Theories of Electricity 157 



We recognize that Franklin possessed unusual clear- 

 ness of physical insight, but we must refrain for that 

 reason from endowing him with the uncanny gift of 

 prophetic vision. 



With regard to the question " What is electricity?" 

 so often asked the scientist by the layman, science cannot 

 at present venture an adequate answer. Nor is this sur- 

 prising when we consider what a fundamental part elec- 

 tricity plays in nature. We have seen that electricity 

 is a constituent of all matter, and, indeed, that what we 

 call matter is electricity in motion. Attempts have been 

 made to explain electricity as a manifestation of the uni- 

 versal medium or ether, but until we know more of the 

 properties of the ether, such theories must of necessity 

 lack physical definiteness. Even if we may ultimately 

 explain electricity in terms of the ether, there remains 

 the still more fundamental problem, " What is the 

 ether?" An attempt to explain such fundamental con- 

 ceptions seems of necessity to end in metaphysical sub- 

 tilties. 



