into consciousness as soon as a break in the established custom occurs; in other words, our rationalistic explanation will depend upon the character of the associated ideas. It is therefore of great importance to know whence the associated ideas are derived, particularly in how far we may assume that these associations are stable. It is not quite easy to give definite examples of changes of such associations in our civilization, because, on the whole, the rationalistic tendencies of our times have eliminated many of the lines of association, even where the emotional effect remains; so that the change, on the whole, is one from existing associations to loss of associations. We may sum up these observations by saying, that, while each habit is the result of historical causes, it may in course of time associate itself with different ideas. As soon as we become conscious of an association between a habit and a certain group of ideas, we are led to explain the habit by its present associations, which probably differ from the associations prevailing at the time when the habit was established. We will now turn to a consideration of analogous phenomena in primitive life. Here the dislike of that which deviates from the custom of the land is even more strongly marked than in our civilization. If it is not the custom to sleep in a house with feet turned towards the fire, a violation of this custom is dreaded and avoided. If in a certain society members of the same clan do not intermarry, the most deep-seated abhorrence against such unions will arise. It is not necessary to multiply examples, for it is a well-known fact that the more primitive a people, the more it is bound by customs regulating the conduct of daily life in all its details. I think we are justified in concluding from our own experience, that as among ourselves, so among primitive tribes, the resistance to a deviation from firmly established customs is due to an emotional re-action, not to conscious reasoning. This does not preclude the possibility that the first special act, which became in course of time customary, may have been due to a conscious mental process; but it seems to me likely that many customs came into being without any conscious activity. Their development must have been of the same kind as that of the categories which are reflected in the morphology of languages, and which can never have been known to the speakers of these languages. For instance, if we accept Cunow’s theory of the origin of Australian social systems,[8] we may very well say that originally each generation kept by themselves, and therefore marriages between members of two succeeding generations were impossible, because only marriageable men and women of one generation came into contact. Later on, when the succeeding generations were not so diverse in age, and their social separation ceased, the custom had been established, and did not lapse with the changed conditions.