The Ordinary of the Mass was a principal genre in the Renaissance, and most Renaissance composers gave it considerable attention. The masses of William Byrd are among the most distinguished of the genre. The first polyphonic mass I ever sang was William Byrd's Mass for Five Voices. The first polyphonic mass I ever sang with the St. Ann Choir--which I now direct--was Byrd's Mass for Three Voices. This choir has sung the Mass for Four Voices at least twice a year for the last thirty-five years and the others occasionally. Having sung the Four-Voice Mass most frequently, I have always been surprised when singing one of the others to notice the close resemblances; I have often thought, "Why, this is the same mass with different notes." While this may be a slight exaggeration, it points to the unique position of the masses among Byrd's works in striking contrast with the works of the other prominent Renaissance composers. While Palestrina wrote over a hundred, Lasso nearly eighty, Victoria nearly twenty, and Josquin at least fifteen, Byrd wrote only three: simply one for each number of voices, three, four, and five. Why? Why not the amazing variety of the continental composers? What difference does it make? What sense does the difference make?
The Renaissance Mass Ordinary is a paradoxical genre; it is comprised of diverse texts bound by a single musical style. This was not the case in the Middle Ages. At that time, each piece of the ordinary was a separate liturgical genre: litanies--Kyrie and Agnus Dei, hymns--Gloria and Sanctus, and profession of belief--Credo. And each of these genres had its own musical style. These movements, whose texts remained constant from service to service, were most likely to have been set to polyphonic music for practical reasons: the settings could be used on any day in contrast with the Propers of the Mass, which could be sung on only one or at most a few days of the year. Yet, there was little integration among the parts of the ordinary when they were set to polyphonic music. Even the mass of Guillaume de Machaut was probably compiled from separately existing movements; some of its movements were based upon chant melodies and some were not, and those that were used different chants for each movement.
In the Renaissance, in contrast, there was a sense of artistic integration among those movements distinguished by polyphonic setting. The five movements of the ordinary were now composed as the pillars of the whole service, integrating and ordering the entire liturgy. They were in a consistent style from movement to movement, despite the diversity of their texts. Being all by a single composer, their consistent style created a kind of rondo-like musical structure in alternation with the other elements of the service, which were mostly chants in diverse styles and modes, written at varying times over the whole history. Since these mass compositions were numerous--Palestrina alone wrote 103--and were all on the same set of texts, there had to be a principle of differentiation. To imagine the difficulty for a composer setting about to write his hundredth mass upon the same texts, yet composing something original that had not been done in any of the previous settings, is to realize the necessity of a principle of differentiation between such numerous masses. How could each of these masses have a unique style and expression? The principle of differentiation was the use of borrowed material: each mass was based upon musical material--chants or polyphonic pieces, sacred or secular--that had its source outside the mass itself, ensuring that the mass based upon it sounded fundamentally different from others based upon other borrowed materials.
There were striking differences in this use of borrowed materials between the fifteenth and the sixteenth centuries, what they borrowed and why they borrowed it. These differences relate to a difference between the aesthetics of the two centuries, a difference of the attitude to affect, or the emotion expressed by the music. …