From a broader standpoint libido can be understood as vital energy in general, or as Bergson's _élan vital_. The first manifestation of this energy in the suckling is the instinct of _nutrition_. From this stage the libido slowly develops through manifold varieties of the act of sucking into the sexual function. Hence I do not consider the act of sucking as a sexual act. The pleasure in sucking can certainly not be considered as sexual pleasure, but as pleasure in nutrition, for it is nowhere proved that pleasure is sexual in itself. This process of development continues into adult life and is connected with a constantly increased adaptation to the external world. Whenever the libido, in the process of adaptation, meets an obstacle, an accumulation takes place which normally gives rise to an increased effort to overcome the obstacle. But if the obstacle seems to be insurmountable, and the individual renounces the overcoming of it, the stored-up libido makes a regression. In place of being employed in the increased effort, the libido now gives up the present task and returns to a former and more primitive way of adaptation. We meet with the best examples of such regressions very frequently in hysterical cases where a disappointment in love or marriage gives rise to the neurosis. There we find the well-known disturbances of nutrition, resistance against eating, dyspeptic symptoms of all sorts, etc. In these cases the regressive libido, turning away from its application to the work of adaptation, holds sway over the function of nutrition and provokes considerable disturbance. Such cases are obvious examples of regression. Similar effects of regression are to be found in cases where there are no troubles in the function of nutrition, and here we readily find a regressive revival of reminiscences of a time long past. We find a revival of the images of the parents, of the Œdipus-complex. Here things and events of infancy--never before important--suddenly become so. They are regressively reanimated. Take away the obstacle in the path of life and this whole system of infantile phantasies at once breaks down and becomes again as inactive and as ineffective as before. But do not let us forget that, to a certain extent, it is at work influencing us always and everywhere. I cannot forbear to mention that this view comes very near Janet's hypothesis of the substitution of the "parties supérieures" of a function by its "parties inférieures." I would also remind you of Claparède's conception of neurotic symptoms as emotional reflexes of a primitive nature.