L'homme armé
Prolation canons are among the most difficult canons to write, and are relatively rare in the repertory, though they are most common in the early Renaissance and from the 20th century to the present. Examples of prolation canons from the Renaissance include "Le Ray Au Soleyl" by Johannes Ciconia (late 14th century); the entire "Missa prolationum" by Johannes Ockeghem (mid-15th century), in which each separate section of the mass explores a different prolation (or different gap between entries and relative speed of each voice); the Agnus Dei from the "Missa L'homme armé super voces musicales" by Josquin des Prez (late 15th century); and the Agnus Dei from the "Missa L'homme armé" by Pierre de la Rue (early 16th century). Johann Sebastian Bach is known for his "Canon a 4 per Augmentationem et Diminutionem", the last in a set of 14 canons written as an appendix to the "Goldberg Variations". In the 20th century, one such canon is the "Cantus in Memoriam Benjamin Britten" by Arvo Pärt (1976). Additionally, Larry Polansky has written numerous four-voice prolation canons whose melodies are permutations of a limited number of elements, and Mark Alburger, in "Immortality" from "San Rafael News", directly maps a new melody into the framework of the aforementioned Josquin. A particularly striking example of prolation canon occurs twice in the opening movement of Shostakovich's Symphony No. 15 (1971), first in the strings (Rehearsal Figure 27) and later in the woodwind at Rehearsal Figure 47. A more recent example of a prolation canon in contemporary music is "rindenmotette" (2011) by Austrian composer Klaus Lang.