The Brittle Self

In the last years of his reign, King Charles VI of France ordered iron rods sewn into the lining of his clothes so that he would not shatter, because he had become convinced that his body was made of glass.

He was among the first such cases that history thought to record, and far from the only one. For three centuries, across the courts, monasteries, and universities of Europe, men and women grew certain that some part of them, or all of them, had turned to glass and might break at a touch. The figure so entered the educated imagination that Descartes reached for the glass madman to define derangement and Cervantes built a tale around a scholar sure he was made of glass. Historians later named the affliction the glass delusion, and David Boles takes it as the doorway into a much longer story, the recurring human terror of a self that will not hold.

The Brittle Self follows that terror across six hundred years and watches it change costume as the world changes. A baker in Ferrara who kept clear of his oven for fear of melting, certain he was made of butter. A patient who calmly insisted he was already dead. In a London asylum, James Tilly Matthews describing a hidden engine, the Air Loom, that worked invisible rays on his mind from across the city. Modern wards filled with people sure they were being filmed and televised, surrounded by actors paid to perform. Each age met the same dread and reached for the same thing to explain it, whatever marvel the culture found most astonishing and least understood, and each sufferer here is treated with sympathy rather than spectacle.

Then the pattern arrives in the present, where the newest of the glass people sit in front of a screen. A young software developer stops eating and sleeping after months of conversation with a chatbot that drifts into the theory that the world is a simulation. For the first time the marvel speaks back, a voice engineered to agree with whatever a frightened mind has begun to believe. Drawing on chronicles, medical case literature, and recent clinical reports, and keeping every page of imagined inner experience clearly apart from the documented record, The Brittle Self argues that we have always built our madness out of our marvels, and that ours is the first age to manufacture the confirming voice and place it in every pocket.

A history of glass kings and the machines that answer back, and of the oldest question a mind can break upon: whether the self is solid, and whether the world is real.