368 The Morality of Nature 



ducive to greater speed or endurance. It appears necessary 

 to allow long periods of continued variation to establish any 

 such form as is entitled to be called new. 



The question of the cause of variation may be passed with 

 brief mention, as not essential to the present study. The 

 moral aspect of evolution depends upon the fact that varia- 

 tions appear, and are added to the heredity, and so consti- 

 tute a possibility of upward progress as a consequence of 

 right conduct ; this is a fact which can be established without 

 discovery of the source of variation. 



