In honor of Holy Week:

This beautiful piece was composed by Gregorio Allegri (1582-1652), for performance in the Sistine Chapel on Wednesday and Friday of Holy Week.  For a time, according to the oft-told mythical story, the song was the well guarded secret of the Vatican, which forbade its publication, until a 14 year old Wolfgang Amadeus Mozart visited on Good Friday 1770 and later transcribed the entire piece from memory.  This is probably not true, but makes a great story (for a full debunking, read Ben Byram-Wigfield’s 1996 essay, “MISERERE MEI, DEUS, GREGORIO ALLEGRI: A Quest for the Holy Grail?”, pg 16, online here).  There was certainly a mystique about the music that led such as person as Mary Shelley to gush:

But a thousand times over I would go to listen to the Miserere in the Sistine Chapel ; that spot made sacred by the most sublime works of Michael Angelo … The music, not only of the Miserere, but of the Lamentations, is solemn, pathetic, religious – the soul is rapt – carried away into another state of being. Strange that grief, and laments, and the humble petition of repentance, should fill us with delight – a delight that wakens these very emotions in the heart – and calls tears into the eyes, and yet is dearer than any pleasure.
(From Mary Shelley: Rambles in Germany and Italy in 1840, 1842 and 1843. Vol 2. London, Edward Moxon, 1844), Vol 2, 230–31; as cited in Graham Kelly’s essay for the University of York Dept of Music, “A unique singers’ manuscript from the 19th century: Domenico Mustafa’s version of the Miserere of Tommaso Bai and Gregorio Allegri”, which can be found online here.)

The version heard commonly today is not likely what a guest to the vatican would have heard in Mozart’s time.  The “top C” version we all know and love turns out to have been the happy result of an error.  For you musicologists out there, the Wigfield essay mentioned above explains this in detail:   The received version, as it is widely held today, is a mix of Burney’s first choir with a bizarre second choir, congealed into life in the first edition of Grove’s Dictionary of Music & Musicians in 1880. As an illustrated example, W.S. Rockstro showed the first half of the four-part verse as indicated by Alfieri, but then sticks Mendelssohn’s 1831 record of the first half —up a fourth— on the second half of the verse. Ivor Atkins, for his edition of 1951, took Burney’s first choir and final verse, adding this second choir from Grove’s. The problem is that the Mendelssohn abbellimenti is also a record of the first half, apparently sung a fourth higher than written at the time of his visit. It is this that causes musicologists to squirm with the bass jumping from an F# up to a C, followed by the swift gear change into C minor. This error has been repeated in two subsequent editions, produced by respected academics. The result is strangely beautiful, and probably here to stay. It is, after all, one of the most popular pieces of sacred music. However, it is neither a representation of the performance practice of the Sistine Chapel choir, nor a true reflection of how the piece was ever sung there.

A theological point can be made here, and perhaps I’ll embellish it down the road: Sometimes God uses our mistakes to His greater glory.