 While this classification remained mostly unchallenged, there were some important dissenting voices (for an overview, see Dyer 2007). These disputes regarding the proper classification of music are important because they reflect underlying concerns with music’s nature and purposes. From the thirteenth century onwards, theorists and philosophers became more concerned with the practical and acoustic sides of music-making, and less with its theological implications. For instance, the English grammarian John of Garland (1195–1272) distinguishes between plainsong, mensural music, and instrumental music, and does so on the bases of historical and musicological differences between such repertoires (see Fubini 1991: 94).