144 Brain : 



left the rank of his brutal mammalian congeners and be- 

 gan to use his brain. As a result, his brain grew and has 

 entered upon an era of development the limits of which 

 no one can foresee. In consequence we find this tissue to 

 be still progressive, but associated in the organism with a 

 score of other unprogressive tissues which tend but to pass 

 through a fixed cycle of growth and decline. It is this 

 condition which affords the key-note and the explanation 

 to his strange creeds, aspirations, superstitions, hopes, and 

 fears; his optimisms and his pessimisms; his gods, his 

 christs, and his satans. 



And this is that riddle of the Sphinx, that fateful inter- 

 rogation of the Ages which he has to answer : Will the 

 progressive, still developing brain acquire such knowledge 

 and obtain such mastery and such control over the forces 

 of nature as to " redeem," regenerate, and renew at will 

 the other unprogressive tissues with which brain is yoked 

 in the organism, and which at present condemn it to a 

 brief lifetime with them ? Can the progressive tissue re- 

 deem and save the unprogressive tissues ? We have now 

 good hopes that it can. 



