“‘O Christmas Tree’ means Christmas for me. When I was young, I was in a children’s choir, and we would sing all the Christmas songs, including this one, which we’d sing in French. I think there’s a version of it in any language and in any country, so I’ve always felt this carol to be very universal. And as a cellist and an artist, I feel like a citizen of the world, so with this song it feels as if I’m speaking to many of you deeply.”