Analysis by Key: Another Look at Modulation

ANALYSIS BY KEY
Brahms's A major Sonata for Violin and Piano is a good example. In Chopin's
big dual-key pieces, on the other hand, the f1rst tonic is always supplanted by its
rival - think of the Fantasy, the Second Scherzo, the Second Ballade, etc. I am
not going to address myself here to the question of whether any of these pieces
has only one primary tonic; but I should like to suggest that the problem can't be
explained away by asserting that for Chopin a relative major and minor form a
single extended key. Since when does the notion of'key' involve two tonics of
equal rank?6 (In any case this explanation founders on the F major/A minor
Ballade, whose two keys are not relatives.)
Apparent Centres
In Ex. 2, the beginning of the Chopin F minor Prelude, we saw a passage that
implies F as centre long before there is any tonic harmony. Of course the tonic
appears eventually; the promise of the piece's beginning is kept. But although
music mostly keeps its promises, it need not do so in the obvious way we might
expect; like the Weird Sisters' prophecies in Macbeth, its messages sometirnes
admit of more than one interpretation. Bars 29-36 of the Scherzo movement of
Schubert's Piano Sonata, D.845 (Ex. 6), have a pitch content very similar to that
of Ex. 2. Following a firmly established C major (itself a tonicized III in the
home key of A minor), the passage continues the C harmony, but in a way that
makes it sound like a V in F minor. As the example shows, the expected F minor
never materializes, for the chromatic pitches serve instead to prepare Ab major.
Ex. 6 Schubert: Piano Sonata, D.845, III
MUSIC ANALYSIS 6:3, 1987 295