Jean de Ockeghem and the Mensuration Canon

You could say the title of this blog reads like a mystery novel and in a way that is exactly what a mensuration canon is. More on that later. First I shall set the scene.

France, Flanders and the Netherlands  was home to several prominent composers in the second half of the fifteenth century. One of these was Jean de Ockeghem, one of the leading composers in the Renaissance period. He was born in approximately 1420 in Hainaut, North-eastern France and was a member of the Royal Chapel of Charles I, Duke of Bourbon, becoming a priest in about 1464. He followed in the footsteps of Du Fay, was a contemporary of Busnoys and produced a relatively small number of works despite his renown. He was revered for his masses whilst Busnoys was esteemed for his many chansons. Together they were acclaimed as “the most outstanding and most famous professors of the art of music” by Tinctoris.

Ockeghem wrote 13 masses, a Requiem Mass, 21 chansons and at least 5 motets. Many of his chansons, as well as Busnoys’s were extremely popular and appeared regularly in manuscripts in many other countries. At this time compositions were often rearranged, transcribed for instruments or used as the basis for other composers’ works.

As with Busnoys’s music, Ockeghem’s music featured a mixture of old and new styles. They retained the use of forms fixes, syncopated rhythms, dissonances and the use of thirds and sixths from the previous generation but introduced a more equal use of the different voice parts. They also began to use four voice parts: the cantus or superius, the altus, the tenor and the contratenor or bassus. They also made changes to the vocal ranges for each voice part. 

“Through these changes Ockeghem creates a fuller, darker texture than we find in Du Fay’s works.” A History of Western Music, 9^th Edition. (Burkholder, Grout and Palisca)

Ockeghem’s Missa Prolationum is a great example of this and he contrasts upper and lower voices in pairs as well as writing some sections as trios or duets. It is notated for two voices but sung in four parts. This image shows an example of the original score.

It uses the four prolations of mensural notation, these being either Major or Minor prolation in Perfect or Imperfect time, thus dictating the time signature each part should be sung in. Two parts coming from one notated line is called a canon and, depending on which prolation they are following; they sing the same melody at a different time. This is where we come back to the mystery I spoke of earlier. To quote my lecturer, it is “hidden in the same way as the perfect crime.” As the parts interweave at their differing speeds it is almost impossible to tell which voice is singing the melody as it is so cleverly written with mathematical precision. This is known as a mensuration canon; in fact, it is also a double canon as each of the originally notated two lines is sung in canon. Clever stuff indeed. These canons were greatly valued by musicians for being ingenious and extremely skilful and many enjoyed trying to solve the mystery from written scores for themselves. Here is a YouTube clip of the Missa Prolationum with the score. Embrace you inner Hercule Poirot and see if you can figure it out.