J. S. BACH Jonathan Berkahn - Victoria University - Victoria ...

After this exposition the cadential phrase returns, ‘accompanied’ by the choir,
and then further development of the fugue subject—with bb.4-5 of the opening theme
unexpectedly present in the orchestra—brings us to the dominant. At this point the
dominant pedal of bb.6-8 appears (in the new key) out of which the soprano soloist’s
line flowers in bb.27-31. A brief double canon at the octave (S-T/B-A) and a repeat of
bb.9-12’s cadential phrase bring the first part of this binary movement to a close.
The opening theme now reappears in the dominant (b.39), this time with the
voices present as well, and is at once subjected to a freely imitative development
which prepares us for a recapitulation (starting at the beginning of the fugal
exposition) at b.46. This recapitulation adheres fairly closely to the first part of the
movement, giving the soprano solo to the alto to allow for transposition; the most
significant difference is that the choir are allowed to finish the movement, singing a
simpler version of the orchestra’s closing material in bb.70-73. This movement is
clearly not a fugue, plain and simple, although the choir does enter with a fugal
exposition. But imitative writing is never absent for long, and (equally to the point)
the subject—in one or other of its forms—is frequently present. Contrapuntal
elements are present in other movements as well. Although the rest of the mass is
even more concise than this movement, Mozart does find room for several brief
fugues: the ‘Crucifixus’ (telescoped) and ‘Osanna’, as well as the more usual ‘cum
sancto Spiritu’ and ‘et vitam venturi’. The last two depart considerably from Mozart’s
usual colla voce orchestration: the orchestra accompanies the ‘cum sancto Spiritu’
fugue with thoroughly Classical broken chords, while that of the ‘et vitam venturi’ has
a more traditional independent counterpoint.
These fugues are not the only signs of Mozart’s contrapuntal learning: the
Gloria is held together by two distinctive thematic elements: a melody in long dotted
minims, suggestive of a Fuxian cantus firmus, and a simple canon at the octave that
288