30 ESSAYS OF 'A BIOLOGIST 



simple degrees of memory; then associative memory, 

 as in birds and mammals, for whom most reactions 

 are not given in the inherited constitution, but must 

 be learnt; then rational memory, in which the power 

 of generalization liberates life from blind dependence 

 upon the local and the accidental; and finally tradi- 

 tion, whereby the amount of experience available to 

 the developing race is not constituted merely by the 

 isolated and limited experiences of its members, but 

 by their sum. More and more of the past becomes 

 directly operative in the present; further and further 

 into the future can the aim of the present extend. 



Finally we can conclude with a high degree of cer- 

 tainty that the psychical faculties — of knowing, feel- 

 ing, and willing — have increased in intensity, and 

 also in their relative importance for the life of the 

 individual organism. 



We have condensed our summary into these six 

 general statements; if we wish to reach a still more 

 general form, the most general form possible, we can 

 redistil it thus: During the course of evolution in 

 time, there has been an increase in the control exerted 

 by organisms over their environment, and in their 

 independence with regard to it; there has been an in- 

 crease in the harmony of the parts of organisms; and 

 there has been an increase in the psychical powers 

 of organisms, an increase of willing, of feeling, and 

 of knowing. 



This increase has not been universal; many organ- 

 isms have remained stationary or have even re- 



