Philosophy of the Unconscious of the scales, and his 'World-process' in the other. There are some who believe they weigh equally; for in each scale there is an evil word—and a good joke." Hartmann's work has been seen as preparing the way for Freud's later theory of the unconscious. Freud consulted "Philosophy of the Unconscious" while writing "The Interpretation of Dreams" (1899), in which he called Hartmann the firmest opponent of the theory that dreams are wish fulfillments. The philosopher Hans Vaihinger was influenced by "Philosophy of the Unconscious", relating in his "The Philosophy of 'As if'" (1911) how it led him to Schopenhauer.
Dream interpretation treatise on dreams, in which he was the first to distinguish between dream interpretation and the nature and causes of dreams. In "The Canon of Medicine", Avicenna extended the theory of temperaments to encompass "emotional aspects, mental capacity, moral attitudes, self-awareness, movements and dreams." Ibn Khaldun's "Muqaddimah" (1377) states that "confused dreams" are "pictures of the imagination that are stored inside by perception and to which the ability to think is applied, after (man) has retired from sense perception." Ibn Shaheen states: Interpretations change their foundations according to the different conditions of the seer (of the vision),so seeing handcuffs during