From the Middle Ages until the present, the development of astrology among Jews was associated mainly with the name of Abraham Ibn Ezra (1089-1167). His scientific corpus deals with mathematics, astronomy, scientific instruments and tools, and the Jewish calendar; but especially with astrology. This volume is the first product of a larger enterprise-a scientific edition of all twelve Ibn Ezra's astrological treatises-and offers a critical Hebrew text of the two versions of Ibn Ezra's Sefer ha-Te'amim, the Book of Reasons, accompanied by an annotated translation and commentary. The two treatises presented here were designed by Ibn Ezra to offer "e;reasons"e;, "e;explanations"e;, or "e;meanings"e; of the raw astrological concepts formulated in the introduction to astrology that Ibn Ezra entitled Reshit Hokhmah (Beginning of Wisdom).