Built upon Christian numerology, the third book of Johann Sebastian Bach’s Clavier-Übung (Keyboard Practice) may have aspired to be more a Mass for organ than a collection of related smaller pieces. It opens and closes with what has since been commonly catalogued as the Prelude and Fugue in E-flat major, BWV 552.  

The three-part Prelude follows the triple symbolism of the Holy Trinity, with the Father as a dotted rhythm; Son as a lighter, simpler idea; and Holy Ghost as the all-encompassing 16th-note melody. The five-voice triple Fugue is popularly referred to as “St. Anne,” because its subject sounds similar to an English hymn tune with that name. —Gregg Wager