In the first place we have to get rid of the overpowering influence of an atomistic psychology. A very little study of works on psychology--particularly of the more orthodox schools--is enough to show that the social medium as a factor determining man's mental nature has been either ignored, or given a quite subordinate position. Because in studying the mental qualities of man we are necessarily dealing with an individual brain, it has been assumed that mental phenomena may be explained with no more than a casual reference to anything beyond the individual organism. This assumption may be sound so long as we are dealing with mind as the function of definitely localized organs, or if we are merely describing mental phenomena. It is when we pass to the contents of the mind, and study the significance of mental states, or enquire how they came into existence, that we find the atomistic psychology breaking down, and we find ourselves compelled to deal with mind as a psycho-sociologic phenomenon, with its relation to the social medium. Then we discover that it is man's social relationships, the innumerable generations of reaction between individual organisms and the social medium, which supply the key to problems that are otherwise insoluble. It has already been pointed out that the whole significance of morality is social. If we restrict ourselves to the individual no adequate explanation can be given of such qualities as sympathy, honesty, truthfulness, chastity, kindness, etc. Separate it in thought from the social medium and morality becomes meaningless. Properly studied, psychology yields much the same result. When we get beyond the apprehension of such fundamental qualities as time and space, heat and cold, colour and sound, the contour of man's mind, so to speak, is a social product. His feelings and impulses imply a social medium as surely as does morality. From this point of view the phrase "Social sense" is no mere figure of speech; it is the expression of a pregnant truth, the statement of something as real as any scientific law with which we are acquainted.