The Interpretation of Dreams by Sigmund Freud Chapter 1 Page 31

is nothing else than a wish realized. On account of poliomyelitis a girl, not quite four years of age, was brought from the country into town, and remained over night with a childless aunt in a big — for her, naturally, huge — bed. The next morning she stated that she had dreamt that the bed was much too small for her, so that she could find no place in it. To explain this dream as a wish is easy when we remember that to be “big” is a frequently expressed wish of all children. The bigness of the bed reminded Miss Little-Would-be-Big only too forcibly of her smallness. This nasty situation became righted in her dream, and she grew so big that the bed now became too small for her.

Even when children's dreams are complicated and polished, their comprehension as a realization of desire is fairly