Flexible Roman Glass?

Did an ancient Roman inventor come up with flexible glass? That’s one possible interpretation of a curious anecdote told by several Roman sources.

A Roman drinking glass

The evidence

There is no archaeological evidence for flexible Roman glass; nothing like it has turned up in any excavation. All the evidence we have is literary, three mentions from various sources. Here is what we have (my own translations):

In the reign of Tiberius, a kind of glass was invented that was concocted in such a way that it was flexible, but the entire workshop of its inventor was destroyed so that the price of bronze, silver, and gold would not be brought down (a rumor that has for a long time had more repetition than credibility).

Pliny, Natural History 36.66

There was once an artisan who made a glass drinking up that was unbreakable. When he was given an audience with the emperor to show off his invention, he made the emperor hand the cup back to him, then hurled it to the stone floor. The emperor could not have been more alarmed. The man picked the cup up off the ground, and it was dented just like a bronze cup, but he produced a small hammer from his pocket and with very little effort he made the cup good as new. With this performance, he thought he was in the throne of Jupiter.

The emperor then asked: “No one else knows how to make glass like this, do they?”

Now, look what happened. When the man answered “No,” the emperor ordered him beheaded, because if knowledge of this invention got out, we would treat gold like mud.

Petronius, Satyricon 51

[An engineer comes up with a novel way of renovating a collapsing building, for which the emperor Tiberius jealously exiles him.] Later this man came to the emperor as a supplicant and deliberately let a glass drinking cup fall to the floor in front of him, and although the cup was somehow damaged, after rubbing and beating it with his hands on the spot he showed the emperor that it was unbroken. He was aiming to get himself a pardon, but the emperor ordered him executed.

Cassius Dio, Roman History 57.21

Could it be true?

There are a few reasons to think these stories might be true, if not in all details then at least in the most interesting one: that some Roman crafter figured out how to make a material that looked like glass but didn’t shatter like it.

The fact that we have this story from three different sources gives it some credibility, especially since two of those sources, Pliny and Petronius, are roughly contemporary with the emperor Tiberius under whom the unbreakable glass was supposed to have been invented.

Flexible kinds of glass exist today, but they are recent developments. It is unlikely that a Roman glassmaker, even if they had stumbled on the right chemical formula, would have had a furnace capable of high enough temperatures with precise enough control to have achieved the same result. It is more possible to imagine that a Roman artisan came up with something like modern plastic. Early plastics developed in the 1800s used materials that would have been available to the Romans, such as cellulose from wood, the resin of the sweetgum tree, and proteins derived from milk, eggs, and blood. Some of the plastics derived from these materials are translucent and flexible, and might have appeared to onlookers unfamiliar with their source as flexible glass.

Despite these considerations, though, there are much stronger reasons to think that nothing like flexible glass was ever created in antiquity.

Probably not

First of all, we have to look at our sources critically. None of them is very good as evidence. Pliny straight out tells us that he doesn’t believe the story he is relating. Petronius puts the story into the mouth of a boorish and narcissistic fictional character, far from a reliable narrator. And Cassius Dio was writing about two centuries later and seems to have garbled this story with the tale of a later emperor, Hadrian, and his jealousy of a famous architect. Although it is interesting that we have versions of this story from three different sources, all that means is that, as Pliny notes, it was a tale widely told, not necessarily that there was any truth to it.

The fact that this story is connected with Tiberius also points to it being unreliable. Pliny, Petronius, and Cassius Dio were all part of the Roman elite, who generally disliked Tiberius. As the second emperor of Rome after the beloved Augustus, Tiberius had big sandals to fill and little of his predecessor’s charisma and social grace. The accounts of Tiberius as emperor that have come down to us describe him as tactless, cynical, cruel, and prone to paranoia. He also ruled Rome during a time of economic hardship, and his pragmatic concern for financial stability (including worrying about things like the prices of commodities and the steadiness of the gold and silver supply) came off as small-minded stinginess to the rest of the Roman upper crust. The idea of Tiberius responding to a wondrous new invention by destroying both it and the inventor appealed to existing prejudices about him, which helped the story spread. Romans like Pliny and Petronius already believed that Tiberius was cruel when he should have been magnanimous, tight-fisted when he should have been generous, and quick to apply violence to those who did not deserve it. The story of the wondrous glass cup not only made these qualities manifest, it served as a cautionary tale about the foolishness of such behavior. It was, in short, a good story, and good stories spread easily even when they aren’t true.

