in THE MEANING OF EVOLUTION 265 



be cleared up and completed. We will distinguish 

 more sharply what is accidental from what is essential 

 in this evolution. 



The impetus of life, of which we are speaking, 

 consists in a need of creation. It cannot create 

 absolutely, because it is confronted with matter, that is 

 to say with the movement that is the inverse of its 

 own. But it seizes upon this matter, which is necessity 

 itself, and strives to introduce into it the largest possible 

 amount of indetermination and liberty. How does it 

 go to work ? 



An animal high in the scale may be represented in 

 a general way, we said, as a sensori-motor nervous 

 system imposed on digestive, respiratory, circulatory 

 systems, etc. The function of these latter is to cleanse, 

 repair and protect the nervous system, to make it as 

 independent as possible of external circumstances, but, 

 above all, to furnish it with energy to be expended in 

 movements. The increasing complexity of the organism 

 is therefore due theoretically (in spite of innumerable 

 exceptions due to accidents of evolution) to the 

 necessity of complexity in the nervous system. No 

 doubt, each complication of any part of the organism 

 involves many others in addition, because this part 

 itself must live, and every change in one point of 

 the body reverberates, as it were, throughout. The 

 complication may therefore go on to infinity in all 

 directions ; but it is the complication of the nervous 

 system which conditions the others in right, if not 

 always in fact. Now, in what does the progress of the 

 nervous system itself consist ? In a simultaneous 

 development of automatic activity and of voluntary 

 activity, the first furnishing the second with an appro 

 priate instrument. Thus, in an organism such as ours, 



