Although the ornamentation was increasingly delicate and ingenious, 17th-century locks and keys weren’t much more secure than their medieval predecessors. But the 18th and 19thcenturies brought about a new obsession with security. Industrialization made European cities more crowded and helped create a middle class full of people with stuff worth stealing. Theft became more common, and the pressure to thwart it drove locksmiths to new heights. These locks take severe, if somewhat impractical, tacks: Any person using the wrong key in the 1780 lock on the right will find his wrist clamped by the jaws of a fearsome metal lion; anyone jimmying the 1823 lock on the left may get shot by the pistol embedded within it (just barely visible at top right).