This arrangement of the traditional Christmas carol takes the form of a five-part (ABACA) rondo. Each variation repeats the melody (essentially) directly, with the accompaniment providing drastically different textures.
The “A” section features a flowingly-syncopated two-part interpretation of the theme, incorporating the third cello for the “Gloria…” chorus for additional contrapuntal texture. The “B” section incorporates a triplet-based accompaniment, continuing the sense of flow before a return to the “A” section. In the “C” section, a somewhat-frantic sixteenth note harmonization draws on the syncopation of the primary countermelody. Finally, the first section is restated.
It is critical to be comfortable with the notes of the individual parts, particularly in the faster accompaniment parts, so that the trio can appropriately balance each part through every section.