WHAT WE OWE TO DARWIN 27 



and that both left their fundamental assumption 

 from experience unexplained. 



But there is this difference between the gravi- 

 tation formula and the evolution idea, that the 

 experimental vindication of the first is easy, 

 while that of the second is, to say the least, ex- 

 tremely difficult. Whether we study the apples 

 falling in the orchard or the planets in their courses, 

 we can continually confirm the accuracy of the 

 gravitation formula, to which two centuries have 

 not added anything essential, from which two 

 centuries have taken nothing away. 



But the evolution doctrine does not rest on a 

 foundation of this sort. Like wisdom, it is justified 

 of its children by half a century's using and 

 to speak of proving it is to misunderstand it. 



Before passing from the general idea of organic 

 evolution we must point out that it is no mere 

 doctrine of the schools, but an important human 

 asset of practical and emotional, as well as of 

 intellectual value. In accepting the evolution 

 idea we lose no small part of its virtue if we do 

 not visualise it, if we do not, in some measure, 

 image the relative simplicity of life's beginnings 

 and the long pageant that has passed in gorgeous 

 procession over the earth for millions of years ; 

 if we do not understand that evolution is going 

 on still and that it includes us and our doings in 

 its sweep. 1 



1 Emile Ferriere illustrates the theory of organic evolution 

 very clearly by drawing a parallel between species and languages. 



A language may have many varieties, just as a species often 

 has. In both cases there is evidence of slow transformation and 

 of demonstrable pedigrees. Changes may be observed in actual 

 occurrence alike in languages and in organisms. It is possible 

 in both to distinguish changes arising from within (intrinsic varia- 



