Johann Sebastian Bach

Johan Sebastian Bach's appointment as Kapellmeister at the city of Cöthen was basically a happy one, not because of any great esteem inherent in the title but because the Prince of Cöthen was a true music lover with a voracious appetite for the kind of pure instrumental music that the composer had had little time for in his previous position. This work is in fact an arrangement of the Trio Sonata for two flutes and basso continuo in G major, BWV 1039, composed around the same time, a process of musical re-evaluation that bears witness to what is arguably Bach's most important contribution to the development of eighteenth century chamber music: the elevation of the harpsichord from subordinate, partly improvised basso continuo to equal (sometimes superior), fully written-out musical partner in the duo sonata style.

The process in reality was simple, requiring only that the right hand of the harpsichord assume the role of the missing third instrument; in the case of this sonata, the flute part not taken over by the keyboardist is moved down to a register more congenial to the viola da gamba. The normal four-movement mold of the Baroque sonata da chiesa is at work in this piece: Adagio, Allegro ma non tanto, Andante, Allegro moderato. The strong movement-to-movement connection is most easily seen and heard in the way that the opening Adagio, in luxuriantly flowing 12/8 time, has no final cadence of its own but rather connects directly to the following Allegro via a half cadence (cunningly, the opening movement winds down to G minor, the major mode appearing only as the next movement begins). Both these first two movements open in the traditional imitative style of the Baroque trio sonata. A third of the way into the Allegro ma non tanto movement, Bach turns the melody upside down and proceeds to give it a new contrapuntal treatment; two-thirds of the way in, the original form of the subject returns over a dramatic dominant pedal. Far less energetic and outgoing is the languid Andante, whose ever-repeating sixteenth note mini-arpeggios and broken bass octaves cover a wide and colorfully chromatic harmonic distance in just 18 bars of music. A wonderful moment, radiant within the movement's languid E minor tonality, is achieved when Bach arrives at D major at the exact midpoint. Once the eighth notes of the final Allegro moderato begin, they hardly ever rest. Bach seems to be thoroughly enjoying his contrapuntal prowess here, even in the very first measure, when the opening gesture of the harpsichord right hand is used, in inverted fashion, to initiate the bass line.

-- AllMusic.com