delicate instrument, and one that is
easily thrown out of gear. Before I proceed, just sum up for yourselves
the facts that I have mentioned: a light seen and presently extinguished
in an apartment supposed to be uninhabited; and a cat of a remarkable
color, which appeared and disappeared in a way that was slightly
mysterious. Now there isn't anything very strange about that, is there?
Very well. Imagine, now, that these unimportant facts are repeated day
after day and under the same conditions throughout a whole week, and then,
believe me, they become of importance enough to impress the mind of a man
who is living all alone, and to produce in him a slight disquietude such
as I spoke of in commencing my story, and such as is always caused when
one approaches the sphere of the unknown. The human mind is so formed that
it always unconsciously applies the principle of the causa sufficiens. For
every series of facts that are identical, it demands a cause, a law; and a
vague dismay seizes upon it when it is unable to guess this cause and to
trace out this law.

"I am no coward, but I have often studied the manifestation of fear in
others, from its most puerile form in children up to its most tragic phase
in madmen. I know that it is fed and nourished by uncertainties, although
when one actually sets himself to investigate the cause, this fear is
often transformed into simple curiosity.

"I made up my mind, therefore, to ferret out the truth. I questioned my
caretaker, and found that he knew nothing about my neighbors. Every
morning an old woman came to look after the neighboring apartment; my
caretaker had tried to question her, but either she was completely deaf or
else she was unwilling to give him any information, for she had refused to
answer a single word. Nevertheless, I was able to explain satisfactorily
the first thing that I had noted--that is to say, the sudden extinction of
the light at the moment when I entered the house. I had observed that the
windows next to mine were covered only by long lace curtains; and as the
two balconies were connected, my neighbor, whether man or woman, had no
doubt a wish to prevent any indiscreet inquisitiveness on my part, and
therefore had always put out the light on hearing me come in. To verify
this supposition, I tried a very simple experiment, which succeeded
perfectly. I had a cold supper brought in one day about noon by my
servant, and that evening I did not go out. When dar