"It is the only way to protect oneself from being robbed. Keep this axiom before you; it is as good as capital, and will return you good interest. Suspecting you as I have done I laid a trap for you this afternoon--a simple, artless trap. Observe this thin piece of brown paper, observe this little piece of wax which I place upon it. Any person treading on it will carry away with him on the sole of his shoe both the paper and the wax. Do you follow me?"
"Yes, sir," said Abel Death, staring at the paper and moving his tongue over his dry lips.
"Before leaving the house this afternoon," continued Mr. Boyd, "I deposited on the stairs eight very small pieces of this paper, each with a very small piece of wax on the top of it, and placed them on those parts of the stairs which a person coming up or going down would be most likely to tread. Is this quite clear to you?"
"Quite clear, sir."
"It is a singular thing, Abel, that upon the soles of your slippers I do not see one of those pieces of paper or any trace of wax."
"It proves, sir," interposed Abel Death eagerly, "that I spoke the truth when I declared that I had not left the room during your absence, and that I did not go down the stairs."
"But it does not prove, you dog, that no person came up the stairs during my absence!" Abel Death fell back, confounded. "Upon my return a few minutes ago I examined the stairs, and found only two of the eight pieces of paper I deposited there so carefully--so very carefully! Six pieces of the eight I placed there had affixed themselves to the soles of the shoes or boots worn by the person who entered this room while I was away. I asked you if any one had called. You answered no. It was a lie, a deliberate lie, a lie not to be explained away."
"If you will listen to me, sir," said Abel Death, reduced to a state of abject fear, "I think it can be explained away."
"I am listening, Abel Death."
"I made a mistake, sir--I confess it."