Little is known about Johann Sebastian Bach's sonatas for viola da gamba and harpsichord. Are they early works or products of his late period? Do they form a cycle, or are they a collection of independent pieces? Long-time musical partners Atsushi Sakai and Christophe Rousset set out to record these enigmatic works, in which the gamba, as so often in Bach, becomes at once the voice of lamentation and an instrument of dialogue with the divine.