Glass Delusion: Why Some People Think They are Made of Glass...

What if you once had a love, and it was a gas, but it soon turned out they had a bum of glass? Wouldn’t the fact that they couldn’t sit down for fear of breaking their buttocks complicate matters slightly? Yes, it would definitely complicate matters for all concerned and it might sound strange, but believing that parts or even the whole of your body was made of glass and therefore liable to shatter at any time was a real concern amongst many people, especially during the mediaeval period. Known as “glass delusion”, this is one of those niche psychological oddities that has fascinated people, including me, as soon as they hear about it, so I’m pretty psyched to get to write about it for you.

A Glass Case of Emotion — What It Is

OK, let’s get this sorted out at the start. It’s obvious that this was a mental illness of some kind. Are we here to make fun of mental illness? No. Are we here to learn about an interesting thing from the past and maybe crack a few jokes along the way? Yes. I’m not a psychologist and I sure as heck know Simon isn’t, so we’ll have to rely on bigger brains than ours for some explanations here. Luckily, there’s a bit of information to be found about this strange malady so let’s get into what it actually was.

Cases of people suffering from glass delusion appear mainly in Europe between the 14th and even through to the 19th century although it peaked in the 15th and 17th centuries. There were a few ways in which this delusion could present, and we’ll get into specific examples in a minute, but the main symptoms were either:

• thinking that parts of your body, usually extremities, although sometimes your organs, had temporarily turned to glass
• thinking your entire body had turned to glass
• thinking you had been turned into a vessel made of glass
• thinking you had ingested a glass object or
• feeling that you had become invisible or unseen by others, as though you were a pane of glass

Obviously, mental health services were not really the best in the past, nor was knowledge of psychology or even medicine in general, so if you came down with anything other than the common, non-plague, cold you were basically screwed. This case is slightly different, though, as it was clear to everyone apart from the one suffering from it, that their body was not, in fact, turning into glass. Treatment therefore ranged from indulging the sufferer until the delusion passed by keeping a safe distance away or wrapping soft things around them to protect them, to a kind of reverse psychology approach to try and shake them out of the idea that a piece of them was made of glass by providing proof that it wasn’t.

Here’s an example of this from a piece on History.com by Hadley Meares: “Another man believing he possessed a glass rear end was beaten by his doctor, in the hopes he would realize it was his flesh that was sore from the thrashing.” There is no further information on whether this worked or not and, to be honest, it just sounds like glass bum man was a bit of a masochist.

The Ruling Glass — Famous Examples

While this phenomenon was a comparatively rare thing to suffer from, we know about it today as some big names from the past came down with it. There are two historical figures who are the poster children for glass delusion so let’s find out more about how this disorder manifested in their lives.

The first and maybe best known sufferer is Charles the Sixth, the King of France from 1380 until his death in 1422. Poor Charles had a very difficult life, psychologically speaking, and went from being known as Charles the Beloved at the start of his reign to Charles the Mad by the end of it. I suppose it’s salient to point that out, as glass delusion was one of many things he suffered from over the course of his life rather than it just being an isolated incident.

Things started unravelling in 1392 when, in an apparent fit of confusion, paranoia and rage while on a military campaign, Charles attacked and killed four of his own knights before falling into a coma. Early the next year, another incident occurred which is unlikely to have soothed any mental anguish he might have been carrying from the attack. At a masked ball in January 1393, Charles and several of his noblemen friends dressed as so-called “wild men”.

They wore linen costumes which had been soaked in pitch or resin and had plant material and rags stuck all over them so they looked all shaggy, savage and wild. They also apparently had masks made of the same stuff on so nobody realised who they were. Some accounts say they were sewn into the costumes and others also say all the dancers were chained together.

Because of the highly flammable nature of the outfits, people had actually been sensible and moved all the open flames and torches to the sides of the room when the wild men entered.

At first everyone was having a great time as these apparently fabled spirits of the wood cavorted around, behaving quite outlandishly and rudely under the protection of anonymity and being really rich. Unfortunately though, the king’s brother Louis and his friend had rocked up late and came into the hall, flaming torches in hand to see what all the commotion was about. As Louis tried to get a better look at the dancers, a spark from his torch landed on one of them and the whole gang of wild men went up in flames.

