Jewish Land Surveyors in Eleventh-Century Catalonia and the Introduction of Arabic Science to Europe

In early twelfth-century Barcelona, Abraham bar Ḥiyya (c. 1070–1145) composed the first Hebrew book on mathematics and geometry dedicated to land surveying. This book eventually bolstered the use of Hindu-Arabic numerals in Europe. The present article seeks to identify the audiences of bar Ḥiyya’s book and to explore the role of Jewish land surveyors in the shift from Roman to Arabic knowledge in eleventh-century Catalonia. Using the work of one such Jewish land surveyor in the year 1000 and testimonies of Jewish use of linear measurements in other practical documents, this study attempts to narrow the gap between theoretical and practical knowledge. The conclusions of this paper are that Catalonian Jews buying and selling land tended to prefer measurements, a religiously neutral unit, over identification of the adjacent borders of fields—a process that was accompanied by distinctly Christian rituals. This made them natural candidates to serve as land surveyors. Furthermore, even before the first Latin (or Hebrew) translations of Arabic scientific writings, this tendency, combined with their ties to Andalusia, positioned them as agents of change, leading the way for the introduction of Arabic knowledge in their region and beyond.