" Father Wanderly, have you seen a demon or evil spirit actually leave the body? What did it look like? Could you see anything? Did you see a wisp, like smoke over a campfire? Does the demon get sucked into a void, clutching on to the old, possessed body like a life raft? Or does it go quietly, like a child leaving her parents' home for the final time? If you couldn't see anything, if the spirit was invisible, then how could you know if the exorcism really, truly worked? "

― Paul Tremblay , A Head Full of Ghosts