There is always a feeling of triumph when something in the ego coincides with the ego ideal. And the sense of guilt (as well as the sense of inferiority) can also be understood as an expression of tension between the ego and the ego ideal.
It is well known that there are people the general colour of whose mood oscillates periodically from an excessive depression through some kind of intermediate state to an exalted sense of well-being. These oscillations appear in very different degrees of amplitude, from what is just noticeable to those extreme instances which, in the shape of melancholia and mania, make the most painful or disturbing inroads upon the life of the person concerned. In typical cases of this cyclical depression outer exciting causes do not seem to play any decisive part; as regards inner motives, nothing more (or nothing different) is to be found in these patients than in all others. It has consequently become the custom to consider these cases as not being psychogenic. We shall refer later on to those other exactly similar cases of cyclical depression which can nevertheless easily be traced back to mental traumata.
Thus the foundation of these spontaneous oscillations of mood is unknown; we are without insight into the mechanism of the displacement of a melancholia by a mania. So we are free to suppose that these patients are people in whom our conjecture
