Vestiges of the Isorhythmic Tradition in Mass and Motet, ca. 1450-1475

The article examines a small group of masses and motets by Du Fay, Busnoys, Regis, and Josquin that may date from the third quarter of the fifteenth century. Each piece reflects the composer's interest in preserving various aspects of the isorhythmic tradition. One such aspect is a compositional technique referred to as modus disposition, the control of a piece by making the total duration of a section divisible by two or three breves, depending on whether imperfect or perfect modus is in control. Another feature that is a vestige of the isorhythmic tradition is the planning of a piece so that precise ratios are created between various sectional durations within the piece; several important pieces displaying such ratios can be thought of as manifesting number disposition rather than number symbolism. On the basis of similarities in compositional technique and unusual mensural features, the argument is made that Du Fay's Missa Se la face ay pale may have inspired Busnoys' Missa L'homme armé (as well as several motets by Busnoys and Regis), and that Busnoys' mass in turn may have inspired sections of the Missa Di dadi and Missa L'ami baudichon by Josquin. Issues surrounding Josquin's Illibata Dei virgo nutrix are considered, particularly the notion that the motet transforms stylistic norms that were associated with the isorhythmic tradition, as mediated by Busnoys' In Hydraulis. The use of perfect modus in Illibata seems to be a further reference to the isorhythmic tradition. In an attempt to assess the unique stylistic properties of Illibata, relationships between it and other motets by Josquin from the 1470s are explored.