Music for Holy Week: Miserere Mei, Deus
Psalm 51 is normally associated with Ash Wednesday. But this setting of the Psalm, written in the 1630's during the time of Pope Urgan VIII by Gregorio Allegri, was composed for use in the Sistine Chapel during the Holy Week (some sources say for Tenebrae on Wednesday; others say Wednesday and Friday; still others Thursday, Friday and Saturday).
The score was kept secret for more than a hundred years until Mozart, aged 14, showed up to hear it. He loved it and went home and wrote it all out from memory. This was apparently forbidden, but hey, he was 14 and you know how 14-year olds are. And after that, the score was out in the world. Thank God.
This from a BBC recording of the choral group The Sixteen, from Manchester, England.