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Unlock Your Inner Sherlock: Case One "A Study In Scarlet"

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This is a rough draft of a novel idea I have for exploring how Sherlock Holmes thinks. Each chapter will be a "case study" of Sherlock Holmes and his methods. Feel free to offer suggestions and comments by leaving me a line at


The phrase, “It’s elementary my dear Watson”, appears nowhere in the original stories of Sherlock Holmes penned by Sir Arthur Conan Doyle. Holmes’ process is anything but elementary. Maybe that’s why Conan Doyle didn’t have him say that, even though I can totally imagine Holmes saying something like that. In the stories, Sherlock displays powerful lines of logic and reasoning capabilities.

For example, in our first meeting of Sherlock Holmes we are introduced to Sherlock Holmes. “You have been in Afghanistan, I perceive.”

“How on earth did you know that?” I asked in astonishment. Watson’s surprise is genuine and I don’t blame him. Holmes had never met Watson before this moment and Watson’s friend, the one that introduced the two, had not informed Holmes of Watson’s existence. Yet Holmes asks a very particular question about Watson’s recent past with clarity and precision. “You have been in Afghanistan.” That’s such a cool statement to make.

How do you observe someone for the first time and recognize where they have been? How do you draw big conclusions from small details? How do you begin to think like Sherlock Holmes? The answer is elementary, but it will take a while to explain some of the details. Let’s get started with the basics and work our way up to the basics. You read correctly. Thinking like Sherlock Holmes is in itself basic, but there are many layers to the steps. Additionally, there will be plenty of effort required to enact the changes that are necessary to start the journey. But don’t worry. This book will help you navigate those waters.

In the book a number of the ideas presented will be re-emphasizing of ideas that are core to deductive and inductive reasoning. Also a constant exploration of lateral thinking and analysis of situations will be written about extensively. I want to stress that a lot of the thought processes Sherlock performs are repetitive and he has some common principles that govern his thoughts.

Let’s start with the first example of Holmes and Watson’s first meeting to demonstrate how we can replicate the great detectives process.

“You Have Been In Afghanistan”

To begin this study, I would like to discuss how we see the world around us. Your eyes are a powerful tool for taking in information. One of the most powerful skills of Sherlock Holmes involves his ability to see the world differently than the rest of us. Though we see, hear, smell, touch, and taste a seemingly endless array of things, our brain does not force us to register everything. This is to our benefit.

Imagine for a moment if your Prefrontal Cortex (PFC), the CEO of the brain, were to figuratively say, “I know you are driving down the highway at 60 miles per hour, but I noticed there was a banana peel on the highway. Turn your head please and look at it.” That probably wouldn’t be the best idea. In the grand scheme of things, that banana peel probably wasn’t worth your time. Your PFC does a great job at prioritising what is relevant and what isn’t, what is useful for the task at hand and what is a waste of your brains resources. Just as a literal CEO has to manage the resources of a company to execute a plan, your PFC has to manage the brains resources to help you navigate life.

When driving a car, the best use of your mental resources is to focus on the world around you and how you manage your steering wheel, gas pedal, brakes, and instrument panels. When playing a game of tennis, your best use of mental resources are to focus on the ball, your position, and the position of your opponent. But how do we get good at any of these tasks? We train our brains to perform these complex tasks by repetition/practice, analysis, and performance. In time, a task like playing a musical instrument can become second nature. Let’s explore the meeting of Sherlock Holmes and Watson in The Study In Scarlet.

When Sherlock sees Watson for the first time, I speculate that he didn’t spend more than a glance looking at Watson. Let’s read that passage.

At the sound of our steps, he glanced round and sprang to his feet with a cry of pleasure. “I’ve found it! I’ve found it,” he shouted to my companion, running towards us with a test-tube in his hand. “I have found a re-agent which is precipitated by hemoglobin, and by nothing else.” Had he discovered a gold mine, gred not have shone upon his features.

“Dr. Watson, Mr. Sherlock Holmes,” said Stamford, introducing us.

“How are you?” he said cordially, gripping my hand with a strength for which I should hardly have given him credit. “You have been in Afghanistan, I perceive.”

What did the text say? “He glanced round”. He then came towards Watson and his companion. Afterwards, he shook hands with Watson and made his claim about Watson recently being in Afghanistan. So the time that Holmes had spent actively observing Watson was likely no more than a couple of seconds, if that.

In fact, later in the story Holmes says, “Nothing of the sort. I knew you came from Afghanistan. From long habit the train of thoughts ran so swiftly through my mind, that I arrived at the conclusion without being conscious of intermediate steps. There were such steps, however. The train of reasoning ran, ‘Here is a gentleman of a medical type, but with the air of a military man. Clearly an army doctor, then. He has just come from the tropics, for his face is dark, and that is not the natural tint of his skin, for his wrists are fair. He has undergone hardship and sickness, as his haggard face says clearly. His left arm has been injured. He holds it in a stiff and unnatural manner. Where in the tropics could an English army doctor have seen much hardship and got his arm wounded? Clearly in Afghanistan.’ The whole train of thought did not occupy a second. I then remarked that you came from Afghanistan, and you were astonished.”

Why does it matter that Holmes was able to glean that much information so quickly from a glance?

It matters because one of the first effects it has on us and Watson is the feeling of suspicion as well as disbelief. How did he come to that conclusion without ever having met Watson? It’s like an unsolvable puzzle has just been solved right in front of our eyes. But that’s the thing I want to highlight. The speed at which he reaches a conclusion is what makes his process amazing, not the actual process itself.