Sefer ha-Tequfah: An unknown treatise on anniversary horoscopy by Abraham Ibn Ezra

The full text of a hitherto unnoticed treatise on anniversary horoscopy authored by Abraham Ibn Ezra, Sefer ha-Tequfah (Book of the revolution), has been identified. Although the author's name is not recorded in any of the surviving copies, cogent reasons establish Ibn Ezra's authorship: the Hebrew astrological nomenclature, style, content and structure, links to other parts of Ibn Ezra's oeuvre, and the discovery that Sefer ha-Tequfah is the Hebrew original of Liber revolucionum, a Latin astrological text on continuous horoscopy. This brief study demonstrates Ibn Ezra's authorship and presents several excerpts from the Hebrew text, accompanied by their English translation and their Latin counterparts in Liber revolucionum.