38 The Universe and Life 



changes bring about mental changes shows that the 

 physical and mental are not independent. The physi- 

 cal does affect the mental. But is it also true that the 

 mental affects the physical ; that thoughts and pur- 

 poses and knowledge affect behavior.? Or is there 

 reason to suppose that the relation is all in one direc- 

 tion ; that physical things affect mental experiences, 

 but mental experiences do not affect physical things ? 



This is for science exclusively a question for ex- 

 perience and experimentation. Every day experience 

 and laboratory experimentation agree in showing 

 that different actions do occur, following upon differ- 

 ent sensations, emotions, and opinions. If I purpose 

 to eat my dinner, my action is different from that 

 which follows upon a purpose to write a letter. If, in 

 my opinion. Hoover was a better man for President 

 than Roosevelt, my vote was different from what it 

 would have been if I had held the reverse opinion. If 

 spinach has a disagreeable taste to me, I decline to 

 eat it. No one doubts that action is in fact different, 

 following upon diverse mental states, different sensa- 

 tions, feelings, purposes, opinions. 



The direct natural conclusion from this is the one 

 that is drawn in everyday life, namely, that these 

 things do affect action. The natural man supposes 

 that different sensations, different purposes, differ- 

 ent opinions, result in different actions ; that a change 

 of purpose or of opinion brings about a change of 

 action. He supposes that a man of knowledge has, 

 through his knowledge, an advantage in action over 

 an ignorant man. He supposes that a sensation of 