If there is any kind of truth behind the tale, it may be something less revolutionary. Glassmaking is a skilled art, and in antiquity it practitioners carefully guarded their secrets. To an uninitiated observer, the malleability of hot glass in a glass-blower’s workshop may have seemed quite wondrous, and the story may have spread from there without the crucial understanding that glass only flows so easily when it is fresh from the furnace. Additionally, around the time of Tiberius, new kinds of mold-blown glass were coming onto the Roman market that imitated the shapes of metal vessels. To the average Roman aristocrat shopping for luxury housewares, the idea that a material might exist combining the translucency of glass with the malleability of metal might not seem so far-fetched. If these ideas were already circulating in Roman literary circles, it is not strange to imagine that someone put them together with the existing negative perceptions of Tiberius and concocted a “What if” story that took on a life of its own as gossip and political mudslinging.

In the end, it is unlikely that any Roman artisan ever figured out how to make flexible glass. As interesting as the story is, it tells us more about the perception of Tiberius than it does about any fabulous ancient discoveries.

Further reading:

Champlin, Edward. “Tiberius the Wise.” Historia Bd. 57, H. 4 (2008): 408-425

Keller, Vera. “Storied Objects, Scientific Objects, and Renaissance Experiment: The Case of Malleable Glass.” Renaissance Quarterly 70, no. 2 (2017): 594-632.

Stern, E. Marianne. “Ancient Glass in a Philological Context.” Mnemosyne 4th ser. 60, f. 3 (2007): 341-406.

Image: Roman drinking glass (not flexible), photograph by Marie-Lan Nguyen via Wikimedia (Domvs Romana, Mdina, Malta; 1st c. BCE-2nd c. CE; glass)

History for Writers looks at how history can be a fiction writer’s most useful tool. From worldbuilding to dialogue, history helps you write.

A Contradictory Coin

Two faces of an ancient Roman coin, one showing a bearded man wearing a radiate crown, the other showing a young men wearing a wreath.



Palmyrene Antoninianus, photograph by Classical Numismatic Group via Wikimedia (270-272 CE; bronze and silver)

What’s so contradictory about this coin? Well, there’s a story behind it.

In the third century CE, the Roman Empire wasn’t doing well at all. Between 235 and 284, the empire suffered civil war and political chaos as numerous general claimed the imperial title with the backing of their troops, only to be assassinated and replaced with another general. At the same time there was an economic collapse and an outbreak of deadly disease that depopulated the great cities of the Mediterranean.

In this fifty years of crisis, the emperors were mostly concerned with securing their own power and fighting off rivals. People looked to more local powers to handle the ordinary business of governance. With such chaos and weakness at the top, some of these local powers began to operate as effectively independent states.

One such state was the empire of Palmyra. Palmyra was a city in the eastern Mediterranean, in what is today Syria. It had long been an important stop on caravan routes that connected the Mediterranean with Mesopotamia and India beyond. The Palmyrene noble Odaenathus helped to support the Roman position in the region during a flare-up of conflicts with the Parthian Empire to the east. With weakness at the top of the empire, Odaenathus began to rule Palmyra with more and more independence over the course of the 260s. After his death in 267, his wife Zenobia, ruling on behalf of their young son Vaballathus, began an ambitious campaign of conquest that made Palmyra the ruling city of a de facto empire covering much of the Roman East.

While effectively operating as an independent power, Palmyra maintained a show of loyalty to the Roman Emperor at the time, Aurelian. In the early 270s, Zenobia issued coins like this one, bearing the image of Aurelian on one side and Vaballathus on the other. The text of the coin names Aurelian as emperor and calls Vaballathus only a general of the Romans. Since coins could circulate more widely than most other works of public art, these coins represented one of Zenobia’s best efforts to convey the message to Aurelian that she and her son were still loyal.

But the very existence of these coins belies the message they send. The minting of coins was an imperial prerogative, one closely tied to the power of the emperor himself. Rome allowed some of the cities under its rule to mint their own low-value bronze coinage for local trade, essentially small change to make it easier for people to do their day-today business in the market. Palmyra evidently had the right to mint such coins, although surviving evidence suggests that the Palmyrenes had never exercised that right on any large scale.

This coin is different. It is the type of coin known to scholars today as an “Antoninianus.” (We don’t know what, if anything, ancient people called them.) An Antoninianus was a high-value coin typically made of a combination of bronze and silver. Its face value was equivalent to several days’ pay for a legionary (although extreme inflation in the third century seriously eroded the coins’ actual value), and they were largely minted by the emperors to pay the troops who had put them into power. Coins of such value had a strong historical connection to the recruitment and pay of armies.

