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The glass delusion - a belief in human frailty or a desire to transcend human existence? Source: Creative Commons

Glass Delusion: Bizarre Medieval Affliction Left People Shattered


There is a story dating back to the 1960s about a man who overdosed on LSD and became permanently insane. In his insanity, he believed himself to be a glass of orange juice. He was afraid to lie down, lest he be spilled, or go to sleep, lest someone drink him. This story is likely little more than an urban legend, but it parallels a real delusion that many people suffered with throughout the early Modern period from the 14th century into the 19th century. This was the delusion that part, or all, of their body was made of glass. Some medical documents dating to that period also describe cases where patients believed that they were specific glass objects, such as vases or pitchers. The cause of this mysterious and widespread glass delusion is still a subject of debate today among scholars, though it appears to be related to a fear of fragility and possibly a desire to transcend normal human existence.

King Charles VI, the Most Famous Case of Glass Delusion

The most famous case of glass delusion is probably that of King Charles VI of France. Charles VI (1368-1422) ascended the throne in 1380 at the age of about 11, but he did not begin to rule independently until 1388. Up until then, he had been under the supervision of his uncles.

He was a promising young monarch at first. He implemented reforms to improve the bureaucracy and reduce corruption. He also involved himself in papal politics. At the time, there were two popes, a pope in Rome and a pope in Avignon, France. The two popes were in rivalry with one another over who was pope and who was anti-pope.

Charles VI approached Clement VII, the pope in Avignon, and discussed installing him as pope in Rome. Before he could go forward with this political move though, Charles VI became ill in 1392 and had what historians believe was his first schizophrenic episode. Charles VI came to believe that he was made of glass and he would not move without wearing reinforced clothing. This would continue intermittently for the rest of his life.

Madness of Charles VI: crossing the forest of Le Mans on an expedition against Pierre de Craon, the king, brandishing a sword, mistakes the members of his retinue for enemies and attacks them. (Public Domain)

Madness of Charles VI: crossing the forest of Le Mans on an expedition against Pierre de Craon, the king, brandishing a sword, mistakes the members of his retinue for enemies and attacks them. (Public Domain)

Aristocrats with Glass Buttocks

Charles VI is the most famous case, but he is only one of many aristocrats and scholars who suffered from this strange glass delusion over the past five or six centuries. Another account, told by two royal physicians from the late 16th and early 17th centuries, tells of an anonymous nobleman who believed himself to be made of glass and confined himself to a straw bed to protect himself from shattering. He specifically believed that he was a glass vase.

One day, his physician, frustrated from unsuccessfully trying to talk him out of his delusion, set the straw bed on fire and locked the nobleman in his room. When the man began to bang on the door, begging his physician to open it, the physician asked why he did not shatter with all the banging if he was made out of glass. This is said to have cured his delusion.

There are similar reports of men who believed that they had glass buttocks, which they were afraid would shatter if they sat down without cushioning. In one case, an exasperated physician gives a man suffering from this specific delusion a thrashing upon his buttocks. Afterwards, the physician tells him that the pain he feels must be from “buttocks of flesh.”

This delusion became much less common in the 19th century. One of the last classic examples of the glass delusion was Alexandra Amelie, the daughter of Ludwig I of Bavaria. In the 1840s, when she was a young woman, Alexandra came to believe that she had swallowed a glass piano in childhood. This led her to believe that she had to walk around carefully to avoid causing it to shatter.

Princess Alexandra of Bavaria (1818-1875). (Public Domain)

Princess Alexandra of Bavaria (1818-1875). (Public Domain)

Although cases of the glass delusion have been quite rare since the 19th century, there were a few cases in the 20th century. These cases were much more obscure and did not involve high profile political or cultural figures like earlier cases.

Possible Causes for the Glass Delusion

Scholars of the time attributed the mental illness to the, now discredited, notion of melancholy. Melancholy was a disorder believed to primarily affect nobles and scholars. The reason for this diagnosis was likely that so many of the recorded patients were nobles and intellectuals. Interestingly, many of the people with these delusions were otherwise highly intelligent and creative individuals.

