The second section is a four part double fugue on a single manual.
The third section is a five part double fugue for full organ.
The fugue is a double fugue in four voices with two distinct subjects developed in separate expositions.
Bach reflected the duality of the words of the psalm in the opening chorus by creating a double fugue.
At the end of the piece, the last movement's main theme is combined with the first movement's main theme in a double fugue.
There are three sections played without pause: a skittish fast section, a ruminative slow one and a driving double fugue.
The second movement is a double fugue in C minor, and uses as text Psalm 40, verses 2, 3, and 4.
The passacaglia is followed, without break, by a double fugue.
Many of the pieces feature multiple sections, with a few double fugues and some variation fugues present.
Musical analysts, accustomed to anchoring their thoughts in the firm ground of double fugues or 12-tone method, have been equally confounded.