Luckily for the King, he happened to be talking to the Duchess of Berry who was wearing a massive dress and threw it over him to put him out and protect him from the other dancers. Another man saved himself by either jumping into a tub of water or a barrel of wine — accounts vary — but the four other men died that night or shortly after of their wounds. According to Michel Pintoin, the Monk of St Denis: “four men were burned alive, their flaming genitals dropping to the floor … releasing a stream of blood”.

This event became known as the “Bal des Ardents” or the “Ball of the Burning Men”.

After this traumatic event, King Charles the 6th’s mental state deteriorated rapidly and his outbursts and unpredictable episodes increased. One of the delusions that came and went over the remaining years of his life, is that his whole body was made of glass. This meant he took to wearing special clothing reinforced with metal rods that would protect his upper half from shattering.

His tailors didn’t seem to be up to the task of making reinforced trousers though, as he spent a lot of his time lying still while wrapped in soft blankets and cushions. He also didn’t want to touch or get too close to anyone so as to reduce the chances that he would break. This is kind of inconvenient if you’re a king, however, Charles was not much more than a figurehead by the end of 1393 anyway, with his reign overseen by a procession of regents.

He was so convinced that his body had turned to glass that at one point he went through a period of about 5 months without washing or changing his clothes. He died at the age of 53 but thanks to his publicly recorded behaviour, he is the most well-known victim of glass delusion.

Princess Alexandra of Bavaria was also known to suffer from glass delusion, although in a different form to King Charles. This also happened a lot later, as Alexandra was born in 1826, several hundred years after the king. As with Charles the 6th, however, she also had other psychological issues that had been noted at the time and was known to be in “delicate health”.

She probably suffered from some form of obsessive-compulsive disorder and was known to have her bedroom thoroughly cleaned every day as she was afraid of germs which is kind of the opposite of what was going on with Charles. She also mainly wore white and never married, despite having interested suitors, with her family citing her fragile health as a reason to keep her single. This likely ended up ultimately working in her favour as in her early twenties, Alexandra became convinced that she remembered swallowing a small glass piano as a child.

As she had grown, so had the piano inside her, meaning that she had to take care moving and walking around in case it damaged her internal organs.

Alexandra died in 1875 at the age of 49 but seemed to work out a good way to deal with her psychological issues as she became a prolific writer, publishing poetry, essays and plays and donating the proceeds to charity. These two royals seem to bookend the most popular time period for glass delusion but there were many more sufferers in between, as well as references to it in works of literature. The most notable was “El Licenciado Vidriera”, a short story by Miguel de Cervantes which was published in 1613, between the two parts of his most famous work, Don Quixote.

It’s variously translated as “The Glass Graduate” or “The Glass Lawyer” and in it the protagonist, a quick-witted young lawyer named Tomás, is given a fruit laced with a love potion. He eats the fruit, the love potion doesn’t work and he becomes very ill. When he wakes up, he believes his entire body is made of glass.

The combination of his strange condition and his way with words makes Tomás something of a celebrity. He does come out of his glass delusion, however, and to escape from all the attention he’s getting, he joins the army and eventually dies in battle, the end.

This story came out right in the midpoint of our two royal glass bookends and it seems that glass delusion was definitely a thing that people were aware of, rather than Cervantes making up something bizarre out of thin air.

The Shattering Truth — Why Was This Happening?

Maybe because King Charles the 6th was so well-known, glass delusion was quite the fad, especially among the aristocracy and upper-classes across Europe between the 15th and 17th centuries. Sufferers were known as “glass men” and, according to an article on JSTOR by Amelia Soth: “a debate swelled over whether its study belonged in the realm of medicine or faith, whether it was a disease of the body or the soul.”

The fact is, though, that while it seems to have been a delusion only affecting the higher echelons of European society, it could easily have affected anyone and been even more widespread than we know. If old Bob in the third shack on the left suddenly announces that he can’t hobble to the market because his leg’s turned into glass, that will not be noted for posterity, one) because he’s not important and two) there probably wouldn’t have been anyone literate around to record his strange ailment. This kind of delusion almost seems like a luxury when you think about it, as Bob might not have had any nice soft things to wrap around his glass leg.

