“How, then, did you deduce the telegram?”
“Why, of course I knew that you had not written a letter, since I sat opposite to you all morning. I see also in your open desk there that you have a sheet of stamps and a thick bundle of postcards. What could you go into the post-office for, then, but to send a wire? Eliminate all other factors, and the one which remains must be the truth.”
“In this case it certainly is so,” I replied after a little thought. “The thing, however, is, as you say, of the simplest. Would you think me impertinent if I were to put your theories to a more severe test?”
“On the contrary,” he answered, “it would prevent me from taking a second dose of cocaine. I should be delighted to look into any problem which you might submit to me.”