Oh, Day Full of Grace

This has always been one of my favorite hymns and, now, I know a bit more about it.  From the Christian Classics Ethereal Library website, I learned that the song was probably written in Sweden or Denmark and that three manuscript copies of the hymn exist, not one of which was dated later than 1450 AD.  Considered one of the "best known of all Pre-Reformation songs," the singing of it was likely prohibited by the church, as the aforementioned article relates:

The ordinances of the church, furthermore, expressly forbade congregational singing at the church services, holding that, since it was unlawful for the laity to preach, it was also impermissible for them to sing in the sanctuary.  It is thus likely that a Danish hymn had never been sung, except on a few special occasions, in a Danish church before the triumph of the Reformation.

Being Lutheran, I cannot imagine the elimination of hymn singing.  The article continues to explain how, even though such songs were prohibited in church, hymns were still sung at home, thereby preserving them for Christians today.