Trio Sonata for Organ No. 2 in C minor

The Trio Sonata in C minor, BWV 526 (also known as Sonata No. 2 for organ or Trio Sonata No. 2) is part of a collection of six trio sonatas for organ, BWV 525-530. These works represent one of Bach's most outstanding contributions to the organ repertoire, adapting the Italian trio sonata genre (typically for two upper melodic instruments and basso continuo) to a single instrument: the organ, with two manuals and obbligato pedal. The collection BWV 525-530 was compiled in Leipzig between approximately 1727 and 1730 (some sources indicate as late as 1732). Bach's autograph manuscript dates from this period. Some individual movements may have come from earlier compositions (transcriptions or reworkings of cantatas or chamber works), but the sonata BWV 526 as such is considered part of this late compilation in Leipzig.

Bach compiled the sonatas primarily for his eldest son, Wilhelm Friedemann Bach, who was around 20 years old at the time, so that he could practice and perfect his organ technique. They are considered among Bach's most difficult and mature works for organ, focusing on technical and polyphonic mastery of the instrument rather than everyday liturgical use. The first movement (Vivace) is a transcription or reworking of the symphony from the second part of the cantata Die Himmel erzählen die Ehre Gottes, BWV 76.

Sonata BWV 526 consists of three movements, following the classical Italian model of sonata da chiesa (without dance):

1. Vivace – Energetic and concertante opening movement, with alternating tutti and solo passages, in ritornello form.
2. Largo (in E-flat major) – Slow, expressive, and lyrical central movement, developed from a triad motif followed by descending sighs.
3. Allegro – Fast and virtuosic finale, with a simple initial theme (two whole notes) and a contrasting section that exploits descending chords; the pedal is heavily involved in fugal processes.

Each movement maintains a strict texture of three independent voices, with an elaborate contrapuntal character and concertante elements. It is composed for organ with two manuals (right and left for the two upper melodic voices) and obbligato pedal (for the bass voice), simulating the ensemble of a chamber trio sonata (two violins or flutes + basso continuo) through the independence of the parts.