What did medieval readers take to be “Al-Ḥajjāj's version” of Euclid's Elements? The evidence of MS Paris, BnF, héb. 1011

The aim of this paper is to shed light on the transmission of Euclid's Elements in the Middle Ages, and in particular of an Arabic version of this work, which medieval sources attribute to al-Ḥajjāj ibn Yūsuf ibn Maṭar. I examine some medieval reports that explicitly ascribe certain textual variants and diagrams to this “Ḥajjāj-version.” These reports concern Books II–V and VII–X. I compare them to a medieval Hebrew version of the Elements, a single copy of which is extant in MS Paris, BnF, héb. 1011. The comparison reveals that no fewer than 14 and as many as 16 such reports conform to the Hebrew version. On the basis of these results, I argue that the circulation of a single complete version of the Elements widely recognized by medieval readers to be authored by al-Ḥajjāj, and one which perhaps was indeed his work, was not a myth.