Shared Musical Material.

The term "cyclic mass" refers to a mass in which all five movements have musical material in common. One of the earliest is the Missa Caput in which all movements are composed over the same section of chant—a long, rhapsodic passage on the word caput (head), the last word in the Holy Thursday chant Venit ad Petrum. The anonymous English composer of this work assigns the chant to the tenor part of each of the five movements, and further unifies the movements by beginning each of them with the same small melodic-rhythmic motif.

The Contratenor Bassus.

The Caput Mass also displays another technique that was more and more becoming the norm in all polyphonic composition: writing the fourth voice part below the tenor rather than above it, creating the contratenor bassus ("against the tenor...