The temptation to form premature theories upon insufficient data is the bane of our profession. - Valley of Death

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. - A Scandal in Bohemia

It is a capital mistake to theorise before one has data. It biases the judgement. - A Study in Scarlet

My name is Sherlock Holmes. It is my business to know what other people don't know. - The Adventure of the Blue Carbuncle

On the contrary, Watson, you can see everything. You fail, however, to reason from what you see. You are too timid in drawing your inferences. - The Adventure of the Blue Carbuncle

No, no: I never guess. It is a shocking habit destructive to the logical faculty. What seems strange to you is only so because you do not follow my train of thought or observe the small facts upon which large inferences may depend. - The Sign of Four

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. - A Study in Scarlet

Holmes the Investor

  Sherlock Holmes was best known for his sleuthing skills, but we speculate that he was also an astute investor. He appears to have had the benefit of a significant endowment, and although it is unclear if he brought the same level of analysis to his investment portfolio as he brought to his murder cases, we speculate that quants would approve of his methods.

  Although little is known of Holmes's investments, it appears that his creator, Sir Arthur Conan Doyle, was a conservative investor who did not chose to "chase returns." The final directive in his will states:
"I direct very considerably that all investments of my monies be kept, so far as possible, in government stocks or in first mortgages or such other investments as promise security rather than a high rate of interest."