46 Heredity and Social Progress 



row their food or activities and thus bring on 

 an arbitrary elimination that does not make 

 for progress. A stationary condition results, 

 and a type is formed that in animals becomes 

 a fixed species. 



In the creation of a species, two forces are 

 needed: one that shall involve the principle of 

 variation and cause animals to break out of 

 their restraints and to adjust themselves to 

 new conditions ; and at the same time a second 

 is needed which cuts off further change and 

 drives them back toward their primitive con- 

 dition. Progress is due to surplus energy ; 

 retrogression or an arrest of development 

 comes from emotions. These two forces ac- 

 count for the changes through which organ- 

 isms go, and as they act more quickly than 

 natural selection, they are more likely than it 

 is to be the actual causes of organic changes. 



In saying that emotions are defensive, sym- 

 pathetic, and the cause of arrested develop- 

 ment, I seem to have overlooked one important 

 class, the sexual emotions. They are pleasur- 

 able and do not come from adverse elements 

 in the environment. Although this may be 



