“Oh, you mean the retired sergeant of marines?” Watson is amazed by how Holmes could deduce the man’s history, but Holmes can’t articulate his reasoning and has to think for a while to figure out his chain of deductions. It was based on the man’s hand, his movements, and so on. He tells Watson that there is nothing strange about this: Most people would have difficulty explaining how they know two and two make four. My teacher closed the book and said to me, “You’re just like that. Your derivation is so fast and instinctive that you can’t even tell how you got the answer.”