He might not have had other people to do things for him, either, so if Bob couldn’t get out and about, Bob wouldn’t be able to survive. It also seems likely that most sufferers from glass delusion didn’t get it out of the blue. They may have been aware of the issue first, meaning that the majority of sufferers were therefore from the higher rungs of society, being familiar with the luxury glass items being created in Venice at the time and also rubbing shoulders with other people who had come down with the delusion.

Bob probably didn’t have any Venetian glass doo-dads in his shack so the thought of his leg turning into a fragile, transparent object wasn’t something that was likely to pop into his head.

As Molly Dowdeswell writes on thecollector.com: ”(…)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.”

This is why glass delusion has become seen as something of an upper class ailment. It was apparently very distressing for some, but there’s still the sheen of luxury, nobility and beauty that the glass represents.

This also hints that maybe people said they were turning into glass as some sort of social one-upmanship. Could it have been some kind of mediaeval meme, with people potentially pretending to suffer from glass delusion because they believed it also inferred some sort of upper class status on them and people would think of them as more important or something? Assuming that their family or servants or whoever actually cared about them, these people, usually men as we’ve mentioned, would have been treated gently, wrapped up protectively and generally babied until they got better and who doesn’t want to be looked after every once in a while?

You may also be asking at this point — why glass? Glass was not a new substance at this time in history. Glass beads dating back thousands of years BC have been found and it was being put to decorative use in Pharaohs’ tombs centuries before King Charles thought he was turning into it. There was actually a shift in glass making at this time, however.

Glassmaking on the island of Murano in Venice was coming on leaps and bounds starting around the 13th century and accelerating into the 15th, with major innovations and expert skill levels making it the most sought after glass in Europe. If you were a person of means, you had to get you some Murano glass.

For the slightly less initiated of the Middle Ages, glass also held a magical power as a transformative substance capable of changing state and colour. I think we’ve had the argument about whether glass is technically a solid or a liquid before and the conclusion I came to was that there are people willing to die on both hills. According to the first google result that popped up, “In terms of molecular dynamics and thermodynamics, it is possible to justify various different views that it is a highly viscous liquid, an amorphous solid, or simply that glass is another state of matter that is neither liquid nor solid.”

I one hundred percent feel like an amorphous solid from time to time so maybe this is more relatable than I originally thought. The article by Philip Gibbs does then go on to say that for all practical everyday uses, glass is a solid. But anyway, back in the day, people weren’t talking about thermodynamics, they were talking about alchemy.

Transmutation was a big part of the alchemical tradition, which was basically trying to get any old boring metal to turn into gold. The other main goals of alchemy were to create perfect health and long or immortal life but as we can all see, that hasn’t gone very well. The transforming of base metals into gold or a humdrum substance into a precious one is the idea we’re interested in here, though. Metaphorically, we can see how glass delusion ties in with alchemical thinking, maybe with people linking it to metamorphosis and the transformation into something more precious.

As Victoria Shepherd wrote in her 2022 book “A History of Delusions”: “the appeal of glass, a wondrous new material, as a metaphor for a person’s sense of themselves, is not difficult to understand in this context. To be made of glass is to be precious – rare, but fragile; it is an instruction to others to admire you, but not to get too close. There is something essentially magical, spectral about glass… . Glass perfectly symbolizes a sense of both supreme refinement and a nail-biting sense of vulnerability and contingency”

There was also a literal interpretation of the transmutation idea, though. In 1669, German alchemist Johann Becher published “Physica Subterranea”. His idea was that human bodies could be synonymous with glass vessels — not just metaphorically, he actually wanted to turn corpses into other things.

Living things were made up of the same substance found in glass, so that after they died, Becher reckoned, their bodies could be reformed as decorative glassware. Plants could be made into green vases while human bodies could be transformed into lovely milky yellow pieces. While this could solve the issue of what to do with corpses, it’s not actually possible.

Humans and glass do share the component of silica but it’s not present in large enough amounts in the human body to be able to make glass out of it. This does draw something of a parallel to poor old King Charles the 6th, though. Remember his Burning Man ball which was one of the seminal moments in the story of his mental health struggles?

