Miserere mei, Deus
Miserere, (full title: Miserere mei, Deus, Latin for “Have mercy on me, O God”) by Italian composer Gregorio Allegri, is a setting of Psalm 51 (50) composed during the reign of Pope Urban VIII, probably during the 1630s, for use in the Sistine Chapel during matins, as part of the exclusive Tenebrae service on Holy Wednesday and Good Friday of Holy Week.
Miserere was the last of twelve falsobordone Miserere settings composed and chanted at the service since 1514 and is the most popular: at some point, it became forbidden to transcribe the music and it was allowed to be performed only at those particular services, thus adding to the mystery surrounding it. Writing it down or performing it elsewhere was punishable by excommunication.
According to the popular story (backed up by family letters), the fourteen-year-old Mozart was visiting Rome, when he first heard the piece during the Wednesday service. Later that day, he wrote it down entirely from memory, returning to the Chapel that Friday to make minor corrections.
Once the piece was published, the ban was lifted; Mozart was summoned to Rome by the Pope, only instead of excommunicating the boy, the Pope showered praises on him for his feat of musical genius. The work was also transcribed by Felix Mendelssohn in 1831 and Franz Liszt, and various other 18th and 19th century sources survive. Since the lifting of the ban, Allegri’s Miserere has become one of the most popular a cappella choral works now performed.