372 FRAGMENTS OF SCIENCE 



centre of the nervous system. But how did it originate 

 there? This is the critical question, to which some will 

 reply that it had its origin in the human soul. 



The aim and effort of science is to explain the un- 

 known in terms of the known. Explanation, therefore, 

 is conditioned by knowledge. You have probably heard 

 the story of the German peasant, who, in early railway 

 days, was taken to see the performance of a locomotive. 

 He had never known carriages to be moved except by 

 animal power. Every explanation outside of this concep- 

 tion lay beyond his experience, and could not be invoked. 

 After long reflection therefore, and seeing no possible 

 escape from the conclusion, he exclaimed confidently to 

 his companion, "Es mtlssen doch Pferde darin sein" — 

 There must be horses inside. Amusing as this locomo- 

 tive theory may seem, it illustrates a deep-lying truth. 



With reference to our present question, some may be 

 disposed to press upon me such considerations as these: 

 Your motor nerves are so many speaking-tubes, through 

 which messages are sent from the man to the world; and 

 your sensor nerves are so many conduits through which 

 the whispers of the world are sent back to the man. But 

 you have not told us where is the man. Who or what 

 is it that sends and receives those messages through the 

 bodily organism? Do not the phenomena point to the 

 existence of a self within the self, which acts through 

 the body as through a skilfully constructed instrument? 

 You picture the muscles as hearkening to the commands 

 sent through the motor nerves, and you picture the sensor 

 nerves as the vehicles of incoming intelligence; are you 

 not bound to supplement this mechanism by the assump- 

 tion of an entity which uses it? In other words, are you 



