The musical arrangement is based loosely on the ancient Christmas carol, "O Come, O Come, Emmanuel" which has previously been covered by a number of artists, including Enya and Belle And Sebastian. Co-producer Daniel Lanois
explained to The National Post
why they borrowed from the hymn: "After my conversation with Bono about future hymns or future spirituals, I did a little studying. In fact, with a friend in Toronto, Lori Anna Reid - she's a great singer from Toronto and she's quite an expert on spirituals. I asked her to fish a few out for me and we had a listening session and that one stood out to me. It's an old church hymn called 'O Come, O Come Emmanuel.' It's not identical, but it's inspired by that, an old public domain melody. I laid down a little piano version of that song, again, chopped it to a tempo. Then I came up with a vocal arrangement. Bono had this 'white as snow; idea. It just slowly came together."