The heptachordal basis of hexachordal theory: on the semiotics of musical notation in the Middle Ages

Abstract

ABSTRACTBy all appearances, the advent of a full-fledged hexachordal system in the late thirteenth century marked the culmination of a radical reconceptualisation of diatonic space that had begun over two centuries earlier with Guido of Arezzo's introduction of the syllables ut re mi fa sol la as an aid to sight-singing. An early witness of the new diatonic configuration is Johannes de Garlandia's Introductio musicae planae (c.1275), which presents the three proprietates per b quadro, per natura and per b molle as a fundamental articulation of the gamut that is necessary for conveying the intervallic distances between the diatonic pitches.A contextual evaluation of the theory of the proprietates, however, indicates that the hexachordal parsing of the gamut was not meant to establish the major sixth as the regulative paradigm of diatonic space (i.e. as a normative scale), but was rather in line with the earlier understanding of the ut-la syllables as an optional aid for singing. The development of hexachordal theory was in fact an implicit confirmation of the heptachordal structure of the gamut that had been in place since around the year 1000 (and arguably earlier), when the cycle of seven A–G letters was first used to label the constituent pitches of the octave.