Saturday, 3 November 2012

Did the Romans really invent "flexible" glass?

A relatively unknown, yet intriguing myth about Ancient Rome tells us about the Roman emperor Tiberius executing a glassmaker for allegedly inventing something called 'vitrum flexile' - flexible glass, which didn't break and could be bended by hand. But why did he do so? And could it actually happen? In our answer, we will provide a short guide into the theory of disruptive innovation.



The exact circumstances are known identically from three independent sources, separated by both space and time, likely establishing that the story was a popular and widely circulating one in Ancient Rome. It was first mentioned by Petronius in the famous Satyricon, one of the only two surviving Roman novels.
Just like the title suggests, the book was a satire, primarily targeted at the infamous emperor Nero. The book is full of allegories to bits and pieces of Roman culture which (at least at the time) could be considered mainstream at the time of writing - including the story of Tiberius's glassmaker. (The story is recited along with stories of witches and werewolves, showing that it wasn't believed at the time either.)

Exact story

According to the story, a glassmaker requested an audience from Emperor Tiberius and presented him a glass vial. He asked the emperor to give it back after the demonstration - and then dropped the vial to the ground. Miraculously, it didn't break, but rather dented - according to Petronius, like it was made of bronze.
Yet the emperor's response wasn't applause and a state honour - rather, he executed the glassmaker and destroyed his workshop, fearing that the new invention would undermine the value of gold and silver and collapse the economy.

Three important conclusions can be drawn from the story - one about the emperor, one about the glassmaker and one about the historian who told it.

The emperor's dilemma

Let's propose that the story is true for the purposes of a thought experiment. In that case, Tiberius - the sole decisionmaker in a highly centralised political system - was presented with an unique situation: to decide over the fate of a highly innovative new technology. A material with such properties would have been extremely valuable - and in an age when the only form of money was gold and silver coins, it would have been extremely disruptive. How so?
Tiberius feared the phenomenon called disruptive innovation - this happens when a new invention not only creates a new market for itself, but that market takes over (and destroys) earlier, existing markets for similar technologies. (The most famous example of this would be Harrison Ford's Model T, which at one point composed 50% of total automobiles.).
From a sole ruler's point of view, maintaining stability of all kinds is vital to preserving power - and when existing markets are suddenly endangered, his interests are to protect them over new ones. And when the particular market endangered is that of value storage, the decision to behead the glassmaker becomes even more natural.

The glassmaker's gamble

The second - and possibly most intriguing question - is the glassmaker's. Could he have possibly invented a form of break-resistant, denting glass? Theoretically, yes.
Roman glassmaking - building on centuries-old Hellenistic tradition - reached it's peak during the early Imperial period, around the 1th century AD. The reasons for this are two-fold.
Firstly, the Pax Romana has brought a period of unprecedented growth, stability and prosperity for the Empire, helping artisans engage in interprovincial trade, and in turn face new forms of competition which required the constant improvement of glassmaking techniques.
Secondly, it was during this period that glassblowing was invented - it was quicker, and required less resources per vessel than earlier methods, and generally replaced them - providing an alternate, if smaller example of disruptive innovation.
Other examples of innovation from around the period include colourless glass, window panes and glass mosaics. Actually, Roman glassmaking was so advanced that some of it's achievements couldn't be replicated until the 18th century - hence no wonder that such a story of extraordinary artisanic feat could emerge.

The historian's report

Finally, it's interesting to note the manner and the background of the authors who told about the story. Petronius included it along werewolf fables, Pliny included it in his encyclopedia only to dismiss it as nonsense, and much later Isidore of Seville (a Visigothic bishop in Hispania) did the same. Why?
Basically, the story sounds too good to be true. The earlier glassmaking technologies were invented independently at multiple locations, a trend unlikely to reverse when these glassmaking hubs are constantly competing to stay in business. Even if Tiberius's glassmaker invented such a technology which then was destroyed, it likely would have appeared in other locations sooner or later, out of Tiberius's reach.
The more likely explanation is that the story was an ancient urban legend - which, though less remarkable, signals us that the Roman civilisation was urbanised and advanced enough to cultivate and maintain urban legends, a feat it's medieval successor failed to reproduce.

So what is your input on urband technology legends? Do you have a favourite? Tell us in comments.


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