If we consider the ethical consequences of a view of the world which, proceeding from Darwinism, permits the universe, man included, to be taken up into a mechanism of atoms--a mechanism in which everything, even the ethical action of man, finds its sufficient explanation--we certainly cannot perceive how such a view of the world is able to arrive at firm moral principles. If man, even in his spiritual life and moral action, is a mere product of nature, originated through descent, and if his whole spiritual life is fully consumed by these merely mechanical factors, then all moral principles are also nothing else than inherited customs founded upon those instincts which in the struggle for existence have proven to be the most beneficial to man. Then their influence is subject to continual change, always corresponding to the existing state of human development. As these moral instincts have displaced the former instincts of the animal predecessors of man--say, _e.g._, of sharks, of marsupialia, of lemurides--so they must {380} also expect it any time to be displaced in turn by new and still more useful instincts. And even in the same period of the development of mankind, the moral or immoral principles which have actual authority in each nation or tribe, have their full right of existence as long as they are not displaced by still more advantageous instincts. Moral principles in which infanticide, prostitution, and cannibalism have a place, are inferior to the highest form of Christian morality only so far as they do not hold their own in the struggle for existence, when nations having those low views come into collision with nations of higher moral culture; but in themselves they have full value and full right, so long as they attain the end of all instincts, and so far as we can speak of ends at all; in such naturalism, apart from human activity, the end consists only in the preservation of the individual and the species in the struggle for existence.