The remaining ejaculations on “Alleluia,” for each of which Byrd invented a new motive and wove a
new point, are liturgical. In his setting they punctuate a texture that has become so interpenetrated with
imitative cells and little homorhythmic blasts as to make the task of unraveling them a wholly pointless
and thankless exercise. This is the ultimate—the farthest point the ars perfecta reached before it gave
way to new stili moderni or froze into the mummified state known as the stile antico. Byrd, who lived
until 1623, was the very last composer for whom the ars perfecta was not a stile antico but a living style
to sustain the best imaginings of the greatest musical minds.
Our comparative survey of Palestrina and Byrd at the latest extremity of the ars perfecta has shown
nothing if not the extraordinary versatility that pliant medium had achieved over the century of its growth
since the humanist embrace of Josquin. Why was it abandoned? It is not enough simply to invoke progress
(at best) or change (at least) as the general, inevitable condition of human history. One must try to account
for changes, especially changes as fundamental as this one, in specific terms, as responses to specific
pressures.
EX. 16-21 William Byrd, Non vos relinquam (Gradualia, Book II)