human consciousness they have seemed to make the individual at every point the creation of social conditions, losing sight of the rhythm between the individual consciousness and social consciousness whereby each is enabled to live more fully. They have proceeded, too, in the main, on the assumption that in the savage society we have the culture society at a lower historical point, and that the laws of social growth can be understood only in their most crude manifestations. In this they resemble those biologists who assume that the laws of growth can be adequately determined from a study of micro-organisms. But in determining the chemistry of digestion, for example, the physiologist must work with masses larger and more highly organized than the amœba; and the social structure of savage communities, while very suggestive, is likewise often too incomplete, when taken alone, for the purpose of the folk-psychologist. A knowledge of the present must be combined with the knowledge of the past for an adequate understanding of any part of the past. The nature-peoples are not communities in process of becoming culture-peoples; they are as old as we, and in the very fact that they have not become like us we may hope to find the laws of social physics which raised us above them.
Herbart, who must be regarded as the pioneer in folk-psychology, declared that "ideas move in our minds with as much regularity as the stars move in the heavens." The discovery of the law of parallelism in the customs and culture of different tribes and races is a confirmation of this view, and suggests the necessity of a method more fundamental than any based on race differences; and in order to secure a fundamental basis of procedure we shall be wise if we avail ourselves of the knowledge recently brought to light by physiologists in connection with the phenomena of irritability in general. Irritability is the distinctive property of living matter. It is that quality of plants and animals in virtue of which stored up energy is set free by an external stimulus; it is therefore the basis of all somatic and psvchic life. We are familiar with the fact that animals having special organs of sense receive through them
