The Glass Delusion: An Affliction Suffered by Mostly Nobility?

Mental illness has plagued humanity for as long as it has existed. One of the most puzzling manifestations of this was the glass delusion.

Mar 12, 2023By Molly Dowdeswell, MA Early Modern History, BA History
glass delusion mental illness explained


Thought to have origins in the medieval period, the glass delusion is a unique and puzzling mental condition that seems to have plagued the upper classes of medieval and early modern society. The illness was characterized by the belief that one was made entirely or in part of glass and, therefore, likely to smash or shatter.


André Du Laurens, the Glass Delusion, & Early Modern Medical Theory

glass delusion andre du laurens
André Du Laurens line engraving, unknown date (possibly 17th century) via The Wellcome Collection


André du Laurens (1558-1609) was the royal physician of the French King Henry IV (1589-1610). Within his casebooks can be found a record of the glass delusion. Here, he tells of a lord who seemed to be suffering from this mental health condition. Laurens specifies, however, that in every other sense, the man was rational and could go about his daily life. He was able to keep relationships with his friends, but he urged them not to come anywhere near him.


Laurens, alongside other early modern medical theorists, believed that the cause of the illness lay within the cause of all other illnesses in this period: the four humors. This theory, the dominant medical theory since the Ancient Greek period, stated that the body contained four humors or liquids. These humors were blood, phlegm, yellow bile, and black bile. If any of these liquids were off balance, then the individual would become ill, and in order to cure the patient, their humors would have to be re-balanced.


If it was deemed the illness was caused by an excess of blood, for example, the patient would have their blood let; one method of doing so is with leeches. Or, if the illness was caused by an excess of bile, the patient may be given a laxative.


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The humors were not only about physical health; they were linked to mental health as well. Each liquid was related to a mental state. An excess of black bile was tied to melancholy, a mental state which can loosely be tied to what, in the modern period, is depression or extreme sadness.


glass delusion four humors
The four qualities, elements, humors, and temperaments, unknown artist, c. 19th century, via The Wellcome Collection


The glass delusion was linked, by Laurens and others, to this humor. The delusion was seen as a symptom of melancholy, which in turn was a symptom of an excess of black bile. Because black bile was cold and dry, medical professionals thought it could easily imprint itself onto the sufferer’s imagination.


This would leave them susceptible to a manifestation of melancholy; for some, this manifestation took the form of the glass delusion. Laurens argued that people who suffered from melancholy could look at glass and be at risk of not just identifying with the object but believing they were made of it.


The delusion was also mentioned in the work of the English scholar Robert Burton. In his The Anatomy of Melancholy (1621) which was about low moods and how they contributed to illness, he agreed that the glass delusion was a manifestation of melancholy, but he stated it was fear-induced. Burton suggested that people who suffered from melancholy often experienced symptoms such as paranoia, which only exacerbated the glass delusion.


As well as references in learned writings, there were also mentions of the delusion in works of fiction. One of the most famous of these is in Miguel de Cervantes’ (1547-1616) short story entitled The Glass Graduate (1613). In this tale, the hero is poisoned when eating a quince, which was meant to have been an aphrodisiac. The trauma from the event manifested into a glass delusion.


Famous Victims

alexandra amalie von bayern
Portrait of Alexandra Amalie von Bayern by Karl Joseph Stieler, 1838 via Schönheitengalerie, Schloss Nymphenburg


The delusion certainly claimed a few famous victims, not least because it was most common among the upper classes in medieval and early modern society. It was thought to affect wealthy, educated men the most because of some of the connotations of black bile. It was believed and generally accepted that black bile was thick and sludgy, which meant that when the body produced it in excess, the body would feel heavy, sluggish, and perhaps sad.


Furthermore, it was the humor that was often associated with intellect. It was thought that people who were poets, philosophers, or scholars were more prone to a melancholic disposition. Therefore, because the glass delusion was thought to be so closely linked to melancholy and black bile, it was, in consequence, also linked to intellectuals.


However, it is also important to note that the sources may also be skewed in presenting this story. Intellectuals were by nature the most likely to leave a written record of their mental illness, whereas people of the lower classes who were illiterate or women who did not have the power to do so are lost from the historical narrative.


It is, therefore, important to acknowledge that it may only appear this way. People from the lower classes and women may have suffered from the disease as well; we just do not know.


glass delusion charles vi bedridden
Charles VI bedridden and his physician, in Froissart’s Chronicles, c. 1300s, via Gallerix


Perhaps the most famous sufferer was the French King, Charles VI (1368-1422), who was reported to have wrapped himself in blankets and worn reinforced clothing in order to prevent his entire body from smashing. Charles also prohibited courtiers from coming near him in case they shattered him.


