treated in the fourth paper; it may be added here that no race or condition of men is known in which association does not exist. We may therefore assume that it took place very early, and probably at a wholly subhuman stage. It was doubtless one of the most powerful mutual factors in the rapid brain-development mentioned in that paper. This brain-development was the condition of the psychic element which made man a creator, the master instead of the slave of his environment, and which above all else distinguishes him from the rest of nature. The first and foremost, then, of all the productions of this being is society itself, considered as an artificial institution. For however early it may have come into existence, it is to be distinguished from all animal societies as the product of reason instead of a product of instinct. It is this and this alone which constitutes it an institution. The study of this institution from this point of view, in its most embryonic stages and among the least developed races, therefore constitutes one of the most important fields of research, and comes clearly under the head of sociological data.
About the first subject to which associated man turned his attention must have been the proper care of the young. Natural selection alone would secure this, since those who neglected it would be eliminated. This is the basis of the institution of marriage, and a careful survey of the various forms which this institution has assumed, both in primitive and advanced races, shows that it is in all cases more or less successfully adapted to this end. Even polyandry, which prevails in some districts of Thibet, and which seems so repugnant to our ideas, has been shown to be the best form of marriage for a people leading the kind of life which is required in such a country, where a portion of the men are obliged to absent themselves from home for a large part of the time. It is not enough to observe and record the customs of a people; sociology, scientifically studied, inquires into the reasons that underlie customs.
The institution of government doubtless grew out of that of the family. The latter was not always, and is not everywhere, restricted to the narrow degrees of kinship that we recognize as
