‘The unhappy man imagined that he was entirely made of glass.’
The Glass Graduate, Miguel de Cervantes, 1613
One of the most intriguing ailments in the history of psychiatry is the ‘glass delusion’. For over two hundred years scores of erudite Europeans believed all or part of their body to be made of glass and in need of protection from shattering. Who suffered from this fear? Why did they believe they were made of glass? What do modern scholars say about this curious affliction?
Charles VI of France: The king who believed he was glass
On a hot August day in 1392 the young French king, Charles VI (1368-1422), was marching through a forest near Le Mans, northwest France, with a company of knights and retainers, on a mission to Brittany.
Champing at the bit to reach the enemy, the 23-year-old monarch’s manic energy reached such a heightened state that when a page boy dropped a lance the loud clang threw the Gallic ruler into an uncontrollable frenzy. Blindly swishing and swashing his sword around, he managed to kill five of his own knights before being pulled from his horse and restrained. Charles’s first recorded psychotic episode, the king’s chronicler the Religieux de Saint-Denis described it as a manifestation of a fear of persecution, delusion, and involuntary violence.
Dubbed ‘Charles the Mad’, at times he reportedly failed to recognise his wife and children and would dash madly around the palace. In November 1405, Charles who after refusing to wash for five months was covered in infected sores and lice was forcibly bathed at the behest of the king’s physician.
Charles also had the peculiar ‘glass delusion’.
Sufferers of glass delusion tended to believe their head, arms or buttocks were composed of glass. Scholar Gill Speak, in his famous 1990 paper, ‘An odd kind of melancholy: reflections on the glass delusion in Europe (1440-1680)’, described Charles VI as ‘possibly the first case of a man believing his whole body to be made of glass’.
The future Pope Pius II wrote of Charles VI:
‘His malady grew worse every day until his mind was completely gone. Sometimes he thought he was made of glass and would not let himself be touched. He had iron rods put into his clothing and protected himself in all sorts of ways so that he might not fall and break.’
Where did the glass delusion come from?
In classical and early medieval texts there are records of people who were described as or believed themselves to be made of earthenware, and these were typically linked to Biblical references to pottery and men of clay. (‘As the vessels of a potter shall they be broken to shivers.’).
In the second century AD, Rufus of Ephesus wrote of a man who thought he was a large piece of pottery. These precursors to the sufferers of glass delusion have been dubbed ‘Earthenware Men’.
The ‘Glass Men’ were a continuation of this literary and medical tradition, an updated delusion for the glass age. First recorded in a 1561 medical text by Dutch doctor Levinus Lemnius (1505-1568), glass delusion was a condition that existed primarily in the 15-17th centuries in Europe. This neurosis belonged to a wider category of mental illness called ‘scholar’s Melancholy’, a ‘high’ malaise particular to the 15th-17th centuries. The learned men who endured this ‘melancholia’, the ‘black bile’ of the Greeks, would be bed-ridden for long periods of time, experience confusion, suffer delirium, and be severely depressed.
Some cases of glass delusion saw the subjects believing themselves to be glass vessels, such as ‘urinals’, and some believed themselves to be trapped inside glass bottles. Life and art in Renaissance Europe imitated one another, as real-life cases of glass delusion apparently coincided with a rich literary tradition of ‘Glass Men’, such as in Cervantes’s story.
The glass menagerie: Selected cases
In The Optick Glasse of Humors of 1607 Thomas Walkington (d. 1621) describes a real case of a Venetian man who believed his shoulders and backside to be made of glass, and therefore had a fear of sitting down. This ‘fool’, as Walkington calls him, never left the house out of a fear that a glazier would make him into a window.
A 17th-century Paris doctor reported successfully curing a similar complaint. Treating a man who also believed he had a glass behind, the physician proceeded to beat the man’s rear end severely. Thus, he demonstrated to the patient that his stinging buttocks were proof that they were not made of glass but from sensitive flesh. Princess Alexandra of Bavaria (1826-1875) suffered from the false belief that inside her body was a grand piano made of glass.
Dutch Golden Age poet and theologian Caspar Barlaeus (1584-1648) was a famous ‘melancholic’ who suffered from four delusions: believing himself to be made of straw; a persecution complex; a conviction that he was made of butter; and thinking that he was made of glass. Gill Speak refers to Barlaeus’s glass delusion as ‘unsubstantiated’, however.
Is there a modern explanation?
One historian of psychiatry has in recent years suggested that materials-based delusions throughout history have been unconsciously influenced by new technology and substances.
Glass has been around for thousands of years, but transparent glass was something quite new at the height of the glass delusion. In the 15th century, Venetian glassmaker Angelo Barovier invented ‘cristallo', a clear, colourless glass. It was relatively uncommon and seen by many as wondrous and magical.
Before the Glass Men, there were the aforementioned Earthenware Men, and the 19th century even saw cases of Concrete Men who believed themselves composed of the new material of the age.
Psychiatrists have also contended recently that the glass delusion could be related to a fear of physical contact and a desire to distance oneself from other people – an insistence of the sufferer that they may ‘shatter’ upon being touched was a delusional way of creating for them an effective physical barrier.
Obsessive paranoia that they make break into pieces was for sufferers a genuine fear that they were made of glass and therefore vulnerable to breaking.
The bi-polar king
In the case of Charles VI, a 2018 study by a team of French psychiatrists argued that Charles VI may have had bipolar disorder. Their reasoning is based on the king having recurrences of manic-depressive episodes of varying severity, interspersed with asymptomatic periods, which is a characteristic of this kind of disorder.
The French king suffered 56 mental health episodes according to one 2017 scholarly analysis gives.
Did the glass delusion die out?
The prevalence of glass delusion dropped off considerably after the late 17th century. There were reportedly a handful of genuine cases in the late 19th century, in Paris and in Edinburgh. Records of isolated cases of the delusion were found dating back to the 1930s in the Netherlands, and in recent years a Dutch psychiatrist has stated that he has treated an ‘authentic case’ of glass delusion in his hospital in Leiden.