In this respect then the channels comprising the sentiment of parent-love are comparable to all other early channels of the Libido. Just as the autoerotic trends connected with the oral, anal and urethral regions of the body and the primitive tendencies to sadism, masochism and exhibitionism have been shown to underlie many of the activities of adult life, so (on a higher and more complex level of development) parent-love has been revealed as the foundation upon which rests the greater part of the affection of childhood, adolescence and maturity. From this point of view it would appear that parent-love, in its persistence and influence on later life, exhibits characteristics which are, in greater or less degree, common to all the earliest manifestations of the Libido. [Sidenote: Furthermore, numerous influences favour its persistence] In one important respect however the history of parent love differs from the history of many other of these early manifestations. Parent-love not only comes into being at a very early age, but, as regards many of its attributes, it normally persists with but little alteration throughout the whole of the impressionable period from infancy to adolescence. The sensual elements of this love are, it is true, for the most part repressed soon after they appear, but the elements of tenderness and veneration usually remain and build up a sentiment which operates vigorously and continuously for many years, whereas the other sentiments formed during this period (with the exception again of the self-regarding sentiment) are apt to be of a far more temporary and evanescent character. It is true, as we have seen, that as development proceeds the affection felt towards the parents is to some extent displaced on to other persons, but nevertheless, in the normal course of events, a large portion of this affection remains throughout early life fixated on its original object. Moreover as regards this fixation of affection on the parents (provided only no sensual element be too apparent), the individual meets as a rule with every encouragement and sign of approval from those about him, not with the disapprobation or ridicule which he often encounters when his affections are directed elsewhere. The sentiment of parent love has therefore the support of moral sanction in a way enjoyed by few, if any, other sentiments of love that may be formed in early life. We see therefore that both as regards priority of formation and as regards duration, vigour and continuity of function throughout the all important period of development, parent love normally occupies an almost unique place among the sentiments--a place which renders to some extent intelligible the importance of the role it plays in human life. [Sidenote: The tendency to incest thus brought about is strengthened by practice and tradition]