The second rule is that you may go only where you do not exist.” She pointed at the locket. “There’s only one of you, June, just like there’s only one of those lockets. That will never change. The locket around your neck disappeared when you crossed because it already lives here. It ceased to exist. Your mind can exist in two places at once, but your body cannot. So, if you walked through the door right now and went back to a time in which you already exist in the future—say, 2022—you, also…disappear.”
