44 The Direction of Evolution 



social evolution or development, follow such a law — that 

 they follow, moreover, a very different and in no wise anal- 

 osfous law. The o:reater the variation in tradition, — the idea 

 of the genius, the protest of a reformer, the new formula- 

 tion of a scientific truth, — the greater may be its effect ; 

 while, by the law of biological regression, the great varia- 

 tion, the sport, tends to be swamped by interbreeding, and 

 the wider his departure from the mean the less his chance 

 of impressing his characters upon posterity. The whole 

 case is summed up in the statement made above, to the 

 effect that social progress is no longer under the limitations 

 set by physical heredity ; it is under the laws of mental 

 process and organization.^ 



Some one may say, what is indeed quite true,^ that this 

 progress is after all due to the operation of natural selec- 

 tion, whereby the necessary plasticity required for the 

 mind was selected and fixed ; but such a statement alone 

 would be quite inadequate as an explanation. For when 

 so much is said, what is gained t So far may we go in 

 the interpretation from the side of the physical ; but the 

 meaning, I submit, of evolution in this direction is not to 

 be found on the side of plasticity but on the side of mind 

 — the accommodations which are effected on the basis of 

 the plasticity. We now, in short, recognize that wonder- 

 ful endowment which is correlated with plasticity in the 

 psychophysical whole. The emphasis in the interpreta- 

 tion of the twofold fact is not upon the process of the 

 physical, but upon the events which are taking place in 



1 See the remarks on history, and especially the criticism of Professor Karl 

 Pearson, in Chap. XIX. § 7. 



2 Professor Osborn, however, one of the original advocates of organic selec- 

 tion, does not admit that plasticity has been acquired through natural selec- 

 tion ; sec the American Naturalist, Nov. 1897, cited in Appendix A. 



