I am prompted to this inquiry by two reasons: in the first place, the origin of the maternal-system and the subsequent association of the mother and the father appear to me to afford evidence of the working of a natural law of the two sexes, which, both for social and other reasons, is of great interest in the present stage of women’s history. The establishing of the mother’s position is of great importance. If we can prove that women have exercised unquestioned and direct authority in the past history of human societies, we shall be in a position to answer those who to-day wish to set limits to women’s activities. Then, in the second place, I am compelled to doubt certain conclusions, both of those who accept mother-right, and also of the greater number who now deny its occurrence. If I am right, and the importance of the maternal family has been unduly neglected and the true explanation of its origin overlooked, I feel that, whatever errors I may fall into, I am justified in undertaking this task. My mistakes will be corrected by others with more knowledge than I can claim; and if my theory of mother-right has any merit, it will be established in more competent hands. The vast majority of investigators on these questions are men. I am driven to believe that sometimes they are mistaken in their interpretation of habits and customs which arose among primitive societies in which the influence of women was marked. In dealing with the family and its origin it has been usual to consider the male side and to pass over the female members. This has led, I am sure, to much error. The custom of tracing descent through the mother, either practised consciously and completely, or only as a survival, occurs among many primitive peoples in all parts of the world. Whether, however, it existed universally and from all time, or whether only in certain races, among whose institutions it remains or may still be traced, is a much debated question. Not all barbarous tribes are in the stage of mother-right; on the contrary many reckon descent through the father. But even where the latter is the case, vestiges of the former system are frequently to be found. There seems to be a common tendency to discredit a system of relationship, which suggests even as a bare possibility the mother, and not the father, being the head of the family. Yet, I believe I can assign some, at least plausible, reasons for believing that descent through women has been a stage, though not, I think, the first stage, in social growth for all branches of the human family.