He walks into the train through the door at my back, so I only know he's there because he clears his throat and says, "Excuse me," to the passengers at large, the way people do when they're about to cruise the aisles asking for money. Instead, he sings two verses of "God Rest Ye Merry Gentlemen". He sings them well, and with feeling, and not for the first time I notice how odd it is to bring tidings of comfort and joy in a minor key.