228 SECRETS OF ANIMAL LIFE 
in terms of the highest values. Ass to the question 
whether the factors operative in ordinary organic 
evolution are more than complications or com- 
positions of factors which operate in inorganic 
genesis, we would answer, Much more. For Natural 
Selection operates on what is not accounted for 
mechanically, and the sifting process itself is more 
than mechanical. For the explicit organism can 
often be seen to play the new cards which the 
implicit organism has put into its hands. Organ- 
isms are at times selected by their environment; 
at other times they select it. They often help 
to make their own sieves. All our formal state- 
ments of the tactics of organic evolution are too 
stiff. They tend to conceal the heart of the matter, 
of which, in Darwin’s footsteps, we are ever getting 
new glimpses, that living creatures with a will to 
live, with an insurgent self-assertiveness, with a 
spirit of adventure, with an endeavor after well- 
being, do trade with time and have commerce 
with circumstance, as genuine agents, sharing in 
their own evolution. 
