Yet we must not be too liberal; and a ghost story can be brought
into our charmed and charming circle only if we have made up our
minds to believe in the ghosts; otherwise their introduction would
not be a square deal. It would not be fair, in other words, to
propose a conundrum on a basis of ostensible materialism, and then,
when no other key would fit, to palm off a disembodied spirit on
us. Tell me beforehand that your scenario is to include both
worlds, and I have no objection to make; I simply attune my mind to
the more extensive scope. But I rebel at an unheralded ghostland,
and declare frankly that your tale is incredible. And I must
confess that I would as lief have ghosts kept out altogether; their
stories make a very good library in themselves, and have no need to
tag themselves on to what is really another department of fiction.
Nevertheless, when a ghost story is told with the consummate art of
a Miss Wilkins, and of one or two others on our list, consistency
in this regard ceases to be a jewel; art proves irresistible. As
for adventure stories, there is a fringe of them that comes under
the riddle-story head; but for the most part the riddle story
begins after the adventures have finished. We are to contemplate a
condition, not to watch the events that ultimate in it. Our
detective, or anyone else, may of course meet with haps and mishaps
on his way to the solution of his puzzle; but an astute writer will
not color such incidents too vividly, lest he risk forfeiting our
preoccupation with the problem that we came forth for to study. In
a word, One thing at a time!

The foregoing disquisition may seem uncalled for by such rigid
moralists as have made up their minds not to regard detective, or
riddle stories, as any part of respectable literature at all. With
that sect, I announce at the outset that I am entirely out of