AbstractThis survey of classical astrology is in three parts: a) a summary of its rich and eventful history from the Babylonians to the Renaissance; b) the methods of calculation which remained the same throughout the period, based on the planets, the zodiac and the “twelve houses”; c) an analysis of astrological thought, which is quite different from any modern approach; providing a rigid interpretation of the universe, it granted confort and security. It presents a curious combination of religion and science: the physics is the one forwarded by the stoïcs, with an equal balance of the four elements, and the microcosmic economy within the soul representing the macrocosmic one; but such a determinism is in contradiction with the Stoics' sense of responsability which presupposes free