78 THE ORIGIN OF SPECIES n 



ments of scientific logic. We have ventured to 

 point out that it does not, as yet, satisfy all those 

 requirements ; but we do not hesitate to assert 

 that it is as superior to any preceding or con- 

 temporary hypothesis, in the extent of observa- 

 tional and experimental basis on which it rests, in 

 its rigorously scientific method, and in its power of 

 explaining biological phenomena, as was the 

 hypothesis of Copernicus to the speculations of 

 Ptolemy. But the planetary orbits turned out to 

 be not quite circular after all, and, grand as was 

 the service Copernicus rendered to science, Kepler s> 

 and Newton had to come after him. What if the ^ 

 orbit of Darwinism should be a little too circular ? 

 What if species should offer residual phenomena, 

 here and there, not explicable by natural selection ? 

 Twenty years hence naturalists may be in a 

 position to say whether this is, or is not, the case ; 

 but in either event they will owe the author of 

 " The Origin of Species " an immense debt of 

 gratitude. We should leave a very wrong im- 

 pression on the reader's mind if we permitted him 

 to suppose that the value of that work depends 

 wholly on the ultimate justification of the 

 theoretical views which it contains. On the con- 

 trary, if they were disproved to-morrow, the book 

 would still be the best of its kind the most 

 compendious statement of well-sifted facts bearing 

 on the doctrine of species that has ever appeared. 

 The chapters on Variation, on the Struggle for 



