origin of all species by descent is now an established fact. Some of the clergy themselves accept it, and try to reconcile Evolution with Revelation.
Darwin's work gave at the same time a new key and a new method of investigation for the better understanding of many other groups of phenomena: the life of physical matter, the life of organisms, and the life and evolution of societies. The idea of a continuous development—of a progressive Evolution and a gradual adaptation of beings and societies to new conditions, in proportion as these conditions become modified—this idea found a far wider field to work in than that of merely explaining the origin of new species. When it was applied to the study of Nature in general, as well as to the study of man and his social institutions, it opened up quite new horizons and made it possible to explain some of the most difficult problems in the domain of all branches of knowledge. Taking this principle, so rich in consequences, as a basis, it was possible to reconstruct, not only the history of organisms, but also the history of human institutions.
Biology, in the hands of Herbert Spencer, showed us how all the species of plants and animals inhabiting our globe were able to develop, starting from a few very simple organisms that existed on the earth at the beginning; and Haeckel was able to draw a sketch of a likely genealogical tree of the different classes of animals, man included. This was already a great result; but it also became possible to lay a solid scientific foundation to the history of human customs, beliefs, and institutions—a knowledge the want of which was so much felt by the philosophers of the eighteenth century and called for by Auguste Comte. Now, the history of human societies, institutions and religions can be written from the point of view of adaptive Evolution, without having recourse to the metaphysical formulas of Hegel, and without resorting to "innate ideas," to revelation from above, or to Kant's "substances." We can reconstrue it without appealing to those formulas which were death to the spirit of research, and behind which the same ignorance was always hidden—the same old superstition, the same blind faith disguised under sonorous words.
Aided by the works of naturalists on the one hand, and, on the other, by the works of Henry Maine and his followers, who applied the same inductive method to the study of primitive institutions and to the law codes that originated from them,
