BWV 675, 66 bars long, is a two-part invention for the upper and lower voices with the cantus firmus in the alto part. The two outer parts are intricate and rhythmically complex with wide leaps, contrasting with the cantus firmus which moves smoothly by steps in minims and crotchets. The time signature has been taken to be one of the references in this movement to the Trinity. Like the two preceding chorale preludes, there is no explicit manualiter marking, only an ambiguous "a 3": performers are left with the choice of playing on a single keyboard or on two keyboards with a 4′ pedal, the only difficulty arising from the triplets in bar 28.See:
