Bach’s “O Lamm Gottes, Unschuldig,” BWV 618: Canon Alla Quinta
Typically, a musical canon involves a melodic line which is imitated by one or more voices after a set duration, resulting in a magical contrapuntal layering. In the chorale prelude for organ, O Lamm Gottes, unschuldig (“O Lamb of God, innocent”), BWV 618, Bach expanded on this idea by creating a canon “alla quinta” (“canon at the fifth”). Unlike a canon in unison, the voices are set a fifth apart. In this …