Bach compiled six “sonatas” for organ, reworking and expanding upon various earlier pieces. The fourth of these is designated as a “Trio sonata” in E minor, BWV 528, which simply describes three-part music written for two manuals and pedal.

The opening and imitative Adagio-Vivace is a transcription of the sinfonia from the second part of the cantata Die Himmel erzählen die Ehre Gottes, BWV 76. The middle Andante movement in B minor similarly continues imitative interplay between the two voices in the manuals, while the triple-metered final movement, Un poco allegro, which has also been paired with the Prelude and Fugue in G major,  BWV 541, carries the imitative process into all three voices, properly forming a fugue.