Abu Ma'shar's famous Great Introduction to traditional astrology was a major influence on medieval astrologers through its Latin versions, and is available and explained to modern audiences in this new translation from the Arabic original. Written in the early 800s during the Golden Age of the 'Abbasid Caliphate in Baghdad, the Great Introduction falls into two parts. Books I-IV present a theory of astrology and its primary concepts in the language of Aristotelian philosophy, including a lengthy defense of astrology. Books V-VIII contain numerous lists and descriptions of sign categories, planetary conditions, and planetary configurations. Book VII describes how to judge elemental combinations in planetary conjunctions, and Book VIII contains Abu Ma'shar's classic list of Lots and how to interpret them. The Great Introduction is a landmark in astrological history, and is a must-have for practitioners and historians.