From the introduction: Liminal spaces have captivated us for centuries. These are spaces on the boundary, at the edge between what’s real and what’s unreal. A liminal space can be neither here nor there, and yet be both here and there at the same time. Stories of liminal spaces are common across countries and cultures, though their true nature often isn’t recognized by the uninitiated: the stranger who appears suddenly at a lonely crossroads . . . the troll that snatches at unwary travelers from a hiding spot beneath a bridge where no such hiding spot exists . . . the strangely familiar yet unsettlingly different scene that’s sometimes glimpsed in a looking glass. These are only the most obvious encounters with liminal spaces! Most liminalities are more easily overlooked, being as unconscious as the heartbeat between waking and sleeping, as fleeting as drawing in breath as an apprentice and exhaling it as a master, or as unassumingly familiar—and as fraught with potential—as a threshold that’s crossed a hundred times without incident.