By minting coins of this type, Zenobia effectively declared her intention to lead armies independently of the Roman emperors. No matter what image she put on the coins, the very act of minting them was tantamount to announcing a rebellion.

Aurelian was not fooled by the display of loyalty. In 272 he attacked Palmyra, captured Zenobia, and reconquered the territory she had claimed. After another outbreak of rebellion in Palmyra the next year, Aurelian captured the city and destroyed it.

An object as seemingly simple as a coin can have complicated and even contradictory intentions behind it.

History for Writers looks at how history can be a fiction writer’s most useful tool. From worldbuilding to dialogue, history helps you write.

Quotes: I Wouldn’t Want to Suddenly Make a Fool of Myself

How nice that you feel so sure of my affections.

I wouldn’t want to suddenly make a fool of myself

Go ahead, chase that cheap, wool-spinning

whore rather than Servius’ daughter Sulpicia.

I have people who care about me, and their greatest worry

is that I might fall into bed with some worthless nobody.

– Sulpicia, Poems 4

(My own translation)

Sulpicia is among the few female writers whose work has come down to us from antiquity. She was a Roman poet writing in the late first century BCE. Her surviving poems chart a tempestuous love affair with one Cerinthus. Like the lovers described in poetry by her male contemporaries, we cannot be sure whether Cerinthus was a real person or just a literary invention.

Sulpicia’s poetry relates in interesting ways to the major philosophical movement among Romans of her time: Stoicism. Stoicism was an originally Greek school of thought that emphasized emotional steadiness through the ups and downs of life. This idea appealed to Romans, who traditionally valued discipline and dispassionate self-control. Many Romans among the elite espoused versions of Stoic philosophy as a guiding principle.

Controlling one’s emotions first requires observing and understanding them. This is where Sulpicia’s poetry fits in. Her poems are like little gems of precisely observed emotion. This one captures the cold, controlled anger that comes of holding in a rage that is about to explode. Another poem expresses the exasperation of a young person at well-meaning but clueless relatives.

While other Romans were exploring Stoicism as a philosophical idea, Sulpicia was turning it into art.

Serving exactly what it sounds like, the Quotes feature excerpts other people’s thoughts.

Slavery Was Always Wrong

Slavery was integral to the societies and economies of the ancient Mediterranean, so much so that discussing almost any topic in ancient history will end up touching on it at some point, and as historians we do not always take the time to address slavery as an institution in itself. The practice of slavery in Greece and Rome also differed from the modern American version in significant ways, which we often have to explain. The combination of these facts can sometimes leave the impression ancient slavery was in some way less wrong than modern slavery.

So this is me as an ancient historian taking the time to say: it was not. Slavery is, was, and has always been wrong.

The practice of slavery—that is, treating some people as possessions who have no rights to autonomy or claims to humanity and who can be exploited for labor without their consent and without compensation—is common across many cultures in history. Almost every pre-modern society (and many societies in the modern period) complex enough to have a division of labor had some mechanism for forcing a particular class of people to labor against their will. In many cases, this class of people came from outside that society or were the descendants of people who had, but local people could be among the exploited as well. Cultures that did not practice slavery have existed in history, but they are rarities. Just as different cultures in history varied widely in their ways of life, they also varied in how they practiced slavery, but inherent in all slave systems is the violence—whether actual or implicit—that comes of treating people as things.

In all slave societies, those who benefited from the exploitation of others generally found ways of justifying the practice. The voices of the rich and powerful dominate the historical record, especially as we look farther back in time. The voices of enslaved people themselves are often missing from the sources (at least until more recent centuries), and we should not suppose that they shared the opinions of the people who were exploiting them. If our image of ancient slavery is not one of violence and horror, that tells us more about whose stories we are hearing than about the actual experience of slavery. We are never on solid ground making judgments based on what the rich and powerful think is okay for them to do to other people in order to stay rich and powerful.

Slavery played an important role in the economies of both ancient Greece and Rome, more so than in some of the other cultures they lived alongside. Greeks were major players in Mediterranean trade for centuries, and trafficking in enslaved people was a significant part of that trade. The islands of Delos and Rhodes were major centers of the trade in enslaved people, as documented by numerous inscriptions found in both places left by the traders. Slavery was particularly important in the Roman economy because Rome was an expansive empire. Enslaving war captives was one of the most direct ways of profiting off the near constant warfare that marked the growth of the empire.