This is exemplified in a short story by the Spanish writer Miguel de Cervantes, written in the 17th century, The Glass Graduate. In this story, an intellectually gifted lawyer is given a love potion that causes him to go mad and believe that he is made of glass. He does not let anyone come near him. He also sleeps on a bed of hay, only eats fruit, and only drinks water from a river by cupping it in his hands.

Tomas Rodajas. (Rosmairy/CC BY SA 4.0)

Tomas Rodajas. (Rosmairy/CC BY SA 4.0)

He does this all because he believes he is made of glass and must protect himself from shattering. Despite his delusion, he is still an intelligent and functional individual, who even draws crowds with his wisdom and sense of humor.

The glass delusion mirrors other delusions documented by physicians where people believed that they were made of clay, that they were headless, or that they were made of butter. All these delusions were also attributed to melancholy.

Melancholy dates at least back to Galen, Hippocrates, and other classical physicians who believed that disease was caused by an imbalance of the four humors. Melancholy, specifically, was blamed on an imbalance of black bile.

A woodcut from ‘Physiognomische Fragmente zur Beförderung der Menschenkenntnis und Menschenliebe’ (1775-1778) by Johann Kaspar Lavater. Phlegmatic and choleric (above), sanguine and melancholic (below). (Public Domain)

A woodcut from ‘Physiognomische Fragmente zur Beförderung der Menschenkenntnis und Menschenliebe’ (1775-1778) by Johann Kaspar Lavater. Phlegmatic and choleric (above), sanguine and melancholic (below). (Public Domain)

The explanations of late Medieval and early Modern doctors and scholars are no longer accepted by modern historians, but the reports of early Modern physicians are still considered illuminating. Two common themes of the glass delusion are the fear of being fragile and the belief that the body is transparent.

An example of the latter symptom is an instance in literature when a man tells his companion that he realized he was made of glass when he held up his hand to the sun and realized that it was transparent, like glass.

Glass and the Early Modern Mindset

The glass delusion was surprisingly widespread among the upper classes of late Medieval and early Modern Europe. It was common enough to be mentioned by several major physicians, scientists, and philosophers, including Rene Descartes. The reason for why it was so widespread is mysterious. Equally mysterious is why it almost completely disappeared after the 19th century, except for a handful of obscure cases.

Understanding why the glass delusion was so common in the late Medieval and early Modern periods would be illuminated by understanding what glass was to the people of that era.

In the late Middle Ages, glass was considered a very fragile material. There are accounts in which people who were particularly thin skinned were mockingly referred to as being “made of glass.”

A glass wine bottle dating from 1690-1700 AD. (The Portable Antiquities Scheme/CC BY 2.0)

A glass wine bottle dating from 1690-1700 AD. (The Portable Antiquities Scheme/CC BY 2.0)

The fear of fragility behind the Medieval glass delusion is explored extensively by writers of the early Modern period. What is interesting is that, during the early Modern period, it was not uncommon for scholarly and popular literature to compare the human body to glass or other fragile vessels. Biblical and ancient literature have many examples of figures or objects made of glass or other breakable material, such as earthenware, where the material is used as a metaphor for the frailty and impermanence of the physical body.

The human body was considered by many philosophers and theologians at the time to be a fragile, temporary vessel for the soul that would soon be discarded for a new resurrected body or a state of pure non-corporeal existence.

This association of fragility with the human body and the material of glass may have given the delusion a sort of psychological credibility in the minds of early Modern Europeans. Sufferers of the glass delusion may have been acutely aware of their fragility and in pursuit of a way to cope with it.

Being nobility, in most cases, they may also have felt that they were constantly under the watch of others. This may be pure speculation, but the desire that many people with the glass delusion had to separate themselves from others for their own perceived safety, lest they be shattered, may have been an expression of a desire to be left alone.

