Abstract: A locking device including a labyrinthic passageway through which a ball may be moved until arriving at a position adjacent an associated locking mechanism that is operable solely in response to the presence of the ball. In an exemplary embodiment, the labyrinthic passageway is concealed in the bottom of an open-topped walled container and the locking mechanism is in communication with a sliding plate member employed to close the container. With the plate member in its closed position and the ball placed at a starting location within the passageway, yet away from the locking mechanism, the container cannot be opened until the ball has been encouraged, by spatial manipulation of the container, to negotiate the labyrinth, arrive at a position adjacent the locking mechanism, and operate same solely by the impression of its weight thereupon.