Samuel Barber - Mutations from Bach for brass ensemble and timpani (1967)

This late work is a skilful arrangement of a series of treatments of the chorale melody "O Christ, du Lamm Gottes", a German version of the Agnus Dei. This was music (and a message) that meant a great deal to Barber; Bach's chorale harmonisation and chorale prelude on this theme were among the music he requested for his funeral. The brass ensemble piece was written in the same year as another Barber Agnus Dei, his choral arrangement of the famous Adagio.

Mutations doesn't begin with Bach, but with an earlier setting of the chorale melody by the Hamburg organist Joachim Decker (c.1575-1611). One minute in (timings refer to this performance), at the first entrance of the trumpets, we hear Bach's richer, busier harmonisation, more fully scored than the Decker. From 1'35" onwards, there is a stirring version of the short chorale prelude mentioned above (BWV 619, from the Orgelbüchlein - listen here). This time, the original chorale melody appears in canon, shared between the 1st/2nd trombones and the 1st/2nd trumpets. The rest of the group become bells, weaving ascending and descending scales in and out of the slow-moving chorale. This section folds easily into a brief reprise of the final phrase of Bach's chorale (2'25"), first on horns and tuba, then on trumpets and trombones. 

At this point (2'52"), Barber borrows a particularly beautiful recitative from one of Bach's cantatas, "Du wahrer Gott und Davids Sohn" (BWV 23* - complete performance here). The solo goes to the 1st horn, accompanied by the trombones (original at 7'14" in the video above). Meanwhile, the chorale melody can be found floating high above, in a testing passage for a cup-muted 1st trumpet. Coming full circle, the piece ends with a final, gentle reminder of the Decker chorale, this time on muted horns.

Recently, I've returned to this piece quite frequently, either as a short break from a hectic day, or as a musical palate cleanser - after hearing performers pushed towards their limits, to listen to the simple speech of Barber's beautifully blended brass choir can be a tonic. The recording in the YouTube video is by the 90s edition of the London Symphony Orchestra Brass. It is, of course, very fine, but my favourite remains the performance by the London Gabrieli Brass Ensemble, as part of an excellent programme of US brass music. There's not much in it, but I prefer the slightly more spacious tempo, and the slightly more spacious acoustic (All Hallows, Gospel Oak vs. Barbican). The LGBE record, "From the Steeples and the Mountains" is on the Hyperion label. The third disc in the photo is Volume 6 of the Naxos box of Barber's orchestral music, which I recommend highly to anyone looking for a cheap way to explore beyond the violin concerto and the Adagio. 

* The Bach chorale harmonisation used by Barber can also be found in this cantata, lavishly decorated by the orchestra (13'57").