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,
