78 THE ORIGIN OF SPECIES 
ments of scientific logic. We have ventured 
point out that it does not, as yet, satisfy all thos 
requirements; but we do not hesitate to assert 
that it is as superior to any preceding or cor 
temporary hypothesis, in the extent of observa- 
tional and experimental basis on which it rests, 
its rigorously scientific method, and in its power 
explaining biological phznomena, as was th 
hypothesis of Copernicus to the speculations 
Ptolemy. But the planetary orbits turned out te 
be not quite circular after all, and, grand as was 
the service Copernicus rendered to science, Kepler 
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 ol 
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 
