Harry Houdini, the famed escape artist from a few years back, issued a challenge wherever he went. He could be locked in any jail cell in the country, he claimed, and set himself free in short order. Always he kept his promise, but one time something went wrong. Houdini entered the jail in his street clothes; the heavy, metal doors clanged shut behind him. He took from his belt a concealed piece of metal, strong and flexible. He set to work immediately, but something seemed to be unusual about this lock. For thirty minutes he worked and got nowhere. An hour passed, and still he had not opened the door. By now he was bathed in sweat and panting in exasperation, but he still could not pick the lock. Finally, after laboring for two hours, Harry Houdini collapsed in frustration and failure against the door he could not unlock. But when he fell against the door, it swung open! It had never been locked at all! But in his mind it was locked, and that was all it took to keep him from opening the door and walking out of the jail cell.