The Interpretation of Dreams by Sigmund Freud Chapter 5 Page 14

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