The Fantasy for Organ is based on a programme – the transition of autumn into winter. This composition centers around the key of C-sharp minor. The work begins with a 21-note theme played softly in the pedal, a theme which forms the basis for the entire piece. There follows a development in continuous quintuplet-note figures. The quintuplets are meant to suggest images of falling leaves swirling in the wind. The music unfolds with a sequential selection of the notes of the 21-note theme, shifting frames forward until all of the notes have been utilized. The first part ends with a pronounced restatement of the 21-note theme in the pedal, fading down to a short caesura before the second theme enters. The second theme, in contrast, is quiet, in stream-harmonies of triads. It is meant to evoke images of blue sky, still air, and sunlight streaming through colored leaves. The work next leads to a beating pedal base, then a re-entrance of the quintuplets in the minor mode, suggesting the development of a chill in the air. The latter passage leads to thin, major-mode quintuplets in the treble only, suggesting falling of the first snowflakes. There follows an increasing intensity of the snowflake figures, leading to a treble trill in the manual and the entrance of the 21-note theme in the pedal, developing into a fugal progression. The fugue proceeds with increasingly dissonant focus, suggesting a developing storm of snow, giving way to the main development section. The main section consists of quintuplets, presented in louder notes from the organ and a pronounced, double-pedal counterpoint. This section suggests a snowstorm. Then, quintuplet passages open into the original 21-note theme in the treble, in triadic streams, followed by a fugal progression of the theme leading to a caesura. The second theme quietly enters again, but increases in intensity, giving way to a re-entrance of the quintuplet figures in full-organ register with an extended scale figure in the bass. The figure is repeated in mirror counterpoint with double-pedal notes. The composition ends in the minor mode, with three punctuated chords, implying a final end to autumn.