A Study in Scarlet

by Arthur Conan Doyle

within eccentric limits his knowledge was so extraordinarily ample and minute that his observations have fairly astounded me. Surely no man would work so hard or attain such precise information unless he had some definite end in view. Desultory readers are seldom remarkable for the exactness of their learning. No man burdens his mind with small matters unless he has some very good reason for doing so.

"I consider that a man's brain originally is like a little empty attic, and you have to stock it with such furniture as you choose. A fool takes in all the lumber of every sort that he comes across, so that the knowledge which might be useful to him gets crowded out, or at best is jumbled up with a lot of other things so that he has a difficulty in laying his hands upon it.

"One's ideas must be as broad as Nature if they are to interpret Nature," he answered.

It was not the father, however, who first discovered that the child had developed into the woman. It seldom is in such cases. That mysterious change is too subtle and too gradual to be measured by dates. Least of all does the maiden herself know it until the tone of a voice or the touch of a hand sets her heart thrilling within her, and she learns, with a mixture of pride and of fear, that a new and a larger nature has awoken within her. There are few who cannot recall that day and remember the one little incident which heralded the dawn of a new life.

So thrilling had the man's narrative been, and his manner was so impressive that we had sat silent and absorbed. Even the professional detectives, blasé as they were in every detail of crime, appeared to be keenly interested in the man's story.

"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."

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. There is no branch of detective science which is so important and so much neglected as the art of tracing footsteps.