In the third part of the work, Madame Royer treats of the development of human society. Everything permits the supposition that from a very remote period the anthropoid primate that served as the root stock of man became omnivorous, with a predominance of carnivorous tastes. These conditions of life therefore invoked an at least rudimentary social instinct--that is, animals lived in troops collected under chiefs, with a tactics for mutual defense. The most ancient documents, in fact, show the human species living in rival or allied tribes. Hunting and fishing were the principal business of these primitive races, which relied for assistance at first on their agility, muscular strength, and arms of stone of a workmanship still in its infancy. Flint was then very roughly cut. But now a great advance was achieved for man, a step toward industry and civilization. This second stage was the discovery of fire, an immediate consequence of the cutting of flints, when sparks would fly out at each blow. Yet a later epoch probably had to be reached for the real employment of fire in cooking food. Previous to that it could serve man only for warming himself, or for protecting himself at night against wild beasts. Next came the earliest industries--the potter's art, the making of rude clothing, and the construction of habitations; and about this time the instinct of property begins to develop. For a long time there are no other securities than force. On the other hand, the diversities of the faculties, which are very unequally distributed among the various races, and even among the different individuals of each of them, create social inequalities, the chief cause of the crime, wars, and misery with which every page of the history of man is soiled, and from which the original organization of civil society sprang. At the close of her treatise the eminent anthropologist states the formula of the highest social prosperity: she believes that it resides in an equal liberty for each member of a national collectivity and in the free play of individual initiatives. Man will work in as large a sphere of action as the right of another leaves him, striving to broaden his place at the feast of life. Each one will climb the social ladder in his own way and will fix himself on the step on which his aptitudes will meet the best reward. Each individual will therefore gain a large sum of well-being, and the species will possess a total maximum of enjoyment. Such, in broad outline, is the substance of this book, which naturalists and philosophers have consulted now for many years. It is not within the province of our sketch to dwell upon any of the bold assertions and hypotheses in it that have been invalidated by later geological discoveries; and, notwithstanding a few errors in detail, almost inevitable in a book of the kind, the _Origine de l'Homme_ is, as a whole, a work as vigorously thought out as clearly and generously written.