ORGANIC EVOLUTION — MENTAL 177 



himself to an environment of vastly greater complexity. 

 By means of written symbols, representing words or 

 thoughts, he is not only able to store in a form easily 

 available to himself, his fellows, and his descendants ac- 

 cumulations of knowledge so immense that no memory 

 could contain them, but by means of these symbols he is 

 able (e. g. in the mathematics) to perform feats of think- 

 ing utterly beyond the powers of the unaided mind ; just 

 as by means of tools, machinery, and other mechanical 

 contrivances he is able to perform physical feats utterly 

 beyond the unaided powers of his body. To written 

 symbols representing words or thoughts is due, prac- 

 tically speaking, his whole advance beyond the savage 

 in the past, and to them are due also his vast potenti- 

 alities for future advance. 



