Mathematical Philology in the Treatise on Double False Position in an Arabic Manuscript at Columbia University

This article examines an Arabic mathematical manuscript at Columbia University’s Rare Book and Manuscript Library (or. 45), focusing on a previously unpublished set of texts: the treatise on the mathematical method known as Double False Position, as supplemented by Jābir ibn Ibrāhīm al-Ṣābī (tenth century?), and the commentaries by Aḥmad ibn al-Sarī (d. 548/1153–4) and Saʿd al-Dīn Asʿad ibn Saʿīd al-Hamadhānī (12th/13th century?), the latter previously unnoticed. The article sketches the contents of the manuscript, then offers an editio princeps, translation, and analysis of the treatise. It then considers how the Swiss historian of mathematics Heinrich Suter (1848–1922) read Jābir’s treatise (as contained in a different manuscript) before concluding with my own proposal for how to go about reading this mathematical text: as a witness of multiple stages of a complex textual tradition of teaching, extending, and rethinking mathematics—that is, we should read it philologically.