A masterclass in modulation achieved by studying one of Bach's Chorales. We examine the choice of harmony and modulation, the part writing, the use of accented and unaccented passing notes, plus other features of the Bach Chorale style. Useful for anyone wanting to improve their ability to write harmony, to analyse harmony, or to understand the detail of Bach's style. Join us on this exciting journey to delve inside the mind of the great J. S. Bach.