The two chief forms of Catholic Public Prayer are the Mass (Eucharistic Liturgy) and the Divine Office (Liturgy of the Hours). Both consist of silent and vocal prayers, and from the beginning of Christian services, many of the vocal prayers have been chanted or sung. Over time the chants, songs, and hymns associated with these liturgies, especially the Mass, evolved to incorporate sophisticated musical arrangements.
As a result of Vatican II, the Liturgies associated with both the Divine Office and Roman Rite Mass under underwent a dramatic revision. One of the most significant changes was the use of the vernacular instead of Latin. Since almost the entire musical repertoire of the Catholic Church was rooted in Latin, this change, in one swoop, radically altered a 2000 year old musical tradition. Many hymns, sequences, and prayers that had been sung for a millennium have fallen into disuse.
In order to understand the contribution of the Church to the history of Western Music, therefore, it is helpful to at least understand the basic components of the Divine Liturgy and Traditional Latin Mass these were the rites on which the Western musical heritage was built.
A Missa Cantata is a Choral composition that sets the invariable (ordinary) portions of the Mass to music. Sung masses were the principle form of sacred compositions during the Middle Ages. The earliest Missa were sung a cappella or accompanied by an organ, but by the 18th century masses were sometimes written for an orchestra intended for performance rather than worship.
Parts of the ‘Ordinary’ of the Mass typically set forth in Music were:
Commonly used Gregorian chants the ordinary of the mass for these sung masses are collected in a book called the Kyriale.
Variable parts were specific to mass type or liturgical season could also be set to music:
Other parts of the Mass had to be chanted or sung by a priest, deacon, or lector, not a choir.
Besides these parts of a sung mass, hymns were also also frequently sung during the Offertory and Communion services.
Masses were the most common type of Sacred composition in the early years of Polyphony, but variable parts of the mass included hymns or sequences that could be sung for occasions other than mass. Eventually other types of composition began to be composed and sung outside the context of the Mass.
Books used for Musical Masses include Kyriale, Liber Usualis, Graduale Romanum