42 CHANGE 



progress. Between it and habit there is constant 

 antagonism, and a slight preponderance of one or 

 the other marks the difference between the 

 Liberal and the Conservative temperament. The 

 manifestations of this instinct can be traced 

 throughout the animal kingdom : it is the impulse 

 which prompts so many creatures to change their 

 homes to migrate. The force of habit makes 

 strongly for stay-at-home life ; yet at certain 

 periods, or in certain circumstances, many kinds 

 of animals are seized with a passion to adventure 

 themselves in new surroundings. Swallows and 

 snipe, for instance, are annually driven by this 

 impulse enormous distances across ice-bound 

 mountains and stormy seas. In most cases the 

 impulse has results of advantage : stirred by it, 

 birds avail themselves of food which abounds 

 during summer in northern, and during winter 

 in southern latitudes. Those which feed upon 

 insects would perish during the lifelessness of a 

 northern winter. But the instinct is sometimes a 

 deadly possession. Swarms of locusts and butter- 

 flies will fly out to certain death in the ocean. 

 The lemmings 1 of Norway periodically assemble 

 in vast multitudes and travel westwards with no 

 apparent object, those that escape death on the 

 mountains not fearing it when they reach the 

 coast, but swimming boldly out to sea. In the 

 history of mankind the migratory impulse has 

 been of incalculable importance : it has provoked 

 desolating wars ; but it has maintained a con- 

 nection between different peoples, and has been a 

 potent influence in spreading culture. Without 

 it races would have lived, as it were, in closed 

 compartments, and we should not find that the 

 primary discoveries of civilization the use of 

 fire, of the plough, of the loom, as well as many 



1 A small field rat (Myodes lemmus). 



