“You remember,” said he, “that some little time ago when I read you the passage in one of Poe’s sketches in which a close reasoner follows the unspoken thoughts of his companion, you were inclined to treat the matter as a mere tour-de-force of the author. On my remarking that I was constantly in the habit of doing the same thing you expressed incredulity.”

“Oh, no!”

“Perhaps not with your tongue, my dear Watson, but certainly with your eyebrows. So when I saw you throw down your paper and enter upon a train of thought, I was very happy to have the opportunity of reading it off, and eventually of breaking into it, as a proof that I had been in rapport with you.”

But I was still far from satisfied. “In the example which you read to me,” said I, “the reasoner drew his conclusions from the actions of the man whom he observed. If I remember right, he stumbled over a heap of stones, looked up at the stars, and so on. But I have been seated quietly in my chair, and what clues can I have given you?”