450 Evolution and Modern Philosophy 
concerning the evolution of species ; the idea of species would in his 
eyes absolutely lose its importance if a transition from species to 
species under the influence of conditions of life were admitted. His 
disciples (Littré, Robin) continued to direct against Darwin the 
polemics which their master had employed against Lamarck. Stuart 
Mill, who, in the theory of knowledge, represented the empirical or 
positivistic 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. 
IIL. j 
Darwin’s energetic renewal of the old idea of evolution had its 
chief importance in strengthening the conviction of this real con- 
tinuity 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 @ priori. 
