On one of his European tours, the master magician and locksmith Harry Houdini found himself locked in by his own thinking. After he had been searched and manacled in a Scottish town jail, the old turnkey shut him in a cell and walked away. Houdini quickly freed himself from his shackles and then tackled the cell lock. But despite all his efforts, the lock wouldnt open.
Finally, ever more desperate but completely exhausted, he leaned against the door--and it swung open so unexpectedly that he nearly fell headlong into the corridor. The turnkey had not locked it.