Snow on the Mountains: Number in Grocheio in the Thirteenth Century

Grocheio's treatise Ars Musice occupies the central folios in the manuscript Harley 281 (GB-Lbl Harl.281), principally copied by a single scribe around 1300 AD. It is replete with numbers and Hindu-Arabic numerals and thereby is totally distinguished from all the other treatises on music theory in the manuscript. Grocheio's work, apparently not well known in medieval times, much better known now since the work of Rohloff, Seay and Page inter alia, is preserved in only two manuscripts (the Harley and Darmstadt D-DS 2663). In this paper we discuss Grocheoi's surprisingly frequent use of number, and the role of the numerals in the manuscript in their contexts. We also investigate what evidence this provides the width of Grocheio's knowledge of mathematics and science.