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Psychomanteums were ancient Greek oracles of the dead where seekers could consult the spirits of the deceased. After fasting and certain other preparatory rituals, a vision of the departed was evoked by the seeker’s staring into a pool or pan of water (a technique similar to the practice of “crystal gazing”). Alternatively, seekers sometimes attempted to contact the dead via dreams, an endeavor clearly related to other types of dream incubation, in which dreams were sought for specific purposes—healing, financial guidance, general advice, divination, and so forth. Dream incubation was extremely popular in the ancient world and was a major phenomenon in societies as diverse as ancient Mesopotamia, Egypt, Greece, and Rome. In the Hellenistic period, the principal dream incubation temples were the healing temples of Aesculapius. The Hellenistic fascination with dreams made them an obvious medium for attempting to contact the departed.