PREFACE
The peculiar construction of the first four stories in the present collection will probably strike both reader and critic and seem to call for some explanation, which I accordingly proceed to supply.
In the conventional "detective story" the interest is made to focus on the question, "Who did it?" The identity of the criminal is a secret that is jealously guarded up to the very end of the book, and its disclosure forms the final climax.
This I have always regarded as somewhat of a mistake. In real life, the identity of the criminal is a question of supreme importance for practical reasons; but in fiction, where no such reasons exist, I conceive the interest of the reader to be engaged chiefly by the demonstration of unexpected consequences of simple actions, of unsuspected causal connections, and by the evolution of an ordered train of evidence from a mass of facts apparently incoherent and unrelated. The reader's curiosity is concerned not so much with the question "Who did it?" as with the question "How was the discovery achieved?" That is to say, the ingenious reader is interested more in the intermediate action than in the ultimate result.
The offer by a popular author of a prize to the reader who should identify the criminal in a certain
