The opening point in the Agnus Dei (Ex. 16-11) recapitulates the beginning of the Kyrie (compare Ex.
16-8), an effect calculated to give this “freely” composed Mass an especially rounded and finished shape.
The technique of composition, not only here but in all the melismatic sections of the Mass, reverts to the
freely imitative style Zarlino called fuga sciolta. Only phrase-beginnings are imitated; continuations are
“freely” adapted to the harmonic design. The concluding Agnus (designated “II” but meant for the third
section, with its separate textual ending “Dona nobis pacem”) expands, following custom, into seven
parts. It is very unlikely that anyone listening to this triumph of art-concealing art (Ex. 16-12a) could tell
without following the score that its luxuriant contrapuntal unfolding was scaffolded around a three-part
canon (bassus I, altus II, cantus II) based, initially, on the Ur-motive. It is a very spaciously laid out canon
in which the parts hardly overlap, again putting a kind of antiphony in place of imitation. The interval of
the canon is a rising fifth that proceeds in two stages, from bassus to altus and from altus to cantus, so that
the first and third voices are in fact a ninth apart. That layout, strange from the purely intervallic point of
view, is harmonically a very strategic move, giving further evidence of Palestrina’s inclination to plan his
works out “tonally,” in terms of fifth-related harmonic regions.
EX. 16-12A Giovanni Pierluigi da Palestrina, Missa Papae Marcelli, Agnus II, mm. 1–10