Chapter 6 begins in the same geographical area as chapter 5, examining the changes in music and especially in musical notation in the fourteenth century that are termed the Ars Nova. The careers of the musicians Philippe de Vitry and Guillaume de Machaut - both encompassing roles in royal or noble administration, and ecclesiastical positions - contrast markedly with the lives of the thirteenth-century trouvères. New approaches to musical notation both responded to and facilitated greater rhythmic complexity in both Latin polyphony and vernacular song, and these elements were elaborated even further at the end of the century by composers of the Ars Subtilior. The technique of isorhythm offered a way for polyphonic pieces to be structured along primarily musical lines, and composers made the most of the opportunities it provided to create subtle and sophisticated forms. Against a backdrop of climate emergency and a great pandemic (the Black Death), political and religious upheaval in the form of the Hundred Years’ War and the Avignon papacy, musicians used satire and allegory to shine a critical light on their society and its leaders.

This chapter introduces mensural notation and shows how changes of practice affect musical style during the Renaissance, mirroring the approach in the previous chapters in the domain of pitch. Here again, two crucial changes are observable, roughly contemporary with those observed in Chapter 5: the first is the gradual abandonment of major prolation (c. 1440) as the predominant mensuration in favour of perfect tempus, and the alternation of tempus perfectum and tempus imperfectum (with minor prolation) as a structural feature in larger-scale works; the second is the adoption of tempus imperfectum as the standard mensural sign during the final quarter of the fifteenth century, after which the notational subtleties associated with the system of ‘four prolations’ gradually fell out of use. But this chapter also demonstrates the great elegance of the mensural system, showing its flexibility and economical presentation of situations of considerable rhythmic intricacy, which has an aesthetic quality all of its own. In many cases, the conception of the individual work is grounded as much in its notation as in the sounding result.