Glass is forged in a fire and turns from sand into a fragile, transparent substance. The King was part of a fiery death scene so maybe his subsequent glass delusion was a direct result of that accident: the fire turned him into glass.

As we mentioned earlier, even though he was the king, it was clear that Charles wasn’t in his right mind for most of his adult life. Glass delusion seems to have appeared more frequently in people who already had other mental illnesses but mediaeval doctors did have ways of diagnosing and treating these issues. Well, at the time they thought they did, anyway. This leads us on to one of my favourite areas of medical knowledge in the past, the four humours.

Laughing Your Glass Off — The Humours

Even though they’re quite comical to look back on today, the four humours got their name from the Latin for “fluid” or “liquid”. According to practitioners of physiological theory in the European Middle Ages — I hesitate to call them “doctors” — the four humours that made up a person’s general personality, temperament and even physical characteristics were blood, phlegm, yellow bile and black bile. Ok, the first two I can get behind, everyone’s heard of blood and phlegm.

Yellow bile? I’ve thrown up before and I know we have bile ducts so I’m pretty comfortable that that’s a thing. Black bile though?

This is a bit confusing and as far as I can work out, what people in the past were calling “black bile” might have been some sort of sediment remaining from normal blood or maybe connected with all the gross boils from bubonic plagues. Why didn’t they choose another fluid that makes up the human body? Off the top of my head the one that makes the most sense is water — you know, as over half our bodies are made up of water, it comes out of our eyes and skin and we pee it out multiple times a day.

Guess that was a bit too obvious though and might have made the general populace realise that there was nothing to this four humours thing after all. Oh, sorry, spoiler alert — the four humours are no longer used as a medical diagnosis tool. If your doctor is talking about an imbalance in your black bile, find someone else, quick.

But anyway, the four humours weren’t really about the actual physical presence of these things, it was a bit more esoteric than that, with the fluids representing qualities of a person. If all four of your humours were in balance, congrats, you were fine. If you had too much blood in your humours, this was thought to give a person more “sanguine” characteristics, i.e. they were quite positive but it would also have presented as more ruddy facial features.

If you had an excess of phlegm, you would be “phlegmatic” or somewhat unemotional, with a pale complexion. An imbalance of yellow bile, also known as “choler” would indicate your angry personality and show in your jaundiced appearance and if your black bile, also called “melancholy” was out of whack, you’d be a sad soul wandering around with a dark complexion.

There were various different combinations of these humours with various different potential treatments. An excess of yellow bile could be treated with changing your diet or purging your system through vomiting which, if you ask me, would probably make you more aware of your yellow bile. Other popular methods for balancing the humours were using herbs and spices in your food, taking laxatives and bloodletting, either with leeches or by popping down to your local barbers for a session with their bloodletting razors which I’m sure were extremely well disinfected between patients.

We’re talking about this as this was basically what any medical professionals were working with at the time the glass men cometh. If someone had any kind of medical complaint from bad skin to epilepsy to cancer, it would be somewhere in the diagram of the humours and a treatment could be provided. While physicians at the time did believe they were on the right track here, they actually weren’t, so really any meeting you had with a doctor would have just been them stating what they guessed the problem was as related to the humours and then prescribing whatever the established remedy was at the time. While this probably worked ok for general sniffles and minor complaints, anything more serious was likely going to keep getting worse.

In the case of the glass men, doctors decided that this delusion must have been an excess of melancholia or black bile in the body. This does make some sense in that melancholia comes under the umbrella of depression and mental illness — if somebody is described as “melancholic”, it means they are gloomy, sorrowful or really sad. As black bile was thought to originate in the spleen and kidneys, one of the treatments was to purge it all out through the use of laxatives.

Also recommended was the eating of food with fragrant herbs and spices, and moist, warm foods to counteract the cold and dry classification of black bile. Melancholics were also warned to avoid many types of beans and nuts, tomatoes, eggplants and any type of fried food as this really upsets the digestive system of a bona fide melancholic. Obviously skipping the eggplant parmigiana isn’t really going to help in the treatment of a psychological disorder but bless them, at least they were trying.

In Molly Dowdeswell’s piece on The Collector.com, she says: “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.”

