Practices of Textual Changes in Medieval Mathematical Manuscripts

One of the well-known medieval mathematical treatises written in Hebrew is Rabbi Abrahambar Ḥiyya’s Ḥibbur ha-Meshiḥah ve-ha-Tishboret, composed between 1116 and 1145. The Ḥibbursurvives in (at least) eight manuscript copies, produced between the fourteenth and the sixteenthcenturies, as well as in a Latin translation titled Liber embadorum, made in 1145 by Plato of Tivoli.Of the latter, five extant copies from the fifteenth and the sixteenth centuries are known. While theLatin translation adheres to the general structure of the Ḥibbur, it also exhibits specific changesthat are indicative of the historical development of both the Hebrew and the Latin texts. By focusingexclusively on the extant manuscripts – rather than on any endeavor to (re)construct a history ofthe Urtext, whether in Hebrew or Latin – one can observe not only various omissions, comments,and notes added to the various copies, but also that such changes modify the character of the text,rendering it less or more practice- or theory-oriented.What do these additions and omissions reveal about how mathematical texts were regarded in thefourteenth to sixteenth centuries? Can we draw conclusions about how these texts were read, copiedand used? To answer these questions, this paper examines three sections of the Ḥibbur and Liberembadorum, all of which concern the study of the division of geometric figures. I argue that a refinedtypology of the additions, omissions, added notes, comments and diagrams can help us to see thesemanuscripts not as ‘copies’ of an ‘original text’, but as complex mathematical written artefacts intheir own right, each with unique characteristics.