Cantus Firmus

A cantus firmus is a preexistent melody that forms the basis of a larger musical work. Source melodies in the cantus firmus tradition have generally been selected from the vast corpus of plainchant, but secular tunes also provide a supply of monophony for use. The term is synonymous with cantus prius factus, canto fermo, and fester Gesang. Polyphonic settings of a cantus firmus may augment appropriate liturgies or may be found in other contexts. The foundational melodies sometimes signal extramusical or allegorical meaning when cast alongside other texts. In pedagogical contexts, cantus firmi appear as a fund of fixed musical subjects for teaching oral or written counterpoint. The first exercises in counterpoint against a cantus firmus may be found as early as the 10th century, when a note-against-note style prevailed. By the 12th century, and certainly in polyphony emanating from Notre Dame in Paris, florid counterpoint over a plainchant cantus firmus may be witnessed. As discant voices were added above a fixed song, the preexisting melodies became rhythmicized for the sake of coordination. In the 14th century, composers of motets subjected cantus firmi to isoperiodic treatment, abstractly manipulating them into repeating rhythmic and melodic cells. A heyday for settings of cantus firmus can be seen in the 15th century with the proliferation of Mass Ordinaries based on a variety of melodies. Transformations of preexistent song are taken to greater lengths with experiments in ornamentation, fragmentation, transposition, migration, retrograde, and inversion. Polyphonic mass traditions based on the Caput melisma and the L’Homme armé song famously emerge in this context. Although the most familiar and frequently studied examples of cantus firmus technique occur in sacred Latin works, the technique was adapted for polyphonic works in other languages, notably German chorale settings by Lutheran composers. Cantus firmi also undergird numerous secular genres, including the French-texted chanson rustique and combinative chanson as well as the German Tenorlied. Among instrumental works using cantus firmus technique, the most obvious examples are compositions for organ based on liturgical melodies, which have formed a central part of the instrument’s repertoire from the 16th century to the present day. However, cantus firmus techniques also featured in works for instrumental ensemble, including the famous In nomine fantasia. Since 1600, the use of a cantus firmus (especially in long note values) has typically been regarded a historicist gesture, serving as a religious topos or referring to specific techniques from medieval and Renaissance music.