The point of the anecdote is the purpose of this anthology. While the detective story is founded on rules that remain important today, the distinctly American "take" on these rules has vastly enriched the genre. When Rosemary Herbert and I determined to select stories that would trace the evolution of the American detective short story, we discovered that I was far from the first American author to break or bend the rules. My American predecessors had been early pioneers in playing the detective game on their own terms.

But nobody can deny that assumptions, traditions, and rules of the genre remain important. Just what are they?

Early detective fiction was categorised as a tale rather than as serious fiction. As Barzun tells us, Edgar Allan Foe is not only the founding father and "the complete authority" on the form but also the one who "first made the point that the regular novel and the legitimate mystery will not combine."

Why not? Because in the tradition originated by the genius of Poe, the detective story emerged as a competition between writer and reader.

It was a game intended to challenge the intellect. Although Poe himself, in «The Murders in the Rue Morgue,» did arouse awe and horror, the major preoccupation-and innovation-in this story is the introduction of the puzzle. The reader is challenged to attempt to solve it with the clues provided. In the final pages, the reader will learn if his or her solution matches that of the detective.

Given such a purpose, the reader and writer had to be playing by the same rules. Even though the rules are rather self-evident, they were formalised by Monsignor Ronald Knox in his introduction to «The Best Detective Stories of 1928.» His rendition of the rules came to be known as the 'Detective Decalogue.' Perhaps because Father Knox was known as a theologian and translator of the Bible as well as a crime writer, the rules were also referred to as the 'Ten Commandments of Detective Writing.'