One luckless evening it occurred to me to test my wife's fidelity in a vulgar, commonplace way familiar to everyone who has acquaintance with the literature of fact and fiction. I went to the city, telling my wife that I should be absent until the following afternoon. But I returned before daybreak and went to the rear of the house, purposing to enter by a door with which I had secretly so tampered that it would seem to lock, yet not actually fasten. As I approached it, I heard it gently open and close, and saw a man steal away into the darkness. With murder in my heart, I sprang after him, but he had vanished without even the bad luck of identification. Sometimes now I cannot even persuade myself that it was a human being.