By the time Johann Sebastian Bach was born in 1685, the position of the organ as a focal point of the Lutheran church seemed unassailable, as integral as altar and pulpit. Today, alongside the congregational chorale, the organ is the sound of Lutheranism, a connection exemplified in Bach’s Clavierübung III (1739). This collection of large and small preludes on Martin Luther’s ‘catechism chorales’ cemented the intimate connection of vocal chorale and its elaboration on the organ. But for much of the 200 years between Luther’s Reformation and Bach’s appointment to the Thomaskirche in Leipzig in 1723, the instrument’s spiritual role was far from assured.