初期アッバース朝と歴史占星術

アブー・マアシャルの『宗教と王朝の書』について

抄録

Historical astrology is the branch of astrology that deals with political and religious history by using the conjunctions of the superior planets. This kind of astrology had been developed in Sasanian Persia on the basis of the Indian system of yuga.
The Book of Religions and Dynasties attributed to Abu Ma'šar (787-886 A. D.) is the most complete surviving work that gives us a systematic account of the full range and methodology of historical astrology. The most significant difference between The Book of Religions and Dynasties and other surviving texts concerning historical astrology attributed to Sasanian and early 'Abbasid astrologers, such as Zoroaster, Gamasb, Maša'allah, and al-Kindi, is that only the former attempts to explain philosophical and technical principles.
According to The Book of Religions and Dynasties, astrological interpretation is mainly based on four kinds of conjunction and four horoscopes. Out of the four conjunctions, three are those of Saturn and Jupiter, occurring every 20 years in each sign, every 240 years within the same triplicity, and every 960 years returning to the first sign, and one is that of Saturn and Mars every 30 years in the sign of Cancer. The basic horoscopes are set up for the vernal equinoxes in 571 A. D., i. e. the year of conjunction indicating the Religion, in 622 A. D., i. e. the year of Hegira, in 749 A. D., i. e. the year in which the shift of rulership to as-Sawad (the 'Abbasids), and in 809 A. D., the year in which the sign of conjunction moved from a watery triplicity to a fiery one.
Historical astrology was introduced from the Sasanian tradition by al-Mansur (ca. 713-775) as one of the policies by which he could lay the solid foundation of the newborn dynasty, and it was used most effectively among the early 'Abbasids. The Book of Religions and Dynasties will cast a new light on the future studies of Sasanian and early 'Abbasid dynasties.