It is Holy Week in Rome, the heart of christendom. Dusk has fallen and the solemn service of Tenebrae is concluding. One by one the candles are snuffed, leaving the congregation in darkness. For hundreds of years, the papal choir—one of the most conservative musical establishments in the world—observed the entire service in plainchant, from the Lamentations of Jeremiah to the Responsories that narrate Christ's suffering and death. Then, at the very end of the day, the full choir breaks into parts for one piece: Gregorio Allegri's Miserere.

The Medici Pope Leo X first mandated the silent recitation of Psalm 51 at the conclusion of Tenebrae. Each Catholic soul across the world considers, then, David's desperate poetic plea for God's mercy. The Pope's own singers, however, quickly adopted the practice of a fully polyphonic performance of the Psalm (later in the fifteenth century, Palestrina contributed a setting). Allegri joined the papal choir in 1629, serving for the rest of his life. In the 1630s he composed a setting of Miserere mei for Holy Week that eventually became his greatest musical legacy. The papal choir sang it every year from the seventeenth century until the choir collapsed in 1870. Louis Spohr knew the piece, and the young Felix Mendelssohn heard it sung once. The penalty for copying its music, which the papal choir considered its exclusive property, was excommunication.

Allegri's musical structure follows what by then was common practice for the singing of this Psalm: alternation between plainchant verses and different choral elaborations of the chant. His Miserere opens with a five-voiced choir that harmonizes the first Psalm verse, with the chant melody known as the tonus peregrinus. Allegri's music uses the conservative and balanced stile antico, the classic ancient style of Palestrina. Some imitation is present, and Allegri spices the harmonies with rich, dissonant suspensions. A simple chanted verse follows, then a verse sung by a distant choir of four soloists. Each solo verse over the years of its performance became gradually encrusted with a rich oral tradition of abbellimenti, the characteristic traceries of vocal ornamentation by the best singers in the Catholic Church. The great castrati (male sopranos) added an angelic leap to high C at the crux of each solo verse. The very final solo verse leads not into the expected chant, but instead a choral refrain that includes the full nine-voiced texture; gradually, though, the dynamic recedes into the shadows.

© Timothy Dickey, Rovi