In the few years of our childhood, we have to cover the enormous distance of development from primitive man of the Stone Age to civilized man of today. In addition to this tremendous burden, the child has to ward off the urges of an early sexuality. Small wonder, then, that our “I” takes recourse to repressions, thus exposing itself to childhood neuroses, the effects of which in turn furnish the disposition for nervous disturbances in more mature years. Everything now depends upon how the growing up individual will be treated by fate. If life is too hard, the divergence between urges and the opposition of reality too great, the “I” may remain unsuccessful in its endeavors to mediate between the two. This is the more probable, the more the “I” is encroached upon by such infantile dispositions as it may have acquired in tender years. Thus, the process of repression is repeated; urges tear themselves free from the sovereignty of the “I” to gain, by way of regression, a substitute for the gratification they crave, while the poor “I” has become helplessly neurotic. Let us hold on firmly to this: that the most important, the pivotal point in the whole situation, so to speak, is the relative strength of the “I” in all its phases. It is easy, then, to complete our whole etiological survey, that is our endeavor to assign causes to the phenomena observed. We already know the normal causes for nervousness to be the infantile weakness of the “I,” the checking of early sexual urges, and the influence of chance episodes in our childhood. But is there no possibility that there are also some other contributory factors, antedating childhood? For example, an inborn strength and unruliness of those urges which constitute the “It,” presenting right from the very start a task much too difficult for the “I”? Or could a certain weakness, existing for reasons unknown, in the development of the “I” be held responsible? Of course, all these possibilities will exert an etiological importance, in some cases of surpassing value. The specific driving power of the “It” must always be taken into consideration, and wherever it is developed to an excessive degree, there are only meagre chances for a successful application of our therapy. Of the reasons that block the development of the “I,” we still know too little to account for such cases of neurosis which arise on a constitutional basis. It may be assumed that neurosis hardly ever develops unless there are constitutional or congenital factors increasing the possibility for such a condition. However, if it is correct that the relative weakness of the “I” is the deciding factor for the development of neuroses, then it would also appear possible that later, physical disturbances may result in a neurosis provided it also results in a weakening of the “I.”