My very first idea was to use the BACH initials as a basis for the work - not as the melodic
motif often used by composers, but rather as a harmonic structure. This is possible because in the German musical tradition, B stands for B flat and H for B natural. This led to the thought that there would be four short sections, each led by a different soloist, forming an emotional journey: Lamentoso (mournful), Ardente (fervent), Inquieto (restless) and Sereno (peaceful).
The double bass leads the first section, B. Lamentoso (B flat major). The cello leads the next, A. Ardente (A major), faster and higher in pitch to reflect the change of mood, and when the viola soloist urgently interrupts in C. Inquieto (C major), the scene is set for a big climax. In the final section, H. Sereno (B minor), the mood, persuaded by the violin soloist, quietens and eventually leads to a brief quote from the famous chorale from the St. Matthew Passion, O Haupt voll Blut und Wunden which ends the work, in calm and peace, with a 'tierce de Picardie'.
In turn, each soloist carries the linear activity as protagonist on this emotional journey, and
the accompaniment to each section is dominated by the “tonality” indicated. But there is also a mysterious “misty” overlay, only dissipating after the viola’s tempestuous climax.
The cluster of notes that makes up this “mist” is formed from the octatonic scale, in each case incorporating notes of the triad of the relative section to determine its tonality (B flat major, C major etc).
Each section therefore uses only the notes of the octatonic scale1 associated with it - until the viola begins to incorporate a chromatic scale2 - and it is only in the final section that the
familiar diatonic scale3 appears and the mist is dissipated. Therefore, although the overall feeling of the four sections alters to travel spontaneously and 'organically' through the arc of the piece, each section (B.A.C.H.) is rigorously organized and controlled with similar internal ingredients as well as within a "master plan." This, for me, is the essence of Bach.