As we passed through the Diogenes Club, I was struck by my friend's actions. He paused by a chessboard which was set up in an unoccupied alcove, and hesitated before moving a knight.
Later, outside the Club, he explained the matter. "A somewhat reclusive opponent, Watson. Formidable, but extremely private; this game is my only contact with him. I have reason to believe he may be the mental equal of the late Professor Moriarty of unfortunate memory; certainly I fancy that I detect some resemblance in his patterns of thought."
"His name, Holmes?"
"I have only the initial, Watson. A."
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