DEVELOPMENT BY NATURAL SELECTION. 129 



of the tables on the claims of physical science ; but no 

 one has ever found any way of escape from Hume's 

 reductio ad absurdum of these claims. 



The next great step taken was by Immanuel Kant. 

 He showed that when " sensations " or " impressions " 

 are examined they are always found to carry with them 

 relations to the unity of the percipient mind, as well 

 as to relations of time, space, and causal connection, 

 just as in what we ordinarily call the " real " world. 

 He therefore concluded that though we cannot know 

 the " things in themselves " that are behind the " im- 

 pressions," order and connection are imposed on them 

 by the percipient mind, and the physical world appears 

 to us as it does, just because the forms in which this 

 order is imposed are what they are. Kant enumerated 

 the general forms, or categories, under which the mind 

 orders its impressions. He included time and space 

 relations, and those of substance and of cause and 

 effect, but excluded final causes, including the distinctive 

 conception of life. In the realm of what Kant calls 

 the " Understanding " as distinct from Reason, and 

 what other writers, including, in recent times, Bergson, 

 call the Intellect, there is no place for such conceptions. 

 In this way Kant made his peace with the claims of 

 non-biological natural science, so that Kantians, though 

 still idealists, have been among the strongest supporters 

 of a mechanistic view of life. We must look on life as 

 mechanism, they say, just because our minds are so 

 constituted that we cannot do otherwise. 



Kant's most famous successor, Hegel, rejected the 

 " thing in itself" as an unreal shadow, and thus became 

 what is known as an " absolute idealist." For absolute 



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