322 EVOLUTION OF TO-DAY. 



master the others. The migrating instinct is 

 stronger among birds than their maternal instinct, 

 for they will leave their young to perish when the 

 migrating time appears. Now if these instincts are 

 transmitted from one generation to another, it is 

 easy to understand their preservation and develop- 

 ment. Evidently those animals with instincts best 

 calculated to preserve them will be the ones to 

 survive the struggle for existence, while those which 

 have deleterious instincts will be destroyed. By 

 natural selection, therefore, those animals whose 

 strongest instincts are best calculated for the good 

 of the individual will continue to exist, while others 

 will disappear. Further, turning to the instincts of 

 man, the instincts which developing man possessed 

 will be assisted by his intelligence. He will be able 

 partially to understand the results of his customs 

 and habits. He will slowly learn to follow lines of 

 conduct which he finds best adapted for the preser- 

 vation of his life, and will, moreover, soon discover 

 what gives him the most pleasure. Such habits will 

 be repeated and handed down from generation to 

 generation, until they finally become firmly fixed in 

 the race as inherited habits or instincts. Such 

 instincts become the moral sense. 



But this is not reaching the bottom of the matter, 

 even if it be granted for a moment that such 

 instincts can become a moral sense. They would 

 make duty and pleasure the same thing, or at all 

 events would make man's duty to preserve his own 

 life his only duty. But every one realizes that many 

 acts which we feel an obligation to perform are not 



