10 EVOLUTION AND ANIMAL LIFE 



grasp all their data. The combined effort of all men, the flower 

 of the altruism of the ages, which we call science, has made 

 only a beginning in such study. 



But, however incomplete our realization of the laws of life, 

 we may be sure that they are never broken. Each law is the 

 expression of the best possible way in which causes and results 

 can be linked. It is the necessary sequence of events, therefore 

 the best sequence, if we may imagine for a moment that the 

 human words "good' and "bad' are applicable to world 

 processes. The laws of nature are not executors of human 

 justice. Each has its own operation and no other. Each 

 represents its own tendency toward cosmic order. A law in 

 this sense cannot be "broken." "If God should wink at a 

 single act of injustice," says the Arab proverb, "the whole 

 universe would shrivel up like a cast-off snake skin." 



The laws of nature have in themselves no necessary principle 

 of progress. Their functions, each and all, may be defined as 

 cosmic order. The law of gravitation brings order in rest or 

 motion. The laws of chemical affinity bring about molecular 

 stability. Heredity repeats strength or weakness, good or ill, 

 with like indifference. The past will not let go of us ; we cannot 

 let go of the past. The law of mutual help brings the perpetua- 

 tion of weakness as well as the strength of cooperation. Even 

 the law of pity is pitiless, and the law of mercy merciless. The 

 nerves carry sensations of pleasure or pain, themselves as indif- 

 ferent as the telegraph wire, which is man's invention to serve 

 similar purposes. Some men who call themselves pessimists 

 because they cannot read good into the operations of nature 

 forget that they cannot read evil. In morals the law of compe- 

 tition no more justifies personal, official, or national selfishness 

 or brutality than the law of gravitation justifies the shooting 

 of a bird. 



The science of bionomics centers about the theory of descent, 

 the belief that organs and species as we know them are derived 

 from other and often simpler forms by processes of divergence 

 and adaptation. According to this theory all forms of life 

 now existing, or that have existed on the earth, have risen from 

 other forms of life w r hich have previously lived in turn. All 

 characters and attributes of species and groups have developed 

 with changing conditions of life. The homologies among 

 animals are the results of common descent. The differences 



