Wir glauben all' an einen Gott, Schöpfer (Giant Fugue), BWV 680

Contained in the Clavier-Übung III,"Wir glauben all' an einen Gott, Schöpfer" is a four-part fugue in the Dorian mode of D based on the first line of the Luther's hymn. It is written in the Italian style, apparent both in the instrumental trio-sonata style and in the ingenious use of the full range of Italianate semiquaver motifs. The five notes in the original hymn for the opening melisma on Wir are expanded in the first two bars and the remaining notes are used for the countersubject. There is exceptionally no cantus firmus, probably because of the exceptional length of the hymn. Features of the remainder of the hymn, however, suffuse the writing, in particular the scale-like passages and the melodic leaps. The fugue subject is adapted to the pedal as a vigorous striding bass with alternate footwork; its quasi-ostinato character has been consistently interpreted as representing a "firm faith in God": a striding bass line was often used by Bach for Credo movements. During each occurrence of the semiquaver part of the subject in the pedal, the music modulates into a different key while the three upper parts play in invertible counterpoint, so that the three different melodic lines can be freely interchanged between the three voices. These highly original transitional passages punctuate the work and give a coherence to the whole movement. Although the added G sharp makes it difficult to recognize the chorale melody, it can be heard more clearly later on, singing out in the tenor part. In the final manualiter episode the ostinato pedal figures are taken up briefly by the tenor part before the movement draws to a close over a final extended restatement of the fugue subject in the pedal.