There are important ways in which the practice of slavery in the ancient Mediterranean was different from that in modern-period America. For example, enslaved people were not distinguished by race from those who exploited them. Greeks and Romans did not have a concept of race as we understand it, but even so, enslaved and free were not distinguishable by physical appearance (a point made clear by numerous legal and literary sources about enslaved people passing themselves off as free). In Rome, there was a custom of granting freedom to some enslaved individuals after a period of time. These freed people gained some legal status in Roman society (either citizenship or a lesser status as “Latins,” depending on the time period) and they and their descendants could integrate themselves into Roman society.

Still, the fact the Greek and Roman slavery was different does not make it less wrong. The exploitation, violence, and dehumanization inherent in slavery are always wrong. The experiences of individuals may vary between times and cultures—and even within the same time and culture—but those variations are not a defense of slavery, neither as a general practice nor in any particular case.

There has never been a time when slavery was morally defensible. It has always been wrong.

History for Writers looks at how history can be a fiction writer’s most useful tool. From worldbuilding to dialogue, history helps you write.

A Roman Boat Trip to Nowhere

Most of us aren’t doing a lot of traveling these days, what with the pandemic restrictions. Some people are missing the travel experience so much they’re paying for flights to nowhere, but it’s good to be reminded that travel can also be a real pain—uncomfortable accommodations, bad food, rude fellow passengers, awkward schedules, and the like.

Travel could be just as difficult in the past, too. Here’s the Roman poet Horace’s description of an unintentional canal boat trip to nowhere to remind you of what you’re (not) missing.

[…] An hour went by in taking fares
and hitching up the mule. The vile marsh midges and frogs
kept sleep at bay; all the while a boatman, sloshed on cheap wine,
competed with a passenger in crooning to absent
girlfriends. At last, worn out, the passenger went to sleep
and the lazy boatman hitched the mule to a rock
to graze, then flopped down and snored.
When morning dawned we realized the old tub
wasn’t moving, not until some hothead jumped up and gave
the mule and boatman both a good thrashing about the head and hindquarters
with a willow switch. […]

– Horace, Satires 1.5.13-23

(My own translation)

Enjoy the pleasures of just staying home!

Serving exactly what it sounds like, the Quotes feature excerpts other people’s thoughts.

Now It Is Time to Drink!

If you’re feeling celebratory today, here’s a little verse from the Roman poet Horace to put you in the right mood. Horace was celebrating the defeat of Marcus Antonius in the last phase of the Roman republic’s long-running civil wars of the first century BCE (although, for political reasons, focusing most of his scorn on Antonius’ Egyptian ally, Cleopatra). But you can drink and dance for whatever is making you happy today!

 Now it is time to drink! Now with liberated feet
dance upon the earth! Now the sumptuous
feast of the gods
can be spread, my friends!

Before this, the time was not right to bring the good Caecuban wine
up from the ancient cellars, not while the insane queen
schemed to bring death and ruin
to the Capitol and our state

with her foul throng of thugs,
drunk with vain hopes
of sweet
victory.

– Horace, Odes 1.37.1-12

(My own translation)

Enjoy!

Serving exactly what it sounds like, the Quotes feature excerpts other people’s thoughts.

Visualizing the Roman Emperors

Sometimes, putting information into a visual form helps you make sense of it. I’ve been studying, writing about, and teaching the history of the Roman Empire and its emperors for more than two decades now, but taking my knowledge and making it visual helped me grasp the significance of some of the long-term patterns I’ve know about for so long. In this chart, you can see the stumbling uncertainty of the early empire, the stability of the second century, the chaos of the third century, and the complexity of the late 200s to early 300s.

(It’s a big image; you have been warned!)

Continue reading

Bardcore: Now in Classical Latin

Most of the bardcore versions I’ve seen are in plain modern English, some in ye olde faux medievale Englisshe, and some even in Old French. But so far there seems to be only one in Classical Latin: “Smells Like Teen Spirit”.

Smells Like Teen Spirit Cover In Classical Latin (75 BC to 3rd Century AD) Bardcore by the_miracle_aligner on YouTube

Oh, yeah! LOL!

An occasional feature on music and sound-related notions.

