but the other sciences have left that point of view far behind. The comparative anatomist knows very well that external similarity is no guarantee of identity of function, or of homologous organs; and that like functions may be exercised through modes of structure which externally are characterized by the most profound and extensive differences. The same is true of the comparative philologist. It is only in the region of consciousness, in discussing myths, rites, institutions, and moral practices, that the idea persists that the important thing is to hit upon some structure which is everywhere alike. The advance which has taken place in the biological and quasi-biological sciences is sure to take place in the social sciences as well. What the biologist instinctively searches for (given as data a variety of different forms or species, with the problem of tracing their relationship) is first a common ancestor. This furnishes a point of departure and supplies one limiting term of the series under consideration. The present differentiated forms furnish the other limiting term. The problem is to discover the single process which, operating under definitely different conditions, has manifested itself in these specifically different outward forms. Knowledge of differences is just as important as that of the generic identity of the process. The function of locomotion is a mere abstraction, excepting as we can trace and define its performance through environmental conditions that give rise equally to the legless snake, the fins of the fish, the wings of the bird, and the legs of the quadruped. It is only through insight into diversification that the hold upon the process becomes vital and concrete. Similarly in morals. Supposing (which does not seem to be the case) that an identical belief regarding the duty of parental care, or of conjugal fidelity, could be discovered in human societies at all times and places. This would throw no light whatsoever upon the scientific significance of that phenomenon. On the other hand, an adequate knowledge of historical facts might throw great light upon the ethics of family relations, exhibited in complete neglect of children as well as in self-sacrificing devotion to their welfare, and in all stages of regard and disregard of personal faithfulness as between husband and wife.
