The Interpretation of Dreams by Sigmund Freud Chapter 3 Page 26

Whosoever has firmly accepted this censorship as the chief motive for the distortion of dreams will not be surprised to learn as the result of dream interpretation that most of the dreams of adults are traced by analysis to erotic desires. This assertion is not drawn from dreams obviously of a sexual nature, which are known to all dreamers from their own experience, and are the only ones usually described as “sexual dreams.” These dreams are ever sufficiently mysterious by reason of the choice of persons who are made the objects of sex, the removal of all the barriers which cry halt to the dreamer's sexual needs in his waking state, the many strange reminders as to details of what are called perversions.

But analysis discovers that, in many other dreams in whose manifest content nothing erotic can be found,