72 ESSAYS OF A BIOLOGIST 



world, be present in lower organisms and in the 

 lifeless matter from which they originally sprang. 



In the present state of our knowledge, the study 

 of physics and chemistry can be pursued without 

 any reference to mental processes. But the study 

 of biology cannot : and that is one reason why 

 the centre of gravity of science as a whole is shifting 

 — it is shifting for exactly the same reason that the 

 centre of gravity of a house shifts during its construc- 

 tion — because the foundations have to be built first. 



Our second reason is as follows. Biology is once 

 more the link between root and flower, between physics 

 and chemistry and human affairs, in regard to evolution. 

 I say evolution : it would be better to broaden the 

 idea by saying the directional processes to be seen in 

 the universe. So far as a main direction is to be 

 observed in physics and chemistry, it is, as all author- 

 ities are agreed, towards the degradation of energy 

 and a final state in which not only life but all activity 

 whatsoever will be reduced to nothing, all the waters 

 of energy run down into a single dead level of move- 

 less ocean. Biology, on the other hand, presents us 

 with the spectacle of an evolution in which the main 

 direction is the raising of the maximum level of 

 certain qualities of living beings, such as efficiency 

 of organs, co-ordination, size, accuracy and range of 

 senses, capacity for knowledge, memory and educa- 

 bility, emotional intensity, — qualities which in one 

 way or another lead to a more efficient control by 



