Custom 



deeply fixed in the race. Another group saved 

 its life by taking to grazing. Grass is poor food ; 

 but it was the only chance this group had, and 

 in time it got so accustomed to eating grass that 

 it could not imagine any other form of diet, and at 

 first would refuse even oysters when placed in 

 its way 1 Another group saw an opening in trees ; 

 it developed a long neck and became the giraffe. 

 But the fact that the giraffe lives on leaves, and 

 the sheep on grass, and the wolf on animal matter, 

 and that custom is in each so strong that at first 

 the creature will refuse any other kind of diet, 

 does not of itself prove that that diet is the best 

 or most physiologically suitable for it. In other 

 words, it is an assumption to suppose that " adap- 

 tation to environment " is the sole or even the 

 main factor in the constitution of well-marked 

 varieties or genera ; for this is to neglect (among 

 other things) the force of mere use or wont, which 

 has about the same import in race-growth that 

 momentum has in dynamics ; and causes the race, 

 once started in any direction, to maintain its line 

 of movement — and often in despite of its environ- 

 ment — even for thousands of years. 



Returning to man we see him enveloped in a 

 myriad customs — local customs, class customs, 

 race customs, family customs, religious customs ; 

 customs in food, customs in clothing, customs in 

 furniture, form of habitation, industrial production, 

 art, social and municipal and national life, etc. ; 

 and the question arises. Where is the grain of 

 necessity which underlies it all ? How much 



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