as it was, there
were several most instructive points about it."

"Simple!" I ejaculated.

"Well, really, it can hardly be described as otherwise," said Sherlock
Holmes, smiling at my surprise. "The proof of its intrinsic simplicity
is, that without any help save a few very ordinary deductions I was able
to lay my hand upon the criminal within three days."

"That is true," said I.

"I have already explained to you that what is out of the common is
usually a guide rather than a hindrance. In solving a problem of this
sort, the grand thing is to be able to reason backwards. That is a very
useful accomplishment, and a very easy one, but people do not practise
it much. In the every-day affairs of life it is more useful to reason
forwards, and so the other comes to be neglected. There are fifty who
can reason synthetically for one who can reason analytically."

"I confess," said I, "that I do not quite follow you."

"I hardly expected that you would. Let me see if I can make it clearer.
Most people, if you describe a train of events to them, will tell you
what the result would be. They can put those events together in their
minds, and argue from them that something will come to pass. There are
few people, however, who, if you told them a result, would be able to
evolve from their own inner consciousness what the steps were which led
up to that result. This power is what I mean when I talk of reasoning
backwards, or analytically."

"I understand," said I.

"Now this was a case in which you were given the result and had to
find everything else for yourself. Now let me endeavour to show you the
different steps in my reasoning. To begin at the beginning. I approached
the house, as you know, on foot, and with my mind entirely free from all
impressions. I naturally began by examining the roadway, and there, as I
have already explained to you, I saw clearly the marks of a cab, which,
I ascertained by inquiry, must have been there during the night. I
satisfied myself that it was a cab and not a private carriage by the
narrow gauge of the wheels. The ordinary London growler is considerably
less wide than a gentleman's brougham.

"This was the first point gained. I then walked slowly down the garden
path, which happened to be composed of a clay soil, peculiarly suitable
for taking impressions. No doubt it appeared to you to be a mere
trampled line of slush, but to my trained eyes every mark upon its
surface had a meaning. T