Signposting mutation in some fourteenth- and fifteenth-century music theory treatises

ABSTRACT The foundation of the solmisation system, attributed to Guido d'Arezzo, is based upon the application of the syllables ut, re, mi, fa, sol, la, to the musical notes C D E F G A. Later, this system was expanded to incorporate a series of overlapping hexachords made up of these six syllables. These overlapping hexachords could allow a singer to move seamlessly across the regular musical space (the gamut) using only the six syllables (voces) via ‘mutations’. Even though the extent to which this system underpinned diatonic conceptions of musical space is being reconsidered, it seems clear that, at least for some musicians, it played an integral part in music education. Although many theorists discussed the process of hexachordal mutation in their treatises, the approaches towards its exemplification and demonstration were far from uniform, given its conceptual rather than notated function. Johannes Tinctoris's Expositio manus (c.1472) includes a number of musical examples showing hexachordal mutation. His examples, rather unusually, include syllabic annotations to label the points of mutation within the musical notation, a practice that is almost without precedent. This article takes Tinctoris's treatise as a point of departure and compares the approaches taken towards the exemplification of hexachordal mutation in some theoretical texts from the fourteenth and fifteenth centuries, tracking the influence of their approaches forward into the sixteenth century. It considers what some different approaches can tell us about the conceptual function of the hexachord in pedagogy, and what the motives might have been for adopting specific exemplification practices.