Freud, in his introductory chapter to The Interpretation of Dreams (Freud, 1955b, 41–42) comments, “Even when investigation shows that the primary exciting cause of a phenomenon is psychical, deeper research will one day trace the path further and discover an organic base for the mental event.” Freud rejected the speculative theories of his colleagues who wished to assign the dreaming process solely to demonstrable organic causes. The great psychologist of dreaming believed that his psychological descriptions of dream formation would at some time be related to organic (i.e., brain) activity. I believe it is the conviction that biology, the brain, is real and psychology, the dream, is ephemeral that supports the attraction of clinicians and researchers to biological explanations for experiential events.