Andante from Organ Sonata No. 4 in E minor

The organ sonatas, BWV 525 to 530 by Johann Sebastian Bach are a collection of six sonatas in trio sonata form. Each of the sonatas has three movements, with three independent parts in the two manuals and obbligato pedal. The collection was put together in Leipzig in the late 1720s and contained reworkings of prior compositions by Bach from earlier cantatas, organ works and chamber music as well as some newly composed movements. The sixth sonata, BWV 530, is the only one for which all three movements were specially composed for the collection. When played on an organ, the second manual part is often played an octave lower on the keyboard with appropriate registration. Commentators have suggested that the collection might partly have been intended for private study to perfect organ technique, some pointing out that its compass allows it to be played on a pedal clavichord.The collection of sonatas is generally regarded as one of Bach's masterpieces for organ. The sonatas are also considered to be amongst his most difficult compositions for the instrument.