Unconscious fantasy is the principal unit of psychoanalytic investigation. Though individual fantasies, either conscious or unconscious, may emphasize drive, defense, or superego interests, all fantasy life develops from a limited number of themes; these themes concern drive-related issues, experiences of helplessness, or combinations of both. Fantasy formation and fantasy content undergo developmental change. Sensorimotor, behavioral memories occur prior to fantasy and are influential in determining repetitive behavioral enactments. The complexities of infant behavior do not require the postulation of fantasy or representational memory. A complex, innate, instinctual organization of the newborn, similar in many respects to that of other newborn mammals, and distinct from the psychological organization of the older infant, is suggested as an explanation of these phenomena.