CH. XVI.] THE EVOLUTION OF MIND. 161 



tendency toward the formation of certain special nerve- 

 connectious, individual experience tends now to assist and 

 now to clieck the inherited tendency. And so the number 

 and direction of transit-lines in any brain is due to the 

 cooperation of innumerable ancestral and individual ex- 

 periences. Locke was therefore wrong in calling the infant's 

 mind a blank sheet upon which experience is to write know- 

 ledge. The mind of the infant cannot be compared to a 

 blank sheet, but rather to a sheet already written over here 

 and there with invisible ink, which tends to show itself as 

 the chemistry of experience supplies the requisite conditions. 

 Or, dropping metaphor, the infant's mind is correlated with 

 the functions of a complex mass of nerve-tissue which 

 already has certain definite nutritive tendencies. On the 

 other hand, the school of Leibnitz and Kant was wrong in 

 assuming a kind of intuitional knowledge not ultimately 

 due to experience. For the ideas formerly called innate or 

 intuitional are the results of nutritive tendencies in the 

 cerebral tissue, which have been strengthened by the uni- 

 form experience of countless generations, until they have 

 become as resistless as the tendency of the dorsal line of 

 the embryo to develope into a vertebral column. The 

 strength of Locke's position lay in the assertion that all 

 knowledge is ultimately derived from experience, — that is, 

 from the intercourse between the organism and the environ- 

 ment. The strength of Kant's position lay in the recogni- 

 tion of the fact that the brain has definite tendencies, even 

 it birth. The Doctrine of Evolution harmonizes these two 

 seemingly-opposite views, by showing us that in learning we 

 lie merely acquiring latent capacities of reproducing ideas ; 

 vind that beneath these capacities lie more or less powerful 

 aucritive ':endencies, which are transmissible from parent to 

 child. 



I belie v^e that the last difficulties which may have hovered 

 about the doctrine of the Test of Truth, expounded iu the 



VOL. IL M 



