The Interpretation of Dreams has come be regarded as Sigmund Freud's most significant work, one in which he would introduce his theory of the unconscious. According to Freud, dreams are forms of wish fulfillment, a sort of conflict resolution through subconscious processing of past and present troubles. Freud reasoned that the thoughts of the unconscious mind, being unruly and disturbing, were censored by the preconscious mind preventing them from passing unaltered into the conscious mind. He argued that dreams were the mechanism whereby the thoughts of the unconscious mind passed through the preconscious to the conscious mind in an altered state and thus required interpretation through psychoanalysis. "The Interpretation of Dreams" begins with an analysis of the scientific literature on the subject of dreams that predates the work, which Freud remarks is interesting but inadequate. He then discusses various types of dreams with specific examples from literature, his own dreams, and the dreams of his patients, in order to illustrate his theory.