The treatment of these non-sexual aspects is of special difficulty for two reasons. In the first place, these aspects are, in their actual occurrence, intimately bound up with the processes of sexual development with which we have been dealing; and are often difficult to disentangle from them. In the second place, this very question of the distinction of the sexual from the non-sexual aspects of the observed facts of development has recently been, and still is, a subject of keen dispute among certain members of the psycho-analytic and post-psycho-analytic schools. The authors who have dealt more especially with the non-sexual aspects have written largely under the influence of this dispute and from a somewhat different point of view from that of the writers who have laid the principal emphasis upon the sexual side. Hence a comparison of the chief contributions on the two aspects is not always easy. In spite of these difficulties, however, certain conclusions stand out with some degree of clearness from the mists of controversy, and these are of considerable importance for our present purpose. [Sidenote: The work of Jung] In the course of his pioneer work, Freud himself had in more than one connection drawn attention to the importance of the family relationships in regard to the general development of character and vital activity of the individual. It is however more especially to C. G. Jung of Zürich that we are indebted for a more explicit, vigorous and extended treatment of the problems of the family from this point of view[21]. The more recent work of Jung is marred by an exaggerated insistence on a single aspect, and by a tendency to mysticism which is apt to confuse and obscure the scientific consideration of the problem. But in spite of these defects it undoubtedly contains many contributions of value and, especially when taken as complementary to, rather than opposed to, the work of Freud, Rank and others of the orthodox psycho-analytic school, it would seem to constitute in some ways an important step forward in our knowledge of the matters with which we are here concerned.