 For Gersonides, the issues of prophecy, omniscience and providence are developed against the backdrop of astrological determinism. Like many thinkers of the late Middle Ages, Gersonides had to confront two opposing sets of traditions: on the one hand, attacks by religious authorities (e.g. Augustine’s attack in City of God; Maimonides’ letters) on the grounds that astrology compromised human free will; on the other hand, the wide scale acceptance of astrology from the 12th century on. In the 12th and 13th centuries, most Jewish and Christian philosophers supported natural astrology, the view that the celestial bodies affect sublunar life and existence to some extent at least. That the sun and moon both affect natural cycles and events on earth is unequivocal and represents a classic paradigm of natural astrology. The calculations of natural astrology overlapped those of astronomy, and could be utilized for practical purposes such as fixing the calendar. According to astrologers, each planet and sign of the zodiac has its own character, power and attributes. Inasmuch as the characters of the planets and the signs of the zodiac are opposed to each other, they are engaged in a perpetual power struggle. Thus the position of the planets and their interrelation with the signs of the zodiac, regulate the fate of both individuals and nations. Astrological predictions could apply, then to both individuals as well as to the history of Israel and its place in universal history.