This piece was written in the thirteenth Century by an unknown composer. It was set as a single melodic line as many Gregorian chants were constructed. Lush, modern harmonies have been added to make it the popular Christmas piece it is today. The first clarinet is the featured player in this arrangement and first states the melody alone. This is to emulate the call and response between a soloist and congregation at a church service found in many denominations. It has been adapted here for 2 flutes and 2 clarinets.