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

unorthodox means, though very effective, of approaching the subdominant entry in
b.38. This is the only point at which the fugue steps outside the usual range of keys
(there are no actual entries outside this range); but Mozart was to use this technique to
achieve much more curious tonal results.
His fugue begins in a straightforward enough manner, oscillating between tonic
and dominant. The end of the exposition is followed by a cadence in F (VII), then a
group of entries on B flat (III), E flat (VI), and C minor (iv)—nothing out of the
ordinary. An unexpected G sharp in the bass at b.19 then raises the key a whole tone
to D minor (where there is another entry) before sinking back immediately to C minor,
after which the next entry is in F minor (b.24). From this very distant key Mozart has
to hoist the music back up bodily by a rosalia which lands first on G minor, then on A
(major: dominant of D minor), at which point tonal equilibrium returns for the
moment. There is more ‘bootstrapping’ in store, however, as an entry in C minor
(b.32) is pushed up to D minor (b.36), and then yet further to E minor (b.40)! Only the
most precipitate descent (E minor, D minor, C minor; bb.42-44) can restore some
semblance of tonal coherence, and this concludes the first part of the fugue. The
second part begins with a new exposition of an inverted form of the subject, so the
exigencies of subject/answer relationships keep matters on an even keel for a while. A
B flat major entry in b.61, however, is soon followed by one in A flat, and another
hasty sequential ascent is required (A flat, b.66; B flat minor, b.67; C minor, b.68).
Still more rosalias occur in bb.75-77 (A minor to G minor), and bb.87-88 (D minor to
C minor). This propensity for tonal movement by step, rather than fifths or thirds, is
unique within Mozart’s output, and can probably be attributed to the influence of J. E.
Eberlin.
A related issue concerns the phrase-structure of the fugue. The subject is two
bars long, and entries continue at this distance throughout the exposition. This in itself
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