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 trumpet is asked to stand away from the group. This is to emulate the call and response between a soloist and congregation at a church service found in many denominations. The other trumpet player should play a flugel horn to create a fourth "mellow" voice.