Robbers, burglars at night, and ghosts, of which we are afraid before going to bed, and which occasionally even disturb our sleep, originate in one and the same childish reminiscence. They are the nightly visitors who have awakened the child to set it on the chamber so that it may not wet the bed, or have lifted the cover in order to see clearly how the child is holding its hands while sleeping. I have been able to induce an exact recollection of the nocturnal visitor in the analysis of some of these anxiety dreams. The robbers were always the father, the ghosts more probably corresponded to feminine persons with white night-gowns. When one has become familiar with the abundant use of symbolism for the representation of sexual material in dreams, one naturally raises the question whether there are not many of these symbols which appear once and for all with a firmly established significance like the signs in stenography; and one is tempted to compile a new dream-book according to the cipher method. In this connection it may be remarked that this symbolism does not belong peculiarly to the dream, but rather to unconscious thinking, particularly that of the masses, and it is to be found in greater perfection in the folklore, in the myths, legends, and manners of speech, in the proverbial sayings, and in the current witticisms of a nation than in its dreams. The dream takes advantage of this symbolism in order to give a disguised representation to its latent thoughts. Among the symbols which are used in this manner there are of course many which regularly, or almost regularly, mean the same thing. Only it is necessary to keep in mind the curious plasticity of psychic material. Now and then a symbol in the dream content may have to be interpreted not symbolically, but according to its real meaning; at another time the dreamer, owing to a peculiar set of recollections, may create for himself the right to use anything whatever as a sexual symbol, though it is not ordinarily used in that way. Nor are the most frequently used sexual symbols unambiguous every time.