As this little book was written some four years ago, I feel able to review it without prejudice. A new book just hot from the brain is naturally apt to appear faulty to its begetter, but an old book has got into the proper perspective and may be praised by him without fear or favor. "The Big Bow Mystery" seems to me an excellent murder story, as murder stories go, for, while as sensational as the most of them, it contains more humor and character creation than the best. Indeed, the humor is too abundant. Mysteries should be sedate and sober. There should be a pervasive atmosphere of horror and awe such as Poe manages to create. Humor is out of tone; it would be more artistic to preserve a somber note throughout. But I was a realist in those days, and in real life mysteries occur to real persons with their individual humors, and mysterious circumstances are apt to be complicated by comic. The indispensable condition of a good mystery is that it should be able and unable to be solved by the reader, and that the writer's solution should satisfy. Many a mystery runs on breathlessly enough till the denouement is reached, only to leave the reader with the sense of having been robbed of his breath under false pretenses. And not only must the solution be adequate, but all its data must be given in the body of the story. The author must not suddenly spring a new person or a new circumstance upon his reader at the end. Thus, if a friend were to ask me to guess who dined with him yesterday, it would be fatuous if he had in mind somebody of whom he knew I had never heard. The only person who has ever solved "The Big Bow Mystery" is myself. This is not paradox but plain fact. For long before the book was written, I said to myself one night that no mystery-monger had ever murdered a man in a room to which there was no possible access.