This book aims to show how Ibn al-Bannāʾ’s famous Arabic text on arithmetic and algebra Talkhīṣ Aḥmāl al-Ḥisāb (A Summary of the operations of Calculation) was transmitted into Hebrew by the polymath Isaac Ibn al-Aḥdab, resulting in the extensive text The Epistle of the Number. This book presents the first edition of The Epistle of the Number, which was composed in Syracuse, Sicily, at the end of the 14th century. It also depicts the fascinating figure of Isaac Ibn al-Aḥdab: astronomer, mathematician, poet, exegete and ‘calendar-man’ – shedding new light on his persona and intellectual activity.

The Hebrew Epistle plays a pivotal role in the history of medieval Hebrew mathematics because it is the first known Hebrew treatise which includes extensive algebraic theories and procedures. It is also the first (and last) known Hebrew version of Talkhīṣ Aḥmāl al-Ḥisāb. The Hebrew Epistle exposes novel mathematical vocabulary and enhances our understanding of the linguistic mechanisms which helped create scientific vocabulary in medieval Hebrew. The Epistle of the Number is a palpable witness to the transmission of Arabic science to Jewish circles in Christian Syracuse at the end of the 14th century, reflecting the scientific activity of the Jews there, of which still relatively little is known. This book will be of interest to scholars in the fields of Jewish Studies, Hebrew philology, medieval studies, mathematics, history of science, and, in particular, history of medieval Hebrew and Arabic mathematics.

Ilana Wartenberg studied mathematics, linguistics, and history and philosophy of science at Tel Aviv University and at Université de Paris VII. She is currently a research fellow in the department of Hebrew and Jewish Studies at University College London.

Cover: Detail from Cambridge University Library MS Heb. Add. 492.1, fol. 26v.