Sigmund Freud outlines his theory of psychoanalysis, the structure and formation of the psyche, and his guidelines for conducting psychoanalysis, in addition to his theories of dreaming. He advanced in The Interpretation of Dreams the hypothesis that dreams had both an obvious or manifest meaning and a symbolic or latent meaning. Freud reported many of his own dreams and offered his interpretations. In virtually all of them, there are rich and alternate wish-fulfillment interpretations that Freud does not offer nor could we realistically expect him to. In order to explain flying dreams, Freud reverted to one of his original explanations for many wish-fulfilling dreams. Thus flying dreams, according to Freud, were a desire to be young again, to regress to a happier, more carefree state where most of our primary needs were met without effort. It is also possible that rapid eye movements (REM) incorporation of muscle atony may also explain the reports of alien abductions.