If the Baroque had an equivalent of TV’s Who do you think you are? there would be no better musical candidate than Johann Sebastian Bach. The 18th-century backroom researchers would have a relatively easy ride, mind you, because Papa Bach, meticulous in all things, wrote out his own genealogy in 1735 at the same time as he preserved some of his ancestors’ music in the 200 or so brittle, yellowed pages that make up his Alt-Bachisches Archiv (Archive of the Elder Bachs).

Thus it is that we come to know about the predecessors of a musical dynasty that lasted over 200 years and spanned six generations producing more than 50 known musicians, many of them composers of merit. Even more remarkable is that so many of them excelled despite a generally insular, non-cosmopolitan outlook. It wouldn’t be until Johann Sebastian’s sons set forth on their various travels that the Bach diaspora would spread across Europe.

In these days where the record companies encourage musical omnivores to indulge in an increasingly varied diet, there can be few more satisfying sections of the catalogues to graze...