2 BIOLOGY AND SOCIAL PROBLEMS 



These traits seem to us to indicate the real in- 

 dividual more truly than such obvious physi- 

 cal peculiarities as stature, color of hair, and 

 the like, for the reason probably that expe- 

 rience has taught us that, though the physi- 

 cal traits may change with time, the others 

 remain relatively stable and may be counted 

 upon as more or less permanently present. 

 We group these relatively stable traits under 

 the head of personality, and we think of 

 these collectively as constituting the core and 

 essence of the individual, the real and effec- 

 tive part under cover of the more obviously 

 physical, the ego or soul of the situation. It 

 is the possession of a centralized nature, of 

 an active personality, that makes each normal 

 human being an effective and responsible unit 

 in society. His attitudes are the result of this 

 possession ; his acts are determined by it ; it is 

 in fact his inmost self. 



What can be said about personality so far 

 as its natural history is concerned? How is it, 

 for instance, related to the body? Many of the 

 ancients believed personality to permeate more 

 or less completely the whole human frame ; it 

 was a shade or shadow that simulated the form 

 of the material body in all its details, but was 