See, while they were skating round the edges of medical progress and did not really understand much about the finer or inner workings of the human body, it was already clear to people centuries ago that this kind of delusion was a symptom of a larger mental health issue. And while it’s been presented as some sort of genteel disease that only rich, intelligent people suffered from that allowed them to lounge around all day, suffer some of them did and horribly too, with some glass men even killing themselves to be free of the delusion.

Ian Hacking published a book called “Mad Travelers: Reflections on the Reality of Transient Mental Illnesses” in which he lists factors necessary in a time and place in society for a specific illness to first of all flourish, and then disappear. He names these vectors as “medical taxonomy, cultural polarity, observability and release”. I couldn’t read the bulk of the text of this book online so we’re turning to Carolyn Purnell writing for Psychology Today.com to go into more detail here.

One — “the disease must fit within existing medical models.” We can agree with this one as doctors of the time recognized glass delusion as pertaining to the excess of black bile in their four humours set-up.

Two: “cultural polarity (…) the illness must fall between two opposing elements of contemporary culture”. This leans into the stresses those in academia or the elite might have felt as they strived to keep up appearances, maintain their reputations or struggled to pursue new ideas.

Three: “A third vector requires that the disease is observable.” Glass delusion definitely fits here as well known and highly-placed people were noted to be suffering from it. The visibility of the disorder would have been a factor for the spread of it.

Four: “the illness, despite the pain it produces, should provide some release that is not available elsewhere in the culture in which it thrives.” Again glass delusion can be factored in here as it was almost seen as a status symbol, something only the rich and / or intelligentsia suffered from, even though, as we’ve said, more average members of society could have had it but we would never know. Maybe some sufferers could take a break from whatever was stressing them out while they waited for their bodies to go back to normal.

As we can fit glass delusion into these four vectors and can lump it in as a transient mental illness, this means that when society and culture moved on, there should have been no more cases of glass delusion. But is that strictly true?

I Like the Glass Onion as a Metaphor — Modern Cases

While this does seem to be mainly an issue of the past, glass delusion has managed to persist through to the modern era. Or modern-ish anyway. Dutch psychiatrist Andy Lameijin found references to glass delusion from a lecture in 1883, stating that a woman in a Scottish psychiatric institute believed her legs were made of glass.

He was also contacted about a case from the 1930s of another woman admitted into an institute, again believing her legs were made of glass. She was so scared of breaking them that she pulled a King Charles and wouldn’t let anyone near to help her wash or change her clothes. Her outcome was thankfully different though, as she recovered after being treated, although who knows what kind of treatment she was given almost a hundred years ago.

Lameijin was notified of yet another case from 1964, then a man claiming to be made of glass walked into his own clinic in Leiden although I’m not sure when that was. While Lameijin was excited to get to talk to this man, in my opinion, his delusion is not really the same. Back in the day, the general symptom of glass delusion was that a body part, whether a limb, an internal organ or indeed your whole self was made of glass and therefore at risk of shattering.

This case was more along the lines of the person feeling invisible, as though he were a pane of glass — people were looking through him rather than at him. To me, this is a different thing but hey, as we said at the start, not a psychologist.

Glass delusion is still appearing in works of fiction too, with Ali Shaw’s “The Girl With Glass Feet” from 2009 telling the story of a woman looking for a cure to stop her turning into glass from the feet up.

I think we can say with some certainty that, ok, while a few newer cases have popped up here and there, this was an illness of its time, a time when glass was seen as a magical element, when medicine was fumbling in the dark and strict social expectations were too much for some to bear. We can see other sorts of delusions comparable to glass delusion in other periods of history too. Strangely enough, it seems that believing you are made of, or turning into, the hot substance of the day is not merely a glass thing. Prior to everyone thinking they were made of glass, there were reported cases of people believing they were made of earthenware and, after glass delusion had died down, there were examples in the nineteenth century of people believing they were turning into concrete — the newest material on the block, so to speak.

But why was this even a delusion at all? Research has concluded that it’s a delusion of fragility, the inner psyche manifesting in an imagined physical form. Amelia Soth’s article on JSTOR.org notes: ”(…) the shattered vessel is a common Christian symbol for the fragility and limitation of the body. Maybe thinking of oneself as a structure of delicate glass was a reaction to the fragility of the human body, and the ease with which, in an instant, it could be shattered.”

