124 EVOLUTION AND MAN S PLACE IN NATURE 



we contemplate organic sensibility. This is more 

 widely distributed, and it came earliest. If any one 

 take sensibility as equivalent to mind/ the form of 

 the problem is changed; the difficulties as to the 

 appearance of rational poAver continue as before. 



If we are to escape play upon words, we must come 

 to sharp distinctions between sensibility and ration 

 ality. Familiar facts show a marked severance 

 between the lower forms of life and the higher 

 mammals, and a still wider distinction between 

 simpler organisms and the human species. If 

 only we make sure that we start our inquiry 

 with a function common to all life, there will follow 

 obvious advantages if we contrast that with such 

 mental characteristics as are common to men. In 

 following this course, full account must be made of 

 the continuity of structure and function already 

 recognised. A man is sensitive to contact as a 

 mollusc is, and just as a monkey is. Nerve fibre, 

 nerve cell, and brain, are severally homologous 

 in structure and functions. Thus far, we deny 

 nothing to the lowest organism which we claim for 

 man. Sensitiveness in the organism, succession of 

 sensory impressions in the history of the life, and 

 correlation of these with activity through the nerve 

 centres, are characteristics of all organic life, including 

 that of the insect with that of the man. 



What, then, is it which is peculiar to man ? Jt is 

 his rational discrimination, in advance of sensory 

 discrimination. All organism feels contact ancfacts 

 in response to it. All human life not only does 

 these two things, but also interprets experience, 

 thereby forming a knowledge of the things with 



