Of all the great composers, Johann Sebastian Bach is perhaps the least fathomable. A musical perfectionist, his compositions perhaps speak for themselves, but the man himself remains frustratingly elusive.

Johann Sebastian BachJohann Sebastian Bach ( 1685 – 1750)

A well-known organist and a respected if not especially famous composer in his day, Bach was born in Eisenach on March 21 (Old Style) or March 31 (New Style). Early posts in Arnstadt, Mühlhause, Weimar and Cöthen preceded his move to Leipzig in 1723, where he was to remain as cantor of the famous Thomaskirche until his death in 1750.

From the relatively few documents associated with his career, and the fewer that reference his music, he emerges as a shadowy personality: an esteemed colleague to be sure, but a stubborn and often belligerent employee, quick to take offence when confronted with perceived attempts to encroach on his professional rights and responsibilities.

The music is another matter. Revered by fellow composers and music-lovers from Mozart to Beethoven, and from Mendelssohn (who “rediscovered” the St Matthew Passion in 1829) to contemporary composers like Penderecki and MacMillan, Bach regularly tops the poll of “Greatest Composers of All Time”.

It...