It seems at first sight that there is something immediately evident and instinctively plausible in this fashion of reasoning, which it may be said is principally distinguished by its abuse of analogy and by its haste in drawing conclusions. Man is without doubt an animal, and he is linked by connections of descent and affinity to other animals. He has no privileges of origin or of elementary structure, and his organism is merely one particular case of general physiology. His first immediate field was that of simple nature not modified by work, and from thence are derived the imperious and inevitable conditions of the struggle for existence, with the consequent forms of adaptation. Thence are born races in the true and authentic sense of the word; that is to say, in so far as they are immediate determinations of black, white, yellow, woolly-haired, straight-haired, etc., and not secondary historico-social formations, that is to say, peoples and nations. Thence are born the primitive instincts of sociability and in life in promiscuity arise the first rudiments of sexual selection. But if we can reconstruct in imagination the primitive savage, by combining our conjectures, it is not given us to have an empirical intuition of him, just as it is not given us to determine the genesis of that hiatus, that is to say, that break in continuity, thanks to which human life is found detached from animal life to rise, in the sequel, to an ever higher level. All men who live at this moment on the earth's surface and all those who, having lived in the past, were the objects of any trustworthy observation, are found, and were found, already sufficiently removed from the moment when purely animal life had ceased. A certain social life with customs and institutions, even if it be of the most elementary form that we know, that is to say, of the Australian tribes, divided into classes and practising the marriage of all the men of one class with all the women of another class, separates human life by a great interval from animal life. If we consider the _maternal gens_, of which the classic type, the Iroquois type, has, thanks to Morgan's work, revolutionized prehistoric science, while giving us at the same time the key to the origins of history properly so called, we have a form of society already much advanced by the complexity of its relations. At that stage of social life which, according to our knowledge, seems very elementary, that is to say, in the Australian society, not only does a very complicated language differentiate men from all other animals (and language is a condition and an instrument, a cause and an effect of sociability), but the specialization of human life, apart from the discovery of fire, is manifested by the use of many other artificial means by which the needs of life are satisfied. A certain territory acquired for the common use of a tribe, a certain art of hunting--the use of certain instruments of defense and attack and the