Watching Willie’s father leave, the Reverend reenters the white stone home and finds Willie sitting in the corner. “My father,” says the boy. “Yes,” replies the Reverend. “He said he will come again,” Willie says. “He promised.” This moves the Reverend so much that all he can manage to say is, “A miracle.”
The Reverend finds himself profoundly touched by Lincoln’s promise, because no one in the Bardo has ever experienced what Willie has just experienced. Indeed, though the Bardo-dwellers themselves remain tethered to the living world, the people in that world lead lives that have nothing to do with them. As such, Willie’s interaction with his father gives people in the Bardo a sliver of hope that they too will someday be able to reconnect with a world they’ve left behind. Of course, it’s worth noting that Willie and Lincoln haven’t truly interacted—since Willie remains unable to actually communicate with his father—but nonetheless, Lincoln’s promise to return suggests that people in the living world might still care about the Bardo-dwellers.