In view of the fact that there is no expression of mental activity which does not appear in the dream, I believe that the only description of the nature of dreams that does not distort or narrow down the phenomenon is the broad one that dreaming is a meaningful and significant expression of any kind of mental activity under the condition of sleep. (…) My assumption is that dreams can be the expression both of the lowest and most irrational and of the highest and most valuable functions of our minds. ― (1951a: The Forgotten Language. An Introduction to the Understanding of Dreams, Fairy Tales and Myths, New York (Rinehart and Co.) 1951, p. 25 and 47.)