IMMUTABILITY OF SPECIES. 83 



tual power, and do not result from the immediate action 

 of physical causes. 



So far, then, from disclosing the effects of physical 

 agents, whatever changes are known to take place in the 

 course of time among organized beings appear as the 

 result of an intellectual power, and go therefore to sub- 

 stantiate the view, that all the differences observed among 

 finite beings are ordained by the action of the Supreme 

 Intellect, and not determined by physical causes. This 

 position is still more strengthened, when Ave consider that 

 the differences which exist between different races of do- 

 mesticated animals and the varieties of our cultivated 

 plants, as well as among the races of men, are permanent 

 under the most diversified climatic influence ; a fact 

 which is daily proved more conclusively by the extensive 

 migrations of the civilized nations, and which stands in 

 direct contradiction to the supposition that such or similar 

 influences could have produced them. 



When considering the subject of domestication, in par- 

 ticular, it ought further to lie remembered, that every 

 race of man has its own peculiar kinds of domesticated 

 animals and of cultivated plants, and that these exhibit 

 much fewer varieties among themselves in the case of 

 those races which have had little or no intercourse with 

 other races, than in the case of those nations which have 

 been formed by the mixture of several tribes. 



It is often stated, that the ancient philosophers have 

 solved satisfactorily all the great questions interesting to 

 man ; and that modern investigations, though they have 

 grasped with new vigour, and illuminated with new light, 

 all the phenomena of the material world, have added little 

 or nothing in the field of intellectual progress. Is this 

 true ? There is no question so deeply interesting to man 



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