In terms of psychiatric disorders, some are a little weirder than others. Perhaps weirdest of all is a now-obselete disorder called the glass delusion.
The basic premise of the glass delusion is that people who have it believe that they (or a part of their body) are made of glass or that they have swallowed something made of glass and have it trapped inside them. They believe they are prone to shattering at any moment. This delusion arose in the middle ages; before then (before the invention of glass) people had a tendency to believe they were made of fragile pottery. In the 17th century, one Parisian gentleman was reported by his doctor to believe that his buttocks were made of glass; for his own safety, he wore a cushion strapped to his bottom at all times and refused to sit on any hard surfaces. He was cured when his doctor spanked him firmly, convincing him that his buttocks were not actually breakable. Other oddly successful attempts at cures include that of one doctor convincing an afflicted Spanish prince to lie in a straw bed for his own safety, at which point the doctor lit the straw on fire, forcing the prince to leap up and proving that he was not going to shatter.
Some sufferers of the glass delusion were less anonymous. King Charles VI of France suffered from a variety of psychological symptoms throughout his life, including the glass delusion. He wore specially-made protective clothing reinforced with ribs to hold him together and did not allow anyone to touch him. Princess Alexandra of Bavaria believed that as a child, she had swallowed an entire glass grand piano that was still inside her. She walked sideways through the palace halls to avoid getting stuck in a doorways and even avoided loud noises for fear they would shatter the piano and kill her.
The glass delusion has also been the subject of several works of literature. Miguel de Cervantes wrote The Glass Graduate (1613), the fictional tale of aspiring lawyer Thomas Rodaja who is afflicted as the result of an aphrodisiac gone wrong and is cured by a mystic monk. Constantijn Huygens’ Costly Folly (1622) is about a man who fears that sitting in a chair will shatter his bottom and lying on a pillow will shatter his head. René Descartes’ Meditations on First Philosophy (1641) briefly mentions sufferers of the glass delusion as examples of people whose perceptions differ radically from reality.
Nowadays, the glass delusion has faded into obscurity. Almost no cases have been reported since the mid 19th century. There are only two cases reported in the modern world, both unconfirmed.
The gradual extinction of the glass delusion is probably a good thing. The fewer people there are wandering about (or more likely not wandering about) believing they are made of glass for no apparent reason, the better. Sanity is a lovely thing.