the mark of a
dirty hand on the window-frame, and perhaps, in addition to that, you
notice the impress of a hob-nailed shoe on the gravel outside. All these
phenomena have struck your attention instantly, and before two minutes
have passed you say, "Oh, somebody has broken open the window, entered
the room, and run off with the spoons and the tea-pot!" That speech is
out of your mouth in a moment. And you will probably add, "I know there
has; I am quite sure of it!" You mean to say exactly what you know; but
in reality what you have said has been the expression of what is, in all
essential particulars, an Hypothesis. You do not 'know' it at all; it is
nothing but an hypothesis rapidly framed in your own mind! And it is an
hypothesis founded on a long train of inductions and deductions.

What are those inductions and deductions, and how have you got at this
hypothesis? You have observed, in the first place, that the window
is open; but by a train of reasoning involving many Inductions and
Deductions, you have probably arrived long before at the General
Law--and a very good one it is--that windows do not open of themselves;
and you therefore conclude that something has opened the window. A
second general law that you have arrived at in the same way is, that
tea-pots and spoons do not go out of a window spontaneously, and you are
satisfied that, as they are not now where you left them, they have been
removed. In the third place, you look at the marks on the window-sill,
and the shoemarks outside, and you say that in all previous experience
the former kind of mark has never been produced by anything else but
the hand of a human being; and the same experience shows that no other
animal but man at present wears shoes with hob-nails on them such as
would produce the marks in the gravel. I do not know, even if we could
discover any of those "missing links" that are talked about, that they
would help us to any other conclusion! At any rate the law which states
our present experience is strong enough for my present purpose.--You
next reach the conclusion, that as these kinds of marks have not been
left by any other animals than men, or are liable to be formed in any
other way than by a man's hand and shoe, the marks in question have been
formed by a man in that way. You have, further, a general law, founded
on observation and experience, and that, too, is, I am sorry to say, a
very universal and unimpeachable one,--that some men a