ill very likely be to go off for the police, and set
them on the track of the burglar, with the view to the recovery of your
property. But just as you are starting with this object, some person
comes in, and on learning what you are about, says, "My good friend,
you are going on a great deal too fast. How do you know that the man who
really made the marks took the spoons? It might have been a monkey that
took them, and the man may have merely looked in afterwards." You would
probably reply, "Well, that is all very well, but you see it is contrary
to all experience of the way tea-pots and spoons are abstracted; so
that, at any rate, your hypothesis is less probable than mine." While
you are talking the thing over in this way, another friend arrives, one
of that good kind of people that I was talking of a little while ago.
And he might say, "Oh, my dear sir, you are certainly going on a great
deal too fast. You are most presumptuous. You admit that all these
occurrences took place when you were fast asleep, at a time when you
could not possibly have known anything about what was taking place. How
do you know that the laws of Nature are not suspended during the night?
It may be that there has been some kind of supernatural interference in
this case." In point of fact, he declares that your hypothesis is one
of which you cannot at all demonstrate the truth, and that you are by no
means sure that the laws of Nature are the same when you are asleep as
when you are awake.

Well, now, you cannot at the moment answer that kind of reasoning. You
feel that your worthy friend has you somewhat at a disadvantage. You
will feel perfectly convinced in your own mind, however, that you are
quite right, and you say to him, "My good friend, I can only be guided
by the natural probabilities of the case, and if you will be kind enough
to stand aside and permit me to pass, I will go and fetch the police."
Well, we will suppose that your journey is successful, and that by good
luck you meet with a policeman; that eventually the burglar is found
with your property on his person, and the marks correspond to his hand
and to his boots. Probably any jury would consider those facts a very
good experimental verification of your hypothesis, touching the cause
of the abnormal phenomena observed in your parlour, and would act
accordingly.

Now, in this suppositious case, I have taken phenomena of a very common
kind, in order that you might see what are