The same could be said for earthenware, although concrete might be a tad more sturdy.

It could be said that glass delusion was a cultural phenomenon as well. As we’ve noted, it swept through the more notable levels of society and seemed mostly a European nobility thing. Glass delusion would not exist in areas of the world where glass was not in regular use as people would not equate it with the same meanings.

Things like this always remind me of a delusion called Koro where people believe their penises are shrinking into their bodies or disappearing, despite visual evidence that they aren’t. This is classed as a “culture-bound delusional disorder” meaning that it’s more prevalent and likely to spread amongst people in the same particular societal or cultural bracket.

While we can’t rule out examples of glass delusion appearing again in the future, it’s unlikely to reach the number of cases that were seen in the Middle Ages. These days, the most-agreed upon equivalent that I’ve seen is more of a persecution complex, or a feeling of being spied on, usually by the government which might bring with it a feeling of paranoia, helplessness and loss of autonomy. As we know we are actually being spied on a lot, from online data collection to CCTV cameras, this delusion probably isn’t going to go away anytime soon and as our reliance on technology continues, it seems like we might break into two camps — one that knows we’re being spied on and just shrugs it off, handing data providers all our information left, right and centre — I fall into this camp, by the way — and the other that starts guarding all their personal information to the max, and from which a healthy dose of paranoia might end up spiralling out of control. We’ve already seen this kind of thing happening, most recently with QAnon, Doomsday preppers etc. so I suppose it’s just part of the established cycle of the human experience.

End Fragments

To bring it back around to glass delusion again, even now the qualities of glass when related to the human body are promoted as being desirable. Obviously not the potential to get shattered into a million pieces, but I’ve clicked on many a link offering “glass like skin” or hair with a “mirror shine” so it is still seen as something of a positive attribute. Though the majority of the population will never again fall victim to the delusion they are made of glass, there are many other issues that could affect any one of us at any time so let’s huff a couple of breaths on the surface of this story and draw a quick heart or smiley face on it before it fades, our little acknowledgement of a strange story from the past.

Frequently Asked Questions

What is glass delusion?

Glass delusion is a psychological condition where individuals believe that parts or all of their body have turned into glass and are liable to shatter at any time.

When and where did cases of glass delusion primarily occur?

Cases of glass delusion primarily occurred in Europe between the 14th and 19th centuries, peaking in the 15th and 17th centuries.

What were the main symptoms of glass delusion?

The main symptoms included thinking that parts of the body, usually extremities or organs, had turned to glass, believing the entire body had turned to glass, thinking one had been turned into a glass vessel, feeling like one had ingested a glass object, or feeling invisible like a pane of glass.

How was glass delusion treated in the past?

Treatments ranged from indulging the sufferer until the delusion passed, keeping a safe distance or wrapping soft things around them, to using reverse psychology to prove that their body was not made of glass.

Who were some famous historical figures who suffered from glass delusion?

King Charles VI of France and Princess Alexandra of Bavaria are two well-known historical figures who suffered from glass delusion.

What was the significance of glass in the context of glass delusion?

Glass was seen as a magical and transformative substance, symbolizing both refinement and vulnerability. It was also associated with alchemical ideas of transmutation and was highly valued among the aristocracy.

How did the four humours theory relate to glass delusion?

According to the four humours theory, glass delusion was thought to be caused by an excess of black bile, or melancholy, which was associated with sadness and mental illness.

Are there any modern cases of glass delusion?

Yes, there have been modern cases reported, such as a woman in a Scottish psychiatric institute in 1883 and another in the 1930s, both believing their legs were made of glass.

What is the cultural significance of glass delusion?

Glass delusion was a cultural phenomenon that swept through the European nobility, reflecting the societal and cultural stresses of the time, particularly among the elite and intelligentsia.

How does glass delusion compare to other delusions of its time?

Glass delusion is similar to other delusions where people believed they were made of the hot substance of the day, such as earthenware before glass and concrete after glass.

Sources

• Original Decoding the Unknown video: Glass Delusion: Why Some People Think They are Made of Glass…
• Hero image source by Bernhard Holub / openverse, by-sa.