It may be objected to this book that both animals and men are represented in it under too favourable an aspect; that their sociable qualities are insisted upon, while their anti-social and self-asserting instincts are hardly touched upon. This was, however, unavoidable. We have heard so much lately of the "harsh, pitiless struggle for life," which was said to be carried on by every animal against all other animals, every "savage" against all other "savages," and every civilized man against all his co-citizens--and these assertions have so much become an article of faith--that it was necessary, first of all, to oppose to them a wide series of facts showing animal and human life under a quite different aspect. It was necessary to indicate the overwhelming importance which sociable habits play in Nature and in the progressive evolution of both the animal species and human beings: to prove that they secure to animals a better protection from their enemies, very often facilities for getting food and (winter provisions, migrations, etc.), longevity, therefore a greater facility for the development of intellectual faculties; and that they have given to men, in addition to the same advantages, the possibility of working out those institutions which have enabled mankind to survive in its hard struggle against Nature, and to progress, notwithstanding all the vicissitudes of its history. It is a book on the law of Mutual Aid, viewed at as one of the chief factors of evolution--not on all factors of evolution and their respective values; and this first book had to be written, before the latter could become possible.