Unless Teller sees the symptoms of astonishment—mouth agape, eyes widened, pupils dilated—he doesn't consider the trick a success. "The magic show is a competition," he says. "The audience is trying to figure you out. They aren't suspending their disbelief—they're trying to expose you as a scam artist." This is what makes magic so difficult: The magician must sell people a lie even as they know they're being lied to. Unless the illusion feels more real than the truth, there is no magic.