The glass delusion is one of the strangest mental illnesses to manifest itself in history. It's stranger still that it was somewhat common, but only among the upper classes of society such as royals and noblemen. This bizarre affliction caused the sufferer to believe that their body, or part of their body, was made of glass. They felt extremely vulnerable and became terrified of smashing into pieces, but often seemed otherwise sane and logical.
Let's take a look at how this strange phenomenon occurred, and some of its most famous victims. Click through the gallery to get started.