Mutations from Bach

Although Barber’s one work for brass ensemble has achieved nothing like the popularity of his Adagio for strings, and probably never will, it is fairly clearly by the same composer. Written in 1967, more than thirty years after the Adagio, it is inspired by the same love of polyphony, the same interest in church modes, and the same contemplative attitude. Basically, the Mutations are not so much about Bach as about a plainsong melody “Christe, du Lamm Gottes” (Christ, Lamb of God), which runs through the piece in one form or another from beginning to end. It is heard first in an early 17th-century version, harmonised for congregational performance, by Joachim Decker. Bach makes his first entry at the same time as the trumpets with the same tune, as he presents it in his Cantata No.23, “Du wahrer Gott und Davids Sohn.” There is also a chorale-prelude treatment of the tune in Bach’s Orgelbüchlein, which duly appears here with its carillon of descending scale figures introduced by trumpet and taken up by the others. A melodious horn solo, based on an episode in the Cantata, is a timely change of textural and thematic interest before the “Christe, du Lamm Gottes” is finally recalled in Decker’s harmonisation.