This practice is well exemplified by the Piano Sonata, a work of tragic grandeur, which consolidated Ferguson's reputation at the beginning of the 1940s. Dedicated to the memory of his friend and mentor Harold Samuel, it is arguably his most personal statement. A stark Lento introduction with sombre dotted rhythms sets the mood and originates much of the material. At the core of the Sonata is the tension arising from the semitonal relationship of the opening notes D flat—C natural; from it derives the all-pervading dissonance of a major seventh followed by a minor ninth heard initially in the underlying harmony. So far the tonality is obscure; the introduction closes on C, the dominant of the home key which is firmly established in the first subject of the troubled, chromatic 'Allegro inquieto' which follows.
During the extension of the first subject an anacrusic rhythmic figure of three quavers emerges to become a prominent thematic factor in the movement as a whole; for instance, it is incorporated within the second subject (Poco meno mosso) and appears extensively in the development. The development itself begins mysteriously, as over a rumbling quaver movement in the bass the first theme is heard dolente in augmented rhythm. A truncated recapitulation leads to a long coda where the bass quaver figure of the development returns, but this time in combination with ideas from the introduction. The music dies down to end on a semitone fall from G flat to the tonic F; it is not a resolution, however, but a question mark.
In contrast to the turbulence of the Allegro, the `Poco adagio' is the still centre of the work and is characterised by a serene diatonic theme in D flat major in its outer sections.
In the centre however (Poco più animato) the shadows return with a theme which alludes to ideas from the introduction; yet this same theme is translated to entirely different effect in the coda where it becomes music of benediction and tranquil acceptance. Furthermore this transformation has an emotional significance since it is the only moment in the Sonata where the introductory ideas are not associated with stress.
The harmonic link between the slow movement and finale outlines again the touchstone of the Sonata's dynamism, that semitonal fall from D flat to C which is heard in the bass at the end of the former and the beginning of the latter respectively. As with the first movement, the Finale (Allegro non troppo) follows a traditional sonata format. Despite its minor tonality the principal theme is resolute in mood, and combined with its bounding 6/8 rhythms brings a new sense of purpose to the music.
Soon after, the theme is inverted and remains in this guise for the rest of the work. The second subject (Molto cantabile) again makes much play with an anacrusic rhythm; it leads to the development which is primarily concerned with the inverted first theme and reaches its climax with the rhythm of the theme alone being pounded out in the bass, pesante and fortissimo. From the 'L'istesso tempo' which follows with its overt reference to the central section of the Adagio, and ipso facto the opening Lento, the music gradually reassumes its mantle of grief which the recapitulation is unable to contain.
During the coda (Allegro molto, ma non presto) fragments from the introduction are heard amidst rushing pianissimo quavers; they rise to a climax when, with crushing intensity, the desolate motto theme and the elegiac processional of the dotted rhythms return. The Sonata ends tersely; the searing semitonal clash is juxtaposed, F crashes in the bass.
from notes by Andrew Burn © 1984