The prediction of future was widely spread in Byzantium, both among simple people, as well as among church hierarchs and statesmen. Out of the different techniques of predicting, only a part of them possessed Christian justification. The value and the consequences of prophecy depended on the method that had been chosen. The medieval scholars, being representatives of clergy, warned those willing to learn about future, that they exposed themselves to illusions and lures. The ancient divination (necromancy, ecstasy of oracles, forewarning dreams etc.) involved heathen rituals and beliefs; this is why Church condemned them as a worship of demons. The problem got more subtle, since Christian authors admitted that heathen oracles sometimes gave true predictions (the Sibyl’s prophecies about Christ). In the Byzantine historiography, the occult practices were associated with evil rulers, heretics and heathens. The Paschal Chronicle called Zoroaster the inventor of magic and astrology. Prophet Mohamed was, according to Archbishop Macarius Melissenos, “very somnambulistic”, “mad, cunning”, “seized by epilepsy”. The Suidas lexicon listed the varieties of divination and called them diabolic prophecies: they seldom become true; the obscure assertions hide the ignorance of demons. Nicephorus Gregoras proved more tolerant towards oracles: no one knows their origin, they sometimes come from the good powers, sometimes – from the evil ones; they become false when people are impatient and interpret them for their own benefit. They frequently used to address astrology in order to solve political and military dilemmas. Consulting the stars disputed God’s sovereignty and omniscience, it undermined the human freedom (hence, our responsibility). St. Gregory of Nyssa reasoned that stars have their own motion and don’t depend on earthly things. In Codex Justinianus, astrology was considered a crime, like preparing poisons. Although an expert in astrology, Michael Psellos declared: “I’m not sure that our deeds could somehow be influenced by the movement of stars”. Nicetas Choniates blamed “the gossipers-astrologers”, “most evil deceivers”, “under the pretext of astronomy, they practised magic and other diabolic deceits”. Although saints received revelations in dreams and in visions, these could lead them into error; if they proved true, they would become a trap that could lead to the sin of haughtiness. Saints Anthony, Basil the Great and John Climax explained that demons are immaterial creatures and learn about many things before us; afterwards they announce us as if these were prophecies. The great spiritual confessors advised Christians not search to predict future, because it needed much discrimination and experience in order to avoid being tricked by demons. St. Isaac the Syrian cited the case of a saint who had received the gift of prophecy, but asked Lord to take it away from him. There were plenty of deceivers who exploited for their own interests the sovereigns’ curiosity. Flattering courtiers pretended that trivial happenings announced emperors about great successes. Michael Psellos and Georgios Pachymeres mocked at those haughty monks who designated beforetime the length of ruling and that of life for sovereigns. Emperor Michael VIII Paleologus hunted for those persons who dared consult forbidden books, where the future rulers of the state were listed. Although condemned by authorities, divination and astrology survived along the entire history of Byzantium. Some scholars blamed them, others practised them competently. The controversies around predictions were due to their pagan origin, to the obscurity of the super-sensorial experiences, to the goals promoted by their means.