From the recording Ancient Ayres & Carols for Christmas
from Ancient Ayres & Carols for Christmas CD: The tune was a carol by German composer, Michael Praetorius. The melody migrated to Scandinavia and new words were added that told the legend of Good King Wenzel, King of Bohemia (Czechoslovakia) from A.D. 928 to 935, who was celebrated for his many kind acts for the poor. This remains one of my very favorite carols. I am always surprised that it is not included in church hymnals.