Johann Sebastian Bach is one of the most unfathomable composers in the history of music. How can such sublime work have been produced by a man who seems so ordinary, so opaque—and occasionally so intemperate?

John Eliot Gardiner grew up passing one of the only two authentic portraits of Bach every day on the stairs of his parents’ house, where it hung for safety during World War II. He has been studying and performing Bach ever since, and is now regarded as one of the composer’s greatest living interpreters. The fruits of this lifetime’s immersion are distilled in this remarkable book, grounded in the most recent Bach scholarship but moving far beyond it, and explaining in wonderful detail the ideas on which Bach drew, how he worked, how his music is constructed, how it achieves its effects—and what it can tell us about Bach the man.