The Marquise of Brezé, sister of Cardinal Richelieu only sat surrounded by cushions, because she was convinced that she had a backside of glass. This noble family provided very illustrious characters as well as outrageous ones. The Cardinal Richelieu ended his life believing that he was a horse, and whinnied as he circled the billiard table. His brother fell into the delusion of believing himself to be God the Father.
The number of madmen who believed to be of glass – like Tomas Rodaja, the degreed follower of Cervantes – today is not as abundant as in old times. It is interesting that this craze decreased since the invention of unbreakable glass.