Transparency, the Body, and the Soul

The second symptom, belief that they were transparent, was talked about less often in the early Modern period, but it also has connections to late Medieval and early Modern philosophy regarding the relation between the body and the soul.

Some philosophers in the Middle Ages and the early Modern period compared the mind to the eyes. Just as the eyes had to be clear and transparent to perceive light, the mind also needed to be transparent to perceive “light,” the light of truth in this case. The flesh was often seen as inhibiting the ability of the soul to correctly perceive reality. Thus, just as material around the eye needed to be transparent, the mind also needed to be in a “transparent” medium. This connection between transparency of vision and transparency of mind, or soul, might be reflected in the literature of the era.

Miguel de Cervantes’ character, Tomas Rodajas, declares that his soul can conduct itself more efficiently in a glass body. Tomas seems to think that a body made of glass is a superior vessel for the rational soul than then a vessel of flesh. It is unclear, however, what property of glass makes it superior in the character’s opinion, though it could be that he is referring to the transparency of glass.

Tomas’ statement is particularly interesting because of another property of transparent glass. It was a relatively new and innovative material at the time. Technological innovations always elicit fascination and fear. People are drawn to them, while also being fearful of them because they are unfamiliar and unpredictable. It makes sense that glass would be the subject of common delusions because of the mystique that transparent glass had in the early Modern period as a technological innovation.

It is also interesting to note that it was in the 16th and 17th centuries, during the peak of the glass delusion, that instruments with glass lenses, such as telescopes and microscopes, first came into widespread use.

Early depiction of a ‘Dutch telescope’ from the “Emblemata of zinne-werck” (Middelburg, 1624) of the poet and statesman Johan de Brune (1588-1658). (Public Domain)

Early depiction of a ‘Dutch telescope’ from the “Emblemata of zinne-werck” (Middelburg, 1624) of the poet and statesman Johan de Brune (1588-1658). (Public Domain)

Has Glass Delusion Transformed to Suit Our Times?

This pattern is also seen with other innovative materials. During the 19th century, as cases of the glass delusion declined, there was an emergence of cases where people had the delusion that they were made of concrete, an important construction material of the Industrial Revolution. In modern times, this may be reflected in delusions people have that the government has inserted a microchip into their brain or that they are being constantly monitored by computers.

Tomas, in The Glass Graduate, feared being made of glass because he thought it made him fragile, but he also appears to have considered his glass body superior to his fleshly one. He believed that his soul was able to act through the material of glass more easily than it was able to act through the material of flesh. In other words, his glass body was not just a curse but could also be an enhancement.

Does this have a parallel in how emerging technologies are seen today? In the same way that some people in the early Modern period were (albeit irrationally) afraid of losing their fleshly bodies and becoming glass, many people today fear the prospect of their biological organs being replaced by cybernetic implants. At the same time, cybernetics offers the hope of human enhancement with greater intelligence, an indefinite lifespan, and other benefits.

A cybernetic heart. (paul /Adobe Stock)

A cybernetic heart. (paul /Adobe Stock)

In the same way, people of early Modern Europe may have both feared and desired the possibility of being made of something other than flesh. They feared it, perhaps because it made them less human and limited their lifestyle choices. At the same time, they longed for it because it would allow them to escape the limitations of their current bodies of flesh.

It is possible that an impulse both very ancient and very modern is coming out in this otherwise bizarre and inexplicable delusion.

Top Image: The glass delusion - a belief in human frailty or a desire to transcend human existence? Source: Creative Commons

By Caleb Strom


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Just lead. Good ole lead. 

or it was the effect of poisoning with Ergotamine ( the precursor for LSD.

Caleb Strom's picture


Caleb Strom is currently a graduate student studying planetary science. He considers himself a writer, scientist, and all-around story teller. His interests include planetary geology, astrobiology, paleontology, archaeology, history, space archaeology, and SETI.

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