Arcanus, Miles Arcanus

The Roman fort at Vindolanda in northern Britain, established in the first century CE close to where Hadrian’s Wall would later be built, has yielded an amazing variety of documents written on wooden tablets. These sorts of tablets were used for everyday writing in parts of the Roman world for things like personal letters and shopping lists. I’ve talked about a couple of the finds from Vindolanda before (here and here), but today I’ll turn to one of the more perplexing finds from the site.

Vindolanda tablet 162 is a small strip of wood with two words on it: MILES ARCANU[S]. Miles is clear enough: it means ‘soldier,’ which you would have found plenty of in Vindolanda. Arcanus is more of a puzzle. It can be a personal name, although it’s not common, and it could have been the name of a soldier stationed at Vindolanda. The usual word order in that case, though, would be Arcanus miles, ‘Arcanus, the soldier.’ But as a word on its own, arcanus means ‘secret’ or ‘hidden.’ The clearest reading of this tablet is: ‘Secret soldier.’

What is a secret soldier? The answer may lie in a mention from the Roman historian Ammianus Marcellinus in his Res Gestae, written in the fourth century CE, referring a group in Britain called the areani. The word areani is itself a puzzle: it exists in no other recorded Latin text. It would seem to mean ‘people of the bare lands’ or possibly ‘people of the sheepfolds,’ and might be a reference to people who lived in the wilderness near the Roman frontier. One widely (though not universally) accepted suggestion, however, is that areani is a medieval scribe’s mistake for arcani, ‘secret ones.’

As for who these secret ones were, Ammianus gives us a pretty clear idea:

Their duty was, by hastening far and near, to keep our generals informed of disturbances among nearby tribes.

– Ammianus Marcellinus, Res Gestae 28.8.3

(My own translations)

This account pictures the arcani/areani as scouts or spies who operated outside the frontiers to gather intelligence on potential military threats. One product of their work may also be preserved at Vindolanda, a fragmentary tablet which seems to preserve a piece of a report on the fighting capabilities of the native Britons:

the Britons are naked [or lacking armor?]. They have lots of cavalry. The cavalry do not use swords. The Brits do not take position to throw javelins.

– Tabulae Vindolandenses 164

We don’t know how widely the arcani existed in the Roman Empire, at least as an organized group. They are documented only in Britain and might have been a peculiarity of that frontier. One of Rome’s weaknesses as a world power was a lack of any centralized gathering of intelligence on the frontier and foreign peoples, and the emperors were often poorly informed as to what was happening at the edges of their empires. On the local level, though, Roman commanders on many parts of the frontier made use of scouts and patrols to keep an eye on the border regions that fell under their purview.

If this kind of scouting is what the Miles arcanus text refers to, why would the text itself have been written? Surely it isn’t a very sly spy who carries around a tablet saying: “I’m a spy.”

The dangers that this particular secret soldier faced, though, did not necessarily all come from the British side of the border. Roman soldiers on frontier patrol had a habit of abusing their power for personal gain, roughing up the locals and shaking down merchants. Another fragmentary letter from Vindolanda appears to be the draft of a complaint from a merchant to the provincial governor about just this sort of bad behavior by a soldier (the beginning is damaged, so we know less than we would like about the event in question):

… he beat me further until I would either declare my goods worthless or else pour them away…. I beg your mercy not to allow me, an innocent man from abroad, about whose honesty you may inquire, to have been bloodied with rods like a criminal.

– Tabulae Vindolandenses 344

Under such conditions, someone whose business required them to travel around beyond the frontier, probably blending in with the locals, but also report back regularly to a fort full of Roman soldiers, might be well advised to carry around something to prove that he was who he said he was: a spy for Rome.

Image by Erik Jensen

History for Writers looks at how history can be a fiction writer’s most useful tool. From worldbuilding to dialogue, history helps you write.

Quote: Something that You Have Longed For Without Hope

If something happens that you have longed for and desired without
hope, it is a blessing to your soul.
So it is a blessing to us, more precious than gold,
that you long for me again, Lesbia.
You long for me without hope; you bring yourself back
to me. What a red-letter day!
Who leads a happier life than mine? Who can say
that life has given him a greater gift?

– Catullus, Poems 107

(My own translation)

I think a lot of us now know what it is like to long for something almost without hope, even if it is not for the return of a former lover. One thing I have longed for this past spring is the long days of summer when the sun lingers in the sky and we can enjoy warm evening breezes.

Whatever it is you are longing for now, I hope this summer brings it to you.

Serving exactly what it sounds like, the Quotes feature excerpts other people’s thoughts.