ORGANIC EVOLUTION — MENTAL 181 



neous with the evolution of the higher portion of the 

 brain, and certainly dependent on that evolution, has 

 been an evolution of mental variability, which has still 

 further increased the correspondence. In man this 

 power of developing mentally in response to stimulation 

 from the environment has grown to be so great, and is 

 of such importance in his struggle for existence, that 

 his survival is determined mainly by virtue of it, not 

 by his inborn mental traits (instincts), which have 

 therefore undergone great retrogression. It follows 

 that nations, the individuals of which have on the 

 average large brains, which have the cerebrum and the 

 cerebellum much developed, differ from races the in- 

 dividuals of which have smaller brains, which have the 

 cerebrum and cerebellum less developed, mainly in 

 powers of varying, of developing mentally, by acquiring 

 mental traits in response to appropriate stimulation ; 

 not mainly in inborn traits, such as are implied when 

 it is said that this or that race differs inherently from 

 this or that other, in that it possesses a greater genius 

 for empire or colonization, or music, or art, &c. Indeed, 

 while it is conceivable that survival of the fittest has 

 caused the evolution of the instincts properly so called 

 (love, fear, rage, &c.), or rather, to speak more precisely, 

 of the nervous structures which subserve these instincts ; 

 and while it is conceivable that it has caused the 

 evolution of the higher portions of the brain, and, as a 

 consequence, the evolution of the power of varying 

 mentally in response to appropriate stimulation, of ac- 

 quiring fit knowledge and ways of thinking and acting 

 from the environment ; it is not conceivable that it can 

 have produced such inborn mental differences among 

 races,, as are meant when it is said that the Englishman 

 is "by nature" resolute, the Frenchman vain; the 

 Italian excitable, the German phlegmatic, the West 

 African cruel, and so forth. For it can hardly be, that 



