movement in
philosophy--like his English forerunners from Locke to Hume--founded
his theory of knowledge and morals on the experience of the single
individual. He sympathised with the theory of the original likeness of
all individuals and derived their differences, on which he practically
and theoretically laid much stress, from the influence both of
experience and education, and, generally, of physical and social causes.
He admitted an individual evolution, and, in the human species, an
evolution based on social progress; but no physiological evolution of
species. He was afraid that the hypothesis of heredity would carry us
back to the old theory of "innate" ideas.

Darwin was more empirical than Comte and Mill; experience disclosed to
him a deeper continuity than they could find; closer than before the
nature and fate of the single individual were shown to be interwoven in
the great web binding the life of the species with nature as a whole.
And the continuity which so many idealistic philosophers could find
only in the world of thought, he showed to be present in the world of
reality.

III.

Darwin's energetic renewal of the old idea of evolution had its chief
importance in strengthening the conviction of this real continuity in
the world, of continuity in the series of form and events. It was a
great support for all those who were prepared to base their conception
of life on scientific grounds. Together with the recently discovered law
of the conservation of energy, it helped to produce the great realistic
movement which characterises the last third of the nineteenth century.
After the decline of the Romantic movement people wished to have firmer
ground under their feet and reality now asserted itself in a more
emphatic manner than in the period of Romanticism. It was easy for Hegel
to proclaim that "the real" was "the rational," and that "the
rational" was "the real": reality itself existed for him only in the
interpretation of ideal reason, and if there was anything which could
not be merged in the higher unity of thought, then it was only an
example of the "impotence of nature to hold to the idea." But now
concepts are to be founded on nature and not on any system of categories
too confidently deduced a priori. The new devotion to nature had its
recompense in itself, because the new points of view made us see that
nature could indeed "hold to ideas," though perhaps not to those which
we had cogitated beforeha