cantus firmus mass

Cantus firmus means 'Fixed Song'.  The cantus firmus mass is a mass in which every section was composed using the same pre-existing meody as the contrapuntal foundation.  The cantus firmus was often derived from a chant or a popular song.  This form was developed by the composers of the Burgundian School.  Before this time, and with the rare exception of Guillaume de Machaut, the movements were composed separately.  The cantus firmus in each movement unifies the movements while still allowing a large amount of harmonic and melodic individuality.

In the early masses, the cantus firmus was found in the tenor, often written in long notes and varied isorhythmically.  It might even be inverted or reversed, as Dufay did in his Mass L'homme armé.  L'homme armé was a popular fifteenth century French song.  It was used as a cantus firmus by many composers in the fifteenth and sixteenth centuries.  Josquin even spelt sentences out with solfege syllables to build a cantus firmus.

Some other examples of Cantus firmus masses are the Missa Caput masses by Dufay, Ockegam and Obrecht; the Missa Alma redemptoris mater by Leonel Power; the Missa Fors seulement, and the Missa se la face ay pale by Guillaume Du Fay.