Science blog

22 October 2020

In our Hebrew Manuscripts exhibition, "Tsurat ha-arets" by Abraham bar Hiyya

A manuscript page written in Hebrew including a geometric diagram of circles.
A page from "Tsurat ha-arets"

Our Hebrew manuscripts exhibition continues until next year. You might not expect it to have a whole section on science, the prize of which is the manuscript numbered Or 10721, a copy of Tsurat ha-arets ("Form of the Earth") by Abraham bar Hiyya, with some additional works. It is thought to have been transcribed in the 15th century by one Joseph ben Se’adyah Ibn Hayyim. It is fully digitised at

Or 10721 was purchased in 1924 by the British Museum Library from the Romanian-British Jewish scholar, and Chief Rabbi of the English Sephardic community, the Rev. Moses Gaster, as part of a large collection known as the "Gaster Manuscripts". Bar Hiyya (1070?-1136) lived in Barcelona during the period of Moorish rule in 11th-12th centuries and was considered the foremost scientific authority of any background in Spain at the time. He probably introduced Arabic algebra into Middle Ages Europe, and his work was key to Fibonacci's introduction of the Hindu-Arabic number system into Christian Medieval Europe, which allowed modern maths to begin there. He published the first general solution of quadratic equations and wrote the oldest known mathematical work on the Hebrew calendar. His book Hegyon ha-Nefesh is considered to be the oldest surviving book on philosophy in the Hebrew language. Outside his scholarly studies, he held the government legal position "sahib al-shurta" of the Taifa of Zaragoza, a kingdom of the era that ruled a large part of Eastern Spain.

Bar Hiyya was the first major figure of Jewish scholarship to use Hebrew rather than Judeo-Arabic for scientific works. He developed a new vocabulary for science in the language and translated many existing Arabic scientific works into Hebrew, to improve what he considered to be the very poor state of mathematical knowledge among Spanish and French Jews of the era.

Tsurat ha-arets is a treatise on cosmology and geography describing the Ptolomaic or Earth-centred view of the universe, generally accepted in Middle Ages Europe. It also describes the division of the known northern hemisphere into seven "climates", or regions divided by east-west lines of latitude.

An earlier post on our Collection Care blog has described the most recent conservation of the manuscript.

Further reading:

Medieval Jewish civilization : an encyclopedia / edited by Norman Roth. London : Routledge, 2017. Available electronically in British Library reading rooms as Non-Print Legal Deposit.