“Well, Watson,” said Holmes when our visitor had left us, “what do you make of it all?”

“I make nothing of it,” I answered frankly. “It is a most mysterious business.”

“As a rule,” said Holmes, “the more bizarre a thing is the less mysterious it proves to be. It is your commonplace, featureless crimes which are really puzzling, just as a commonplace face is the most difficult to identify. But I must be prompt over this matter.”

“What are you going to do, then?” I asked.

“To smoke,” he answered. “It is quite a three pipe problem, and I beg that you won’t speak to me for fifty minutes.”

From “The Red Headed League”, The Adventures of Sherlock Holmes
Sir Arthur Conan Doyle, 1891