Even though our senses collect a great deal of information about the world, there are many things we cannot sense directly. We cannot see objects that are hidden from view, although we may sometimes see a small part of them. If we observe a twitching tail behind a rock, we may draw the inference that the tail is attached to a hungry tiger. We also cannot directly sense the emotions of others, although we may study their facial expressions and body language for important clues. Since much of what we need to know is hidden from immediate view, we elaborate upon what we can see. Sherlock Holmes was especially clever at elaboration. Consider this passage, narrated by Dr. Watson, from The Red-Headed League:
I took a good look at the man and endeavoured, after the fashion of my companion, to read the indications which might be presented by his dress or appearance.
I did not gain very much, however, by my inspection. Our visitor bore every mark of being an average commonplace British tradesman, obese, pompous, and slow. He wore rather baggy gray shepherd's check trousers, a not over-clean black frock-coat, unbuttoned in the front, and a drab waistcoat with a heavy brassy Albert chain, and a square pierced bit of metal dangling down as an ornament. A frayed top-hat and a faded brown overcoat with a wrinkled velvet collar lay upon a chair beside him. Altogether, look as I would, there was nothing remarkable about the man save his blazing red head, and the expression of extreme chagrin and discontent upon his features.
Sherlock Holmes's quick eye took in my occupation, and he shook his head with a smile as he noticed my questioning glances. "Beyond the obvious facts that he has at some time done manual labour, that he takes snuff, that he is a Freemason, that he has been in China, and that he has done a considerable amount of writing lately, I can deduce nothing else."
Mr. Jabez Wilson started up in his chair, with his forefinger upon the paper, but his eyes upon my companion.
"How in the name of good-fortune, did you know all that, Mr. Holmes?" he asked. "How did you know, for example, that I did manual labour? It's as true as gospel, for I began as a ship's carpenter."
"Your hands, my dear sir. Your right hand is quite a size larger than your left. You have worked with it, and the muscles are more developed."
"Well, the snuff, then, and the Freemasonry?"
"I won't insult your intelligence by telling you how I read that, especially as, rather against the strict rules of your order, you use an arc-and-compass breastpin."
"Ah, of course, I forgot that. But the writing?"
"What else can be indicated by that right cuff so very shiny for five inches, and the left one with the smooth patch near the elbow where you rest it upon the desk?"
"Well, but China?"
"The fish that you have tattooed immediately above your right wrist could only have been done in China. I have made a small study of tattoo marks and have even contributed to the literature on the subject. That trick of staining the fishes' scales of a delicate pink is quite peculiar to China. When, in addition, I see a Chinese coin hanging from your watch-chain, the matter becomes even more simple."Cycle back to the circle!