Guy of Saint-Denis, Tractatus de tonis Tractatus de tonis

The Tractatus de tonis of Guy of Saint-Denis (written ca. 1300-10) differs from other treatises on plainchant in the depth of its analysis of the various tones into which chant was traditionally classified. Guy's treatise presents itself as a synthetic overview of both the theory and practice of plainchant in a way that combines the practical reflection of Guido of Arezzo with ideas of more Aristoteleian inspired theorists such as Johannes de Grocheio and Peter of Auvergne. The Tractatus de tonis of Guy of Saint-Denisoffers original reflection on the nature and emotional power of the tones into whichplainchant is classified.