Nicolas BELL, Cambridge The role of the music scribe differs in many fundamental respects from that of the text scribe. The relation between written neume and sounding note is far more complex and less direct than between written text and spoken word. In the thirteenth century we can observe for the first time a direct and reciprocal link between the roles of music scribe and music theorist, in particular as they experimented with new ways of representing rhythms. Codex IX of the Monasterio de Las Huelgas in Burgos presents a far wider range of musical genres than any other source of thirteenth-century music, and predominantly uses a fixed set of signs. By observing the varied contexts in which these signs occur, we may discern the intellectual processes of the scribe in translating the diverse notations of his numerous exemplars into a form closer to his idea of how the pieces should be performed. With varying degrees of success, the scribe imposes rhythmic notation onto pieces previously written without it, and changes rhythms where they seem awkward to him. An empirical analysis of representative pieces will reveal some of the problems faced in approaching the different chronological and stylistic strata of the codex.