EVOLUTION IN NATURAL SCIENCE 7 



struction which reduces itself to a theory. It is 

 only capable of giving us a higher or lower degree 

 of probability as to the processes of historical develop- 

 ment, but the evolution of a race does not admit 

 of being demonstrated by observation or experi- 

 ment. Nothing else indeed is possible, for man 

 appeared upon the earth as an epigonos (i.e. an 

 after-born), who came into existence at the close of 

 a course of evolution that had lasted millions of 

 years. When he looks back he sees only monu- 

 ments, ruins, and traces of previous evolutions; 

 and he cannot even survey the evolution itself, 

 he can only obtain some conception of it by way 

 of inference, after a careful and impartial com- 

 parison of very various pieces of evidence. 



The doctrine of evolution is therefore not an 

 experimental science, and can never be one. It 

 is essentially a theory based upon a group of hypotheses 

 which are in harmony with one another, and afford 

 the most probable explanation of the origin of organic 

 species. We cannot demand to see the evolution 

 of species taking place before our eyes, in such a 

 way as to give us a direct confirmation of the 

 theory of evolution. Man was born far too late, 

 and lives far too short a time, to be able to make 

 such a demand. Imagine a fly, destined to live 

 but one day, which comes to life one beautiful 

 morning in spring, and sees all around it the trees 

 in full blossom. That the blossoms came forth 

 from buds which gradually unfolded, and that the 



