Mark was smoking his cigar outside the door of his house when he saw aman, a stranger, approaching him. Suddenly he ceased to be visible!Mark, who had long desired to see a ghost, rushed into his house torecord the phenomenon. There, seated on a chair in the hall, was thevery man, who had come on some business. As Mark's negro footmanacts, when the bell is rung, on the principle, "Perhaps they won'tpersevere," his master is wholly unable to account for thedisappearance of the visitor, whom he never saw passing him or waitingat his door--except on the theory of an unconscious nap. Now, adisappearance is quite as mystical as an appearance, and much lesscommon.This theory, that apparitions come in an infinitesimal moment ofsleep, while a man is conscious of his surroundings and believeshimself to be awake was the current explanation of ghosts in theeighteenth century. Any educated man who "saw a ghost" or "had ahallucination" called it a "dream," as Lord Brougham and LordLyttelton did. But, if the death of the person seen coincided withhis appearance to them, they illogically argued that, out of theinnumerable multitude of dreams, some _must_ coincide, accidentally,with facts. They strove to forget that though dreams in sleep areuniversal and countless, "dreams" in waking hours are extremely rare--unique, for instance, in Lord Brougham's own experience. Therefore,the odds against chance coincidence are very great.Dreams only form subjects of good dream-stories when the visioncoincides with and adequately represents an _unknown_ event in thepast, the present, or the future. We dream, however vividly, of themurder of Rizzio. Nobody is surprised at that, the incident beingfamiliar to most people, in history and art. But, if we dreamed ofbeing present at an unchronicled scene in Queen Mary's life, and if,_after_ the dream was recorded, a document proving its accuracy shouldbe for the first time recovered, then there is matter for a gooddream-story. {8} Again, we dream of an event not to be naturallyguessed or known by us, and our dream (which should be recorded beforetidings of the fact arrive) tallies with the news of the event when itcomes. Or, finally, we dream of an event (recording the dream), andthat event occurs in the future. In all these cases the actualoccurrence of the unknown event is the only addition to the dream'susual power of crumpling up time and space.As a rule such dreams are only mentioned _after_ the event, and so arenot worth noticing. Very often the dream is forgotten by the dreamertill he hears of or sees the event. He is then either reminded of hisdream by association of ideas or _he has never dreamed at all_, andhis belief that he has dreamed is only a form of false memory, of thecommon sensation of "having been here before," which he attributes toan awakened memory of a real dream. Still more often the dream isunconsciously cooked by the narrator into harmony with facts.As a rule fulfilled dreams deal with the most trivial affairs, andsuch as, being usual, may readily occur by chance coincidence. Indeedit is impossible to set limits to such coincidence, for it wouldindeed be extraordinary if extraordinary coincidences never occurred.To take examples:--
