20th Century. Samuel Barber's Mutations from Bach was first published in 1968 for brass ensemble and timpani. It is based on "Christe, du Lamm Gottes" (Christ, you Lamb of God), a Lutheran hymn often referred to as the "German Agnus Dei." Martin Luther took the Latin words from the Roman mass and the melody from a 1525 Wittenberg publication. The hymn is contained in the Protestant Hymnal known as 190:2. (Wikipedia). Barber states the hymn melody at the outset and then "transforms" or "mutates" it fromits original form into several contrasting episodes, concluding back to the original hymn melody. The idea for this arrangement for 8-part trombone ensemble and optional timpani came from Mr. Sauer's colleague, Per Brevig. This 6-minute composition workswell for advanced performers. -the publisher