in the alto and tenor voices; and finally, in the last section, high in the treble and, as the climactic close approaches, quasi-ostinato in the pedal, thundering out beneath the two sets of upper voices. In the second section it is played against quavers; and in parts of the last, against running semiquaver passagework. As the fugue progresses, this creates what Williams has called the cumulative effect of a "mass choir". In later sections, to adapt to triple time, the first subject becomes rhythmically syncopated, resulting in what the music scholar Roger Bullivant has called "a degree of rhythmic complexity probably unparalleled in fugue of any period."First sectionThe first section is a quiet five-part fugue in the stile antico. The countersubject is in crotchets. There are two stretto passages, the first in thirds (below) and the second in sixths.Second sectionThe second section is a four-part double fugue on a single manual. The second subject is in running quavers and starts on the second beat of bar 37. The first subject reappears gradually, first hinted at in the inner parts (bars 44-46) then in the treble of bar 54 before rising up from the lower register as a fully fledged countersubject (bars 59-61).Third sectionThe third section is a five-part double fugue for full organ. The preceding bar in the second section is played as three beats of one minim (a hemiola) and thus provides the new pulse. The third subject is lively and dancelike, resembling a gigue, again starting on the second beat of the bar. The characteristic motif of 4 semiquavers in the third beat has already been heard in the countersubject of the first section and in the second subject. The running semiquaver passagework is an accelerated continuation of the quaver passagework of the second section; occasionally it incorporates motifs from the second section. At bar 88, the third subject merges into the first subject in the soprano line, although not fully apparent to the ear. Bach with great originality does not change the rhythm of the first subject, so that it becomes syncopated across bars. The subject is then passed to an inner part where it at last establishes its natural pairing with the third subject: two entries of the third exactly match a single entry of the first. Apart from a final statement of the third subject in the pedal and lower manual register in thirds, there