Holy Night” has to be one of the most-sung Christmas songs out there and why not? It’s a pretty song with theologically rich verses and a high note that feels like a tightrope walk for even the most gifted vocalists. But what a lot of people don’t know is that the Christmas Carol has a long legacy of being an anthem of abolitionism.

In 1843, a French poet and wine merchant named Placide Cappeau was commissioned to write a Christmas piece to celebrate the renovation of a church organ in his hometown. Cappeau was keen on the idea, even though he himself was an atheist, and wrote “Minuit, chrétiens,” or “Midnight, Christians.” The music was supplied by a Jewish composer named Adolphe Adams and the song became a holiday hit in France in spite of — or maybe because of — its author’s socialist leanings.