An Advent Oldie But A Goody

Do you enjoy listing to Christmas oldies? A number of radio stations have curated lists of their favorites. Of course, when they say oldies, they’re referring to songs that came out primarily in the fifties and sixties. And many of them are actually songs that are based on earlier hits. But there’s also a favorite hymn of this Advent season that’s actually a clever remake of some much, much older music. Can you guess which one it is?