Double assassinat dans la rue Morgue

Some people have a special kind of mind. They love puzzles, secret codes and difficult questions, and they enjoy solving them the way a strong man enjoys using his muscles. To other people, their answers seem almost like magic. But there is no magic in it. It is simply careful thinking.

A good chess player, for example, must pay close attention to every move. But a truly clever card player does much more than that. He watches the faces of the other players. He notices how each person holds his cards, and how he puts them down on the table. A quick look, a careless word or a nervous hand tells him something. After two or three rounds, he knows what cards everyone is holding, as if they had turned them face up. The important thing is not simply to look, but to know what to look for.

The story I am going to tell is an example of this kind of thinking.