the work of conquest went rapidly on. Day
by day squads of the enemy capitulated and struck their arms. By the
time another score of years had passed the doctrine of evolution had
become the working hypothesis of the scientific world. The revolution
had been effected.

And from amid the wreckage of opinion and belief stands forth the figure
of Charles Darwin, calm, imperturbable, serene; scatheless to ridicule,
contumely, abuse; unspoiled by ultimate success; unsullied alike by
the strife and the victory--take him for all in all, for character, for
intellect, for what he was and what he did, perhaps the most Socratic
figure of the century. When, in 1882, he died, friend and foe alike
conceded that one of the greatest sons of men had rested from his
labors, and all the world felt it fitting that the remains of Charles
Darwin should be entombed in Westminster Abbey close beside the honored
grave of Isaac Newton. Nor were there many who would dispute the justice
of Huxley's estimate of his accomplishment: "He found a great truth
trodden under foot. Reviled by bigots, and ridiculed by all the world,
he lived long enough to see it, chiefly by his own efforts, irrefragably
established in science, inseparably incorporated with the common
thoughts of men, and only hated and feared by those who would revile but
dare not."

THE ORIGIN OF THE FITTEST

Wide as are the implications of the great truth which Darwin and his
co-workers established, however, it leaves quite untouched the problem
of the origin of those "favored variations" upon which it operates.
That such variations are due to fixed and determinate causes no one
understood better than Darwin; but in his original exposition of his
doctrine he made no assumption as to what these causes are. He accepted
the observed fact of variation--as constantly witnessed, for example, in
the differences between parents and offspring--and went ahead from this
assumption.

But as soon as the validity of the principle of natural selection came
to be acknowledged speculators began to search for the explanation of
those variations which, for purposes of argument, had been provisionally
called "spontaneous." Herbert Spencer had all along dwelt on this phase
of the subject, expounding the Lamarckian conceptions of the direct
influence of the environment (an idea which had especially appealed
to Buffon and to Geoffroy Saint-Hilaire), and of effort in response to
environment and stimulus