hypothesis, and hypotheses, whether metaphysical or 

 physical, whether of occult qualities or mechanical, 

 have no place in experimental philosophy. To us, it 

 is enough that gravity does really exist and act accord- 

 ing to the rules which we have explained." 



If experimental philosophy will not tell us what is 

 this force that we call gravity or attraction of gravita- 



