ccount. The investigations of
Darwin, which brought them into the foreground, naturally promoted
attempts to discover in them the chief key to the growth of
civilisation. Comte had expressly denounced the notion that the
biological methods of Lamarck could be applied to social man. Buckle
had taken account of natural influences, but had relegated them to a
secondary plane, compared with psychological factors. But the
Darwinian theory made it tempting to explain the development of
civilisation in terms of "adaptation to environment," "struggle for
existence," "natural selection," "survival of the fittest," etc.[240]

The operation of these principles cannot be denied. Man is still an
animal, subject to zoological as well as mechanical laws. The dark
influence of heredity continues to be effective; and psychical
development had begun in lower organic forms,--perhaps with life
itself. The organic and the social struggles for existence are
manifestations of the same principle. Environment and climatic
influence must be called in to explain not only the differentiation of
the great racial sections of humanity, but also the varieties within
these sub-species and, it may be, the assimilation of distinct
varieties. Ritter's _Anthropogeography_ has opened a useful line of
research. But on the other hand, it is urged that, in explaining the
course of history, these principles do not take us very far, and that
it is chiefly for the primitive ultra-prehistoric period that they can
account for human development. It may be said that, so far as concerns
the actions and movements of men which are the subject of recorded
history, physical environment has ceased to act mechanically, and in
order to affect their actions must affect their wills first; and that
this psychical character of the causal relations substantially alters
the problem. The development of human societies, it may be argued,
derives a completely new character from the dominance of the conscious
psychical element, creating as it does new conditions (inventions,
social institutions, etc.) which limit and counteract the operation of
natural selection, and control and modify the influence of physical
environment. Most thinkers agree now that the chief clews to the
growth of civilisation must be sought in the psychological sphere.
Imitation, for instance, is a principle which is probably more
significant for the explanation of human development than natural
selection. Darwi