In this place I shall only follow up one of the consequences which seem possible from this point of view, thus resuming the discussion of a problem which I was obliged to leave unsolved elsewhere.[61] Each of the mental differentiations that we have become acquainted with represents a fresh aggravation of the difficulties of mental functioning, increases its instability, and may become the starting-point for its breakdown, that is, for the onset of a disease. Thus, by being born we have made the step from an absolutely self-sufficient narcissism to the perception of a changing outer world and to the beginnings of the discovery of objects. And with this is associated the fact that we cannot endure the new state of things for long, that we periodically revert from it, in our sleep, to our former condition of absence of stimulation and avoidance of objects. It is true, however, that in this we are following a hint from the outer world, which, by means of the periodical change of day and night, temporarily withdraws the greater part of the stimuli that affect us. The second example, which is pathologically more important, is not subject to any such qualification. In the course of our development we have effected a separation of our mental existence into a coherent ego and into an unconscious and repressed portion which is left outside it; and we know that the stability of this new acquisition is exposed to constant shocks. In dreams and in neuroses what is thus excluded knocks for admission at the gates, guarded though they are by resistances; and in our waking health we make use of special artifices for allowing what is repressed to circumvent the resistances and for receiving it temporarily into our ego to the increase of our pleasure. Wit and humour, and to some extent the comic in general, may be regarded in this light. Everyone acquainted with the psychology of the neuroses will think of similar examples of less importance; but I hasten on to the application I have in view. It is quite conceivable that the separation of the ego ideal from the ego cannot be borne for long either, and has to be temporarily undone. In all renunciations and limitations imposed upon the ego a periodical infringement of the prohibition is the rule; this indeed is shown by the institution of festivals, which in origin are nothing more nor less than excesses provided by law and which owe their cheerful character to the release which they bring.[62] The Saturnalia of the Romans and our modern carnival agree in this essential feature with the festivals of primitive people, which usually end in debaucheries of every kind and the transgression of what are at other times the most sacred commandments. But the ego ideal comprises the sum of all the limitations in which the ego has to acquiesce, and for that reason the abrogation of the ideal would necessarily be a magnificent festival for the ego, which might then once again feel satisfied with itself.[63]