PSYCHIC ADAPTATION 99 



in order to follow the parallelism with the 

 external series. 



But this is not all ; there remains still the improve- 

 ment of the substance of the histo-chemical 

 composition, not only of the nervous cells, but of 

 all the elements that contribute to good cerebral 

 architecture ; healthy, sound histo-chemical com- 

 position augments the precision and virtue of the 

 cerebral energies. And such a constant perfecti- 

 bility gives an idea of a future that appears like a 

 dream, since man will attain in science, in art, and 

 all applied studies a prodigious progress compared 

 with the social state of the present time. 



When the facts relating to the descent of the 

 nervous system are known, it is useless to discuss 

 this or that mode of demonstration : there is but 

 one, that which secures the greatest adaptation of 

 the intelligence to natural phenomena ; this method 

 being founded on observation and experiment. 

 There can be no other ; firstly, because this is 

 obtained from a knowledge of psychic evolution, 

 from the first animal to man ; secondly, because it 

 aims at the adaptation of the intelligence to Nature. 

 It is the only means of progress, the only road that 

 leads to the truth. 



Furthermore, in order to appreciate the great 

 light that is shed from a knowledge of the structure 

 of the human brain, and to interpret history posi- 



