UCL Discovery
UCL home » Library Services » Electronic resources » UCL Discovery

The problem of the date line in medieval Jewish sources

Stern, SD; (2017) The problem of the date line in medieval Jewish sources. In: Nha, I-S and Orchiston, W and Stephenson, FR, (eds.) The History of World Calendars and Calendar-making. Proceedings of the International Conference in Commemoration of the 600th Anniversary of the Birth of Kim Dam. (pp. 113-122). Yonsei University Press: Seoul, Korea. Green open access

[thumbnail of Ch 14 (Stern date line in Jewish sources 04).pdf]
Ch 14 (Stern date line in Jewish sources 04).pdf

Download (486kB) | Preview


The date line is an imaginary line on the Earth, running from north to south, which demarcates a change of the date for whoever crosses it. Its location is arbitrary and dependent on international consensus. The date line is not an objective reality, but an anomaly resulting from the globalization of the seven-day week and calendars. Medieval Jewish scholars were the first to conceive the date line and to discuss its location on the globe. The date line was first mentioned and discussed in Judah ha-Levi’s Kuzari (Spain, 1130‒1140); he located it at 90o east of Palestine. His argument was criticized in 1310 by Isaac Israeli (Toledo), in his calendar treatise Yesod Olam; Israeli rejected the concept of a date line, and proposed instead a geographical model for global time. This model, however, was upset by the later discovery of the New World. Consequently, in his astronomical work Neḥmad ve-Naim (1601‒ 1613), David Ganz (Prague) rejected Israeli’s theory, and left the problem of the date line unresolved. Non-Jewish scholars, in particular Christians, took much longer to address the problem of the date line. It was briefly mentioned for the first time by a Christian scientist, Nicole Oresme, in the fourteenth century; but it was not seriously discussed by Christians until much later, following the development of world circumnavigation and European colonization of America and the Pacific Ocean in the sixteenth and seventeenth centuries. In this paper, an attempt is made to explain why, in the Middle Ages, the date line remained a specifically Jewish concern. This may have reflected a Jewish interest in precise calendar reckoning and in theoretical legal problems, but was also related to an ideology that viewed time, and more particularly the weekly Sabbath, as an objective and global reality.

Type: Book chapter
Title: The problem of the date line in medieval Jewish sources
ISBN-13: 9788968501883
Open access status: An open access version is available from UCL Discovery
Language: English
Additional information: This version is the version of record. For information on re-use, please refer to the publisher’s terms and conditions.
Keywords: date line, Jewish, medieval, Christian, Judah ha-Levi
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL SLASH
UCL > Provost and Vice Provost Offices > UCL SLASH > Faculty of Arts and Humanities
UCL > Provost and Vice Provost Offices > UCL SLASH > Faculty of Arts and Humanities > Dept of Hebrew and Jewish Studies
URI: https://discovery.ucl.ac.uk/id/eprint/1569660
Downloads since deposit
Download activity - last month
Download activity - last 12 months
Downloads by country - last 12 months

Archive Staff Only

View Item View Item