Dreaming is generally defined as imaginal, sensory, motor, and thought processes occurring during sleep. Neither sleep nor dreaming however can be precisely defined. Dreaming depends on how it is measured and in which of the four basic stages of sleep it occurs in. Dreaming takes places in varying degrees in all stages of sleep. Dreams are not necessarily visual imagery as blind people dream in auditory and sensory motor modes.
Dreaming has always been the subject of controversy. Egyptian papyrus documents dating back to 2000 B.C. discussing dreams and their interpretations. In ancient Greece the dreamer was to be in contact with the Gods. Hippocrates, Aristotle, and Galen believed that dreams often contained physiological information that heralded future medical illnesses. In succeeding centuries, Sigmund Freud led the modern age of dream research in his monumentally original book of the Interpretations of Dreams. According to Freud, dreams are disguised thoughts from the unconscious mind. Freud spoke about Manifest Content, which being the obvious but the superficial, meaning of dreams and also about the Latent Content , which was the true meaning of dreams that is found in the symbols in their Manifest Content. Freud's theories have always been objected and tested by many. C. G. Jung challenged Freud's position but retained and even expanded his metaphors. Jung began to insist first on the primacy and then on the exclusive validity of the manifest dream. He stated that the manifest dream picture is the dream itself and contains the whole meaning of the dream. Jung stressed reading the dream as text metaphor prior to the interpretation. He gradually moved from Freud's free association toward a method that he called amplification which is extending and deepening the dream content with images from a variety of sources. Jung's awareness that interpretation depended completely on that initial process of reading is conformed by practicing translators.