EVOLUTION AND THE HIGHER HUMAN LIFE 287 



of duty that elderly people would voluntarily go to a 

 living grave surrounded by their friends ; while in other 

 authentic cases, parents have first killed their sons who 

 failed to obey the tribal law, and have then committed 

 suicide. We can see how nature and necessity would 

 institute a law requiring such conduct where a tribe must 

 carry on almost incessant warfare and where the avail- 

 able food supplies would be enough for only the most 

 efficient individuals. Infanticide also has been prac- 

 tised for reasons of biological utility, as among the 

 Romans, who at first maintained their racial vigor by 

 deliberately ordering the death of weak babes. But times 

 have changed, and ethics has become very different 

 with passing decades. Our civilization has resulted in 

 a development of human sympathy as an emotional out- 

 growth of necessary altruism ; this motive directs us 

 through charitable institutions and hospitals to prolong 

 countless lives which are more or less inefficient, but 

 which do not render the whole body politic incompe- 

 tent in its struggle for existence. 



Nature then has itself attended to the development 

 and institution of ethics. As we look back over the 

 long series of stages leading to our own system of con- 

 duct the most striking feature of the history is the in- 

 creasing power of self-control or inhibition. As a natu- 

 ral instinct this tends to prevent the committing of acts 

 which for one reason or another are naturally harmful to 

 society as a whole. What we call conscience is an in- 

 stinct implanted by purely natural factors, and it un- 

 consciously turns the course of human action in the 

 directions of selfish and altruistic interests. Conscience, 

 then, without ceasing to have validity and efficiency, ap- 



