This series opens with one sentence spoken to a stranger.
The sentence was correct. What these forty chapters follow is not that he was right, but how he got there.
A Man with Nowhere to Be
John Watson was an army doctor. He was posted to India, moved to the Afghan front, and took a bullet in the shoulder.
Fever came before the wound had healed. After months of it he was judged unfit for further service and sent back to London.
Nothing in England was waiting for him. He had no relations left there, his daily allowance was fixed, and a hotel spends it faster than that.
So he decided to look for someone to share rooms with. The whole of this series begins from that small piece of arithmetic.
In a Hospital Laboratory
Running into his old colleague Stamford, Watson mentioned what he was after. Stamford said he was the second man that day to say so. Someone else had been talking that very morning about wanting to split the rent on a set of rooms.
Then Stamford hesitated. The man was a peculiar sort, he said, and might not be comfortable to live with.
Watson asked what was wrong with him.
The answer was not precise. His mind ran too far toward science, and it made him seem cold. He was not the kind of man who would slip a friend a pinch of poison, Stamford said, but he would certainly swallow it himself if he were curious enough.
When the two of them pushed open the laboratory door, a man at a far bench sprang up with a test tube in his hand.
He had found it, he cried. He had found a way to tell whether a stain is blood.
Six Steps at Once
Stamford made the introduction. Dr. Watson, Mr. Sherlock Holmes.
Holmes shook his hand warmly, with a grip stronger than Watson would have credited him with. And while holding it he added a remark.
“You have been in Afghanistan, I perceive.” (A Study in Scarlet, Chapter 1)
Watson asked how on earth he knew that.
He got no answer. Holmes told him never to mind, chuckled to himself, and announced that the question now was about haemoglobin.
The answer came much later. After the two had taken rooms at 221B Baker Street and settled in, Holmes was explaining his trade when he circled back to that first afternoon.
There Were Steps
He had not been told, he said. He had known. Long habit had run the train of thought through so fast that he arrived without being conscious of the middle, but the middle was there.
Here is the order he retraced.
A gentleman of a medical type, but with the air of a military man. So an army doctor.
His face is dark. His wrists are fair. So the darkness is not his natural colouring, and he has just come from the tropics.
His face is haggard. So he has known hardship and sickness.
He holds his left arm stiffly and unnaturally. So it has been injured.
Only then does the last question arrive. Where could an English army doctor have seen that much hardship and got his arm wounded?
Afghanistan.
Watson smiled and said that it was simple enough, explained that way.
Simple to Follow Is Not Easy to Do
That remark opens the ground this series will work for forty chapters.
Explained, it looks simple. But before it was explained, Stamford was standing in the same room and read nothing at all, and Watson had been looking at his own wrists and his own arm every day without drawing a single conclusion from them.
The same things were in front of everyone and one man saw something else in them. That is what Holmes means, later, when he tells Watson that he sees but does not observe.
Still, this series does not let the rest of it pass.
The first four steps come off Watson’s body. A dark face, fair wrists, a worn look, a stiff arm are all there to be seen by anyone in the room.
The last step is different. It does not come off the body at all. It comes from where the British army happened to be fighting that year, and Holmes could say Afghanistan because he knew that. With a different year, the same five signs would have delivered a different answer.
So the question this chapter leaves is not whether he was right.
It is whether this much observation earns that much conclusion, and where along the way the road is thinnest.
Forty chapters ask those two things, one chapter at a time.
If I reached a conclusion about someone today, how many of the steps between could I actually name?