Book excerpt: These paperback editions makes Peter Williams's influential scholarship available to a wider field of readers, including those with an interest in the ever-expanding discussions of original instrumentation and its implications for modern performance. Professor Williams examines Bach's organ works piece-by-piece, reconstructing for the present-day performer and listener the original context of the work. Form and style are analysed, with abundant musical examples and frequent allusions to the views of other commentators. Each volume contains a preface, calendar, lists of musical sources and references, and an index.