io8 GRAND STRATEGY OF EVOLUTION 



portant than the root, the egg-germ than its food-yolk, 

 or the leaf than the flower. Rather will it be our chief 

 desire, both as laymen and as biologists, to discover how 

 each life serves the other; how each one comes, and 

 how it goes; what are the expanding buds and what 

 the withered fruits; and what, to us, is the message of 

 the whole. 



But such condensed, graphic representations of bio- 

 logical knowledge show us something more than a mere 

 genealogical tree of animal and plant life. So far as 

 it is an approximately correct record of what has taken 

 place, it also represents the successive rise and decline 

 of internal organs coincident with the rise and decline 

 of new kinds of animals and plants, and new ways of 

 living. The knowledge of that historic sequence is just 

 as firm a basis for the interpretation of causal rela- 

 tions as the observed order of events in a laboratory 

 experiment. 



For life cannot grow in vacuo. It must climb, if at 

 all, step by step on the solid footing of stabilized co- 

 operative improvements which permanently sustain 

 life at each higher level. A definite sequence of pro- 

 gressive steps, each one rightly made, is therefore im- 

 perative. 



This serial order in nature-rightness is the basis of 

 all our interpretations of natural phenomena. It car- 

 ries its own explanation all the explanation that can 

 be given. Science aims to ascertain, as nearly as may 

 be, what that sequence of creative Tightness was in or- 

 der that she may infer what it shall be. For genesis 

 is the logic of science; the source of all intellectual 

 sympathy with nature-action, and the sole justification 

 for prophecy. 



