NATURAL SELECTION 131 



4. Since the process of elimination must go on, is it The struggle 

 perfectly haphazard ? Is the lottery altogether im- 



partial? Surely not; we have only to think for a vivaiofthe 

 moment of the causes of premature death. Disease 

 may not spare the best, from our point of view, but it 

 picks and chooses in its own manner. Some deaths are 

 due to what we call "pure accident," but the more we 

 examine into the subject the smaller this accidental 

 group appears to become. Creatures attacked by 

 enemies may fight or fly, but they differ in their ability 

 to do either. Individuals are not exactly alike, and 

 consequently their chances of survival are not alike. 

 After all, it is not Nature which chooses, if by " Nature" 

 we mean an external, impersonal agency. Nature would 

 be impartial, if the behavior of life were uniform. The 

 process we have just described, which is going on every- 

 where and at all times, is what Darwin called Natural 

 Selection. Its consequence is the Survival of the Fittest. 

 The effort to survive is spoken of as the Struggle for 

 Existence. These expressions are now classical, and 

 cannot be changed ; but they need a little explanation. 

 The struggle for existence appears to imply volition, but 

 this is not intended. There is volition in the effort to 

 obtain food, or to fight enemies ; but the defense of the 

 body against the attacks of bacteria is quite uncon- 

 scious. Plants, which we do not think of as being 

 aware of things, struggle for existence as much as ani- 

 mals. Then, again, the survival of the fittest implies 

 only fitness to survive under the given conditions. Ideal 

 fitness has nothing to do with it. One who is fit to go 

 through college may not be fit to resist smallpox or 

 swim when thrown into the water. Moreover, the only 

 fitness we are concerned with is that to produce off- 

 spring. Creatures may live to old age, yet remain 



