This article explores the psychological and literary aspects of the Der Doppelgänger, The Double. A Double is related to the concept of multiple personality. Such mental conditions are classified as instances of dissociation. However, a much earlier history of a Double exists in literature rather than in psychology. In the literary past, a "Double-Personality" embodied the creative imagination of writers. Aspects of this condition have been reported in all cultures. In some societies a "Double-Personality" is thought to manifest great power whereas in others it represents illness. After Freud, writers fostered psychoanalytic speculations about this condition. The dynamic issues of this condition are discussed together with literary examples by world famous authors. Persons manifesting this condition frequently employ symbols, allegory, and other creative devices. While reason, observation, and experiment are the modes of science, appreciating the symbolic behavior associated with this condition is also important. Clinicians and others should carefully attend to how symbolic behavior may be employed by patients to describe symptoms of their condition not easily conveyed with clarity by complete rationality. There is special value in recognizing how persons may utilize this condition to further their fictive goals. Without this understanding, treatment may be less effective and improvement may not occur.