IS THE BODY A MACHINE? 49 



The Living Body is a Machine. Reviewing the 

 subject up to this point, what must be our verdict 

 as to our ability to understand the running of the 

 living machine? In the first place, we are jus- 

 tified in regarding the body as a machine, since, 

 so far as concerns its relations to energy, it is sim- 

 ply a piece of mechanism complicated, indeed, 

 beyond any other machine, but still a machine for 

 changing one kind of energy into another. It 

 receives the energy in the form of chemical com- 

 position and converts it into heat, motion, nervous 

 wave motion, etc. All of this is sure enough. 

 Whether other forms of nervous and mental ac- 

 tivity can be placed under the same category, or 

 whether these must be regarded as belonging to 

 a realm by themselves and outside of the scope 

 of energy in the physical sense, can not perhaps 

 be yet definitely decided. We can simply say 

 that as yet no one has been able even to conceive 

 how thought can be commensurate with physical 

 energy. The utter unlikeness of thought and 

 wave motion of any kind leads us at present to 

 feel that on the side of mentality the comparison 

 of the body with a machine fails of being com- 

 plete. 



In regard to the second half of the question, 

 whether natural forces are adequate to explain 

 the running of the machine, we have again been 

 able to reach a satisfactory positive answer. Di- 

 gestion, assimilation, circulation, respiration, ex- 

 cretion, the principal categories of physiological 

 action, and at least certain phases of the action 

 of the nervous system are readily understood as 

 controlled by the action of chemical and physical 

 forces. In the accomplishment of these actions 

 there is no need for the supposition of any force 



