Arrangement for: Piano

The Montpellier Codex (Montpellier, Bibliothèque Inter-Universitaire, Section Médecine, H196) is an important source of 13th-century French polyphony. The Codex contains 336 polyphonic works probably composed c. 1250–1300, and was likely compiled c. 1300. It is believed to originate from Paris. It was discovered by musicologist Edmond de Coussemaker in c. 1852.

The Montpellier Codex can be roughly divided into 8 fascicles, each of which contain discrete genres of music. The format of the Codex is as follows:

There are also supplements added to fascicles 3, 5, and 7. Because of the different systems of notation used in fascicles 2-6 and fascicles 7-8, the Montpellier Codex has become a crucial source for the chronology of styles of French medieval polyphony.

The Montpellier Codex is a critical source for what are known as "Pre-Franconian" and "Franconian" motets, after Franco of Cologne. While the music in the Codex is anonymous, a number of attributions can be made, either because of concordances in other manuscripts or on the basis of stylistic similarity, to Pérotin (from fascicle 1), Petrus de Cruce, Adam de la Halle, Guillaume d'Auvergne, and Philippe le Chancelier. Many of the cantus firmi are taken from the chants of Notre Dame. While fascicle 1 consists of sacred polyphony, mostly from the Notre Dame school, the largest body of music in the Codex is the collection of French courtly love motets.

Previously, the motets in the collection were not considered to be isorhythmic, as it was felt that the first isorhythmic motets—those of Philippe de Vitry—were not to be composed until the first decades of the 14th century. Recently, however, Michael Lanford has noted that "of the 148 double and triple motets in fascicles two through five of the Montpellier Codex, 114 have repeating colores." After analyzing several motets, he also demonstrates that "each of Richard Hoppin's 'three isorhythmic procedures' which inform 'future developments of the form' can be found in select tenors from the Old Corpus [of the Montpellier Codex], often in ways that demonstrate resourceful approaches to managing the rhythmic modes." For these reasons, Lanford contends that "by glossing over the presence of isorhythmic techniques in thirteenth-century motets, such as those found in fascicles two through five of the Montpellier Codex, scholars have thus limited the appellation of 'isorhythm' using criteria that is well-reasoned, yet perhaps unnecessarily restrictive."

One motet in the Codex was copied from a polyphonic composition by Willelmus de Winchecumbe (fl. 1270s).