102 ESSAYS OF A BIOLOGIST 



Other hand, physico-chemical concepts — or at least 

 our present ones — are not all-sufficient. In the 

 first place, the very complicated arrangement of mat- 

 ter which is found in living substance has not been 

 yet sufficiently analysed by physics and chemistry: 

 accordingly we find many processes occurring in bi- 

 ology — such as the directional changes in evolution 

 of which we have spoken — which could not have been 

 foretold on our present physico-chemical knowledge, 

 but must be investigated separately as adding to our 

 store of facts and principles, in the confident hope 

 that a synthesis will one day be possible. Secondly, 

 a whole new category of phenomena, the psycholog- 

 ical, is first met with in biology, and to this we cannot 

 as yet apply physical or chemical ideas at all. 



For a combination of these two reasons, biology 

 deals with certain concepts which are not implicit in 

 current physico-chemical ideas. Physics and chem- 

 istry are basic for biology, but they are not 

 exhaustive. 



In a very similar way, biology is basic for sociol- 

 ogy, but again not exhaustive. Certain limits are set 

 to human life through man's organic nature. Cer- 

 tain of his activities can be completely analysed in 

 terms of biology. But other of his activities, espe- 

 cially those concerned with his new type of mental 

 organization, find no counterpart in the rest of the 

 biological kingdoms, and must be studied in and for 

 themselves. 



Bergson would have us believe that evolution is 



