The humorous ghost is distinctly a modern character. In early literature wraiths took themselves very seriously, and insisted on a proper show of respectful fear on the part of those whom they honored by haunting. A mortal was expected to rise when a ghost entered the room, and in case he was slow about it, his spine gave notice of what etiquette demanded. In the event of outdoor apparition, if a man failed to bare his head in awe, the roots of his...