Another public figure who suffered from the delusion was Caspar Barlaeus (1584-1648). Barlaeus was a Dutch polymath who, it seems, had a series of mental breakdowns related to the glass delusion.


There was also the Princess Alexandra of Bavaria (1826-75), who suffered from the glass delusion. She believed that as a child, she had swallowed a glass piano and was at risk of it shattering inside her. She, like Charles, attempted to prevent herself from being knocked or pushed for fear of this happening.


Why Did People Suffer From the Glass Delusion?

glass delusion melancholy temperament
A depressed scholar surrounded by mythological figures, representing the melancholy temperament by J.D. Nessenthaler, 1750 via The Wellcome Collection


We have seen above how people in the medieval and early modern periods theorized about the causes of the delusion, but how was it actually caused and why?


Many believe that it may have had something to do with the fact that during the 17th century, clear glass was a relatively new material, or at least to some people. It was often seen to be magical as many people struggled to understand how something like sand, for example, could be manipulated into glass.


Professor Edward Shorter, a historian of psychiatry at the University of Toronto, has argued that this sense of awe and wonder may have been linked to the glass delusion. He states that the newness and magical elements of clear glass could lead to its manifestation.


Shorter argues that the mind had a tendency to attach similar delusions to new materials as well as technological advantages. For example, he points to cement delusions of the 19th century, or the belief in the modern era that the CIA is downloading people’s thoughts and reading people’s minds.


glass delusion johann becher
Johann Joachim Becher. Line engraving by W. P. Kilian, 1675, via The Wellcome Collection


This fascination with glass prompted the German alchemist Johann Becher to write in Physica Subterranea (1669) that “Man, like all animals, is glass and can return to glass.” He claimed that he was able to transform dead bodies into glass so that people could surround themselves with dead relatives in the form of fancy vases!


Becher theorized that every plant and animal, in its glass form, had its own color. For example, and as expected, plants in their glass form were green, whereas humans were made from milky white glass.


Furthermore, before the delusion centered on glass, it was centered around a belief that one was entirely or partly made of pottery or even butter in some cases!


Some, like the psychoanalyst Adam Phillips, have argued that the delusion manifested because, in the periods when the disease was most common, society was concerned with anxieties about fragility, transparency, and personal space or privacy. The belief that one was made of such a fragile material so easily broken is often believed to have been a mental manifestation of these often overwhelming pressures.


The Death of the Delusion?

glass delusion bethlem london
The [Mental] Hospital of Bethlem [Bedlam] at Moorfields, London; seen from the south, with three people in the foreground by J.T. Smith, 1814, via The Wellcome Collection

It seems that in the 1830s, all cases of the glass delusion vanish from records. Many have assumed that this was because of modern advancements in the understanding of mental illness. However, contemporary scholars have found this may not be the case.


Dutch psychiatrist Andy Lameijin has been researching contemporary cases of the illness. He even found a case at his own hospital, stating, “It was an authentic case – it was unmistakable that it was a glass delusion.” The man was brought into the University Clinic in Leiden in 1964 and claimed he was made of glass. Lameijin jumped at the chance to talk to someone who had a real-life experience with this interesting illness. He talked to the patient for several hours, hoping to uncover how the illness manifested in order to shed some light on the historical cases. He discussed with the patient how he felt and how he believed himself to be made of glass despite being able to see his own limbs.


Lameijin conducted further research on the illness in the past and discovered that it had not, in fact, died out in the 1830s. He found a lecture from 1883, which was recorded in the archives of an Edinburgh mental hospital and contains references to the glass delusion.


glass delusion bethlem
Bethlem Hospital, London. Oil painting by an unknown artist, c. 1600, via The Wellcome Collection


The records showed that of 300 female patients who were suffering from some kind of mental illness, there was one who was convinced her legs were made out of glass. Another psychiatrist then approached Lameijin with a case he had located in the archives of a Dutch hospital dated from the 1930s. Again, a woman was admitted to the psychiatric hospital because she also believed her legs to be made of glass. The records state that she was terrified of human contact, so much so that nurses could not get her to change her clothes. Fortunately, the record also states that she recovered but only after treatment.


In conclusion, the glass delusion provides an interesting insight not only into the care and understanding of medieval and early modern mental illness but also into the societal pressures of the day. Understood now to be the possible manifestation of intense and overwhelming pressure and/or anxiety, the illness tells us a lot, not just about early medical care but also how people responded to the societies within which they lived.

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By Molly DowdeswellMA Early Modern History, BA HistoryMolly graduated from the University of Birmingham with a master's degree in early modern history and from Swansea University with a bachelor’s degree in history. She has a long-standing interest in the subject and enjoys researching and writing on a broad range of historical topics and is most interested in the history of medicine and disease. Molly is currently working as a writer based in Birmingham, England and is planning on returning to university to complete a PhD in history.