Before and after John of Garland: The concept of directed dyadic progression and its prehistory

This article examines aspects of medieval polyphonic theory in numerous music-theoretical and pedagogical writings, from the ninth- or tenth-century Musica enchiriadis to several short anonymous texts composed around 1300, in order to show that the historically significant doctrine of directed dyadic progression (often called "interval progression") is not yet attested in any of them. In the process I devote considerable attention to the seminal contributions of the mid-thirteenth-century treatise De mensurabili musica, traditionally attributed to John of Garland, and to the more directly and persistently influential version thereof promulgated around 1280 by Franco of Cologne. This investigation supports my hypothesis, advanced elsewhere, that it was the recovery and dissemination, in the second half of the thirteenth century, of the Aristotelian theory of natural motion that, by providing an appropriate conceptual framework and vocabulary, made possible the emergence in music-theoretical discourse, beginning with Marchetto of Padua (Lucidarium, 1317/1318), of the concept of the directed dyadic progression, the historical precursor of our concept of harmonic progression