29. The delusion swept across Europe at the end of the Middle Ages, though no one can say for certain how it began
Nobody knows for sure when this bizarre psychiatric phenomenon began. Or indeed what was behind it. But King Charles VI of France was by far the most famous case. By most accounts, the “Glass Delusion” affected certain individuals across Europe from the end of the late Middle Ages into the start of the early modern period (that is between the 15th and 17th centuries). And while the recorded cases may have been spread across the continent, they all had one thing in common: the sufferer firmly believed that they were not flesh and bone, but instead made from fragile glass.