A la Chapelle Sixtine is a very unusual work, inspired by Liszt’s hearing two very different motets in the Sistine Chapel: the famous Miserere mei Deus
by Gregorio Allegri (1582–1652), and Mozart’s last work of this kind—the Ave verum corpus
, K618, of 1791. The story of Allegri’s work is well-known: composed for the papal choir at the time of Urban VIII, the work was not permitted to be published, and it circulated for centuries in a handful of written copies. The fourteen-year-old Mozart copied the piece from memory. Although the original piece is famous for its antiphonal chorus with high Cs, Liszt concentrates on the marvellous harmonies of its beginning, and uses them to generate a passacaglia in G minor whose variations come to a stormy climax before the Mozart piece is revealed in the simplest transcription in B major. By way of one of Liszt’s finest modulatory passages, the variations return, much shortened, before the Mozart reappears, this time in F sharp—incidentally, it is this passage which Tchaikovsky used as the basis for the slow movement of his fourth orchestral Suite, opus 61, ‘Mozartiana’. Liszt extends Mozart’s music to allow a gentle modulation to G major, and the piece finishes with distant hints of the Allegri in the bass. Liszt made an orchestral version of the piece which has, at the time of writing, never been published or performed, a version for piano duet, and a rather more frequently performed version for organ—with the title improved by the adding of the initial word ‘Évocation’.
from notes by Leslie Howard © 1991