The belief that dreams have a special significance is practically universal. They have been an object of curiosity in all cultures and all times, and have been variously interpreted as portents of the future, the handiwork of gods or demons, guides to the solution of problems, the wandering of the soul in the spirit world—and, most recently, a key to the unconscious, an instrument in psychotherapy, and a basic contributor to mental health.Dream interpretation, or “oneirology,” has had such a long and varied history that we will only be able to note a few of the highlights from earlier periods as a preface to modern theories. There is evidence that dreams were recorded as soon as man developed a written language. The first known “dream book,” the Chester Beatty papyrus, contains material dating back to 2000 B.C., and indicates that dreams played an important part in the magic, religion, and government of the early Egyptians. There is evidence that their beliefs were borrowed from the Assyrians and Mesopotamians; at any rate, in all three of these societies dreams were viewed as manifestations of either gods or demons, and as revelations of an invisible world which cannot be experienced in the waking state.The two hundred dreams contained in the papyrus are interpreted as warnings of future events, advice on the treatment of illness, and guidance on affairs of state, success in love, and other ventures—for example, sawing wood predicts the defeat of an enemy,and dreaming of a funeral is an omen of long life (an example of the “law of contrast” later applied by Freud). The papyrus also contains rituals and incantations to ward off the effects of threatening dreams produced by demons, as well as prescriptions for potions to be used in overcoming infertility. The priests of the time took over the ritual aspects of dreaming, and one sect utilized “incubation,” a practice in which sick persons slept on a temple floor in order to learn, through dreams, what treatments would be most effective.The early Hebrews followed the same pattern, except for their monotheistic belief that God alone is the source of revelations occurring in dreams— for example, the prophecy of the flight from Egypt. Later, the Talmud held that dreams occurring just before waking are particularly vivid and significant, and when they occur in a series, later dreams can be used to interpret earlier ones. Both of these points are emphasized in recent studies of the dream state. In common with all these early cultures and religions, Mohammedanism recognized the divine source of certain dreams, and the use of ritual to induce them and of holy prophets to interpret them. The Mohammedans, however, were especially insistent that some dreams have a purely physiological origin, such as those provoked by wine or salty food, while others have divine significance. They also recognized that dreams are symbolic, and that the same symbol could mean different things to different people depending on their character and age— for instance, the dream of having one’s hands tied signified final damnation for an evil man, but aversion from sin for a just man.The Greeks borrowed the practice of incubation from the Egyptians and Babylonians, and it is said that the cult of Aesculapius had over three hundred centers devoted to temple sleep.Typically, the patient was anointed with purifying oils, then sleep was induced by drugs, potions, poor ventilation, or hypnosis. The priest or oracle then “interpreted” the individual’s dreams and administered the therapy supposedly prescribed in them. This approach was first used for the cure of sterility, but was later applied to other disorders, including the use of suggestion and autosuggestion in the removal of apparently hysterical symptoms. Early Christianity adopted much of this mystique, with saints replacing priests, prayer replacing the Aescula- pian rituals, and a broader concept of divine inspiration replacing the emphasis on dream inspiration. It is interesting, however, that inspiration continued to be associated with healing in certain sacred places such as Lourdes—and sleeping in church after fasting was practiced for many centuries.Characteristically, the Greek philosophers introduced a rational approach to dreams and attempted to divorce them from their aura of mystery and magic (oneiromancy). Heraclitus viewed them as a carry-over of the cares and intentions of waking life. Democritus explained them in terms of physical emanations from persons and objects which penetrate the body and enter the consciousness of the dreamer. Plato believed that some dreams are divinely inspired, but also anticipated the Freudian view that repressed impulses are released in sleep: “In all of us, even in good men, there is a lawless wild- beast nature which peers out in sleep.” Aristotle advanced the theory that dreams are a continuation of sense activity during sleep, especially when we are under emotional stress. Though he rejected the idea of prophetic dreams, he suggested that fantasies occurring in dreams appear so vivid and real that they may influence our waking behavior. This appears to be a recognition of the power of the unconscious.In the second century, Artemidorus drew upon Greek, Assyrian, and Egyptian sources in writing the most important dream “bible” of ancient times, the Oneirocritica. In contrast to the prevailing approach of today, he stressed the associations the dream evokes in the mind of the interpreter rather than in the mind of the dreamer. He was “modem,” however, in recognizing the importance of certain fundamental symbols, and in warning that each dream has to be interpreted in the context of the dreamer’s personality and the conditions under which it took place. He further recognized that recurrent dreams have particular significance for the individual, especially when they evoke intense emotion; and that wordplays and puns in dreams should be analyzed. He also anticipated Jung in making a distinction between “insomnium” dreams, which reflect the current state of the individual’s mind and body, and “som- nium” dreams, which arise from deeper, more mysterious sources and may predict future events.Both the Hindu and Buddhist religions held that dreams reflect the soul’s experiences as it wanders from the body during sleep. The Chinese explained not only dreams but trances, fits, and visions as separations of the soul from the body, and, as in Egypt, judges and other officials fasted and performed rituals in order to induce dreams that would guide them in their affairs. Though the older Indian philosophers adhered to the view that the soul leaves the body, the Yoga practitioners of more recent times believed that dreams represent the highest degree of self-knowledge, in which the illusions of waking life are eliminated and our innermost feelings and aspirations are revealed. This, too, was an anticipation of current Western thinking.The Middle Ages did little more than reiterate older themes with a religious and moral emphasis. Christian writers,influenced by biblical dreams, believed that some dreams are prophetic and divinely inspired, but had great difficulty separating the true from the false, the good from the wicked, and those due to deity from those due to digestion. Gregory of Nyssa (fourth century) held that an individual’s passions expressed themselves in dreams, and that his type of personality can be gauged from their content. (It has been suggested that gargoyles are demonic dream symbols representing the repressions of the time.) Thomas Aquinas distinguished between dreams as divine revelations, as demonic messages, and as reflections of the body or soul of the dreamer himself. Luther and Calvin were particularly troubled by the problem of distinguishing demonic messages from those of divine origin. Au- gustinian monks practiced “sensory deprivation” in order to obtain a vision. They fasted for seven days, then placed themselves upright in a coffin for two days, and, if they lived, related their prophetic visions. There is evidence, too, that medieval Europe used a wide variety of hallucinogenic drugs to induce fantasies.