(fl late 13th century and early 14th). French Benedictine music theorist. He was a monk of St Denis: Ulysse Chevalier falsely claimed that he was Guy de Chartres, Abbot of St Denis between 1294 and 1310 (Répertoire des sources historiques du Moyen Age: bio-bibliographie, Paris, 1877–88, 2/1905–7, i, p.2013), but he cannot be identified among the many monks named Guy in the obit lists of St Denis (ed. C. Samaran in Bibliothèque de l'Ecole des chartes, civ, 1943, p.49). The sole surviving copy of his treatise (GB-Lbl Harl.281, ff.58v–96) concludes ‘Here ends the treatise on the tones compiled by brother Guido, monk of the monastery of St Denis in France’; this information is confirmed by an acrostic of the initial letters of the introduction and the four sections of the treatise, which yields the name ‘Guido’ (a similar procedure may be observed in the seven sections of the Speculum musice of Guy's contemporary Jacobus of Liège).
Guy's treatise comprises two sections. The first is theoretical, and deals with the Gregorian psalm tones, consonances, modes etc. The second section is practical, and concerns the performance of the psalms and the use of the neuma (melismas that might be added at the ends of certain chants). It concludes with a tonary corresponding with the antiphoner and gradual in use at St Denis. Guy quoted a hymn from the Office of St Louis; Louis was canonized in 1297 and the Office composed in 1299 (this Office followed the Paris use, however, and according to Guy, was not sung at St Denis). He also mentioned an unknown chant for Corpus Christi. This festival was introduced at Paris in 1318, and slightly earlier at St Denis since Cluny introduced it in 1315; the treatise must therefore have been compiled before Paris adopted the Corpus Christi Office commonly attributed to St Thomas Aquinas (i.e. in the period between 1315 and 1318).
The sources of the treatise include Plato, Aristotle, Boethius, the Micrologus of Guido of Arezzo, Honorius of Autun, Guillaume d'Auxerre on the neuma, the Dialogus of Pseudo-Odo (see Odo) and the treatises on plainchant by Petrus de Cruce (‘qui fuit optimus cantor’) and, in particular, Johannes de Garlandia. Guy's quotations from the latter enabled Reimer to identify the authentic version of Johannes's treatise.
EitnerQ
FétisB
M. Huglo: Les tonaires: inventaire, analyse, comparaison (Paris, 1971), 337–8
E. Reimer, ed.: Johannes de Garlandia: De mensurabili musica (Wiesbaden, 1972), 6–10
A.W. Robertson: The Service Books of the Royal Abbey of Saint-Denis: Images of Ritual and Music in the Middle Ages (Oxford, 1991), 113–29, 334–5
MICHEL HUGLO