As the preceding topic indicates, many provocative ideas on dreams were “in the air” at the turn of the twentieth century. Individual writers, and in some instances whole schools, had suggested that (1) dreams can be clues to the “problems and passions” of life; (2) deeper levels of the mind come to the surface during the “relaxed consciousness” of sleep; (3) dreams are often aroused by the experiences of the previous day; (4) immediate sensory impressions might also act as stimulators;(5)different people, even different races, tend to have the same type of dreams and use the same dream symbols; and(6) dreams may release both unacceptable impulses and creative ideas. These notions were widely scattered, and no comprehensive, systematic theory of dreams was presented until Sigmund Freud made his contribution.Freud. Freud’s Interpretation of Dreams, dated 1900, is regarded as his magnum opus. However, the volume was almost completely ignored by his colleagues, and it took years to exhaust the first edition of six hundred copies. The insights it contains are largely the result of the study of his own dreams—the principal technique he used in his self-analysis, undertaken after the death of his father in 1896. He had also discovered that when he applied the method of free association with his patients, they frequently related revealing dreams.The investigation of his own dreams and those of his patients led Freud to the following ideas: (1) lost memories of childhood can be recaptured by associating to dream contents; (2) many of these memories involve painful thoughts and feelings, suggesting that they had been expelled, or “repressed,” from consciousness and stored in the unconscious; dreams appear to be patterned after infantile, prelogical experience, since dream fantasies do not obey the usual laws of reality; (4) the motive force for dreams appears to stem from instinctive and predominantly sexual drives; and (5) dreams always represent the fulfillment of hidden wishes in disguised form. The last point was the most important, since it meant that dreams had meaning and could be interpreted.In developing his theory further, Freud made several other important suggestions. First, dreams are stimulated by the “day’s residues,” usually consisting of incidental details and minor incidents that touch upon unconscious impulses and memories during waking activity. Second, the reason why this unconscious material appears in disguise is that the censor—that is, our moral code or conscience—is still operative during sleep, though in attenuated form. Third, the disguises enable the individual to express his unacceptable impulses and desires, but at the same time prevent him from expressing them in such a blatant form that he would have to wake up and defend himself. In this sense the dream can be described as “the guardian of sleep.”The study of the wishes expressed in dreams and the various disguises they take gave rise to a distinction between manifest and latent content. The manifest content is the series of images and events that constitute the dream itself just as it appears to the dreamer. The latent content is the underlying meaning of the dream—the repressed wishes and impulses seeking to break through and find expression. The process by which the latent content is transformed into the manifest content is called the dream work. Three basic mechanisms are involved in this work: (a) in condensation, several meanings are fused together or combined into a single image, word, or event—e.g. dreaming of the death of a parent may stem from the patient’s childhood fear that this parent will abandon him, and at the same time reflect a guilt-laden wish that the parent will go away (death usually means simply departure to the young child); (b) in displacement, feelings or attitudes are redirected from their true object to a substitute—e.g. a child in a dream might express his hostility toward his father by breaking a male doll; (c) in symbolization, the unconscious expresses itself in symbols—a king and queen may stand for the dreamer’s parents; climbing a ladder may represent the sexual act; a pair of sisters may stand for breasts; a snake, sword, steeple, or tree may represent a penis; a purse, ravine, or book may stand for a vagina. In addition, a fourth mechanism, secondary elaboration, comes into play when the patient revises and distorts his dream in recalling and relating it.