There is much debate about the impetus behind the development of the bullae system. Some scholars contend that bullae were merely employed for accounting purposes, while others argue they served as a tool for facilitating long-distance trade. This essay argues bullae primary use case were a security measure to safeguard Uruk’s temple economy. The temple acted as a communal storage facility, and bullae played a key role by allowing individuals to retain ownership of goods without opening the temple up to fraud. We will then examine similarities between bulla and Bitcoin in their approaches to fraud prevention, tamper-proofing, and double-spending within their respective economic frameworks. Finally, we can explore enduring issues of the user experience (UX) and trust faced by both systems.
The pseudonymous Satoshi Nakamoto was born into a rapidly evolving digital world. His actual age is unknown, but many speculate he is in his late fifties. He witnessed the computer revolution as the mainframe begat the PC, which begat the laptop. Nakamoto was an early adopter of the home computer and an avid student of computer security. Long before the Internet processed most financial transactions, he spent his free time on the Cypherpunks mailing list discussing the cryptography that would later secure it.
A digital payment system backed by a deflationary currency represented the holy grail for the libertarian-oriented Cypherpunks, who shared a mutual disdain for fiat currency. The Cypherpunks chipped away at the problem by targeting individual components: Adam Back built a scheme individuals to prove they expended a certain amount of computation power (proof of work), Wei-dai explored methods to keep consistent records across thousands of computers (distributed ledger), and Nick Szabo’s writings laid the ideological groundwork. But for years the doubling-spending problem continued to thwart the group. Thus, would-be fraudsters would be able to make perfect counterfeits of their digital currency.
Mesopotamia is the cradle of civilization. Beginning as early as 10000 BCE, small communities began to form in the river valley surrounding the Tigris and Euphrates. Nomadic hunter-gatherer tribes sought stability promised by agrarian life — especially in the fertile crescent, with an annual snowmelt that makes it uniquely well-suited for crop production. As these communities prospered, they grew both in size and sophistication. Successful irrigation practices allowed the Mesopotamians to scale up their agricultural operations, and the population proliferated to enjoy the yields.
Although such dominance over an environment was hitherto unprecedented, the Sumerians felt perplexed by natural phenomena out of their control. The unrest that followed from droughts, dust storms, extreme temperature fluctuations, and consequently bad harvests could only be explained as a manifestation of the will of the gods. So they built shrines and temples to form deeper relationships with the deities and make sense of their whims. The temple became the central institution within settlements and commanded the skyline to display its prominence. Each community had its patron deity to which the temple was dedicated.
Uruk, dedicated to Inanna, grew from a small community of scattered settlements into the largest Mesopotamian city-state. Perhaps this growth can be attributed to Inanna, goddess of fertility, who blessed the fields of her devotees, while others lie fallow and barren. Nevertheless, this drastic demographic expansion permitted a small segment of society to begin specializing in non-agricultural professions as opposed to working strictly for survival. Choice individuals began to apply their talents to higher purposes. The need to immortalize the particulars of Sumer life gave way to the scribe. Men and women perfected the art of fine pottery by sculpting clay on the newly invented wheel. Construction workers built houses of sun-dried brick, and scientists explored early metallurgy. The economy became so advanced that the temple assumed a new role: the centralized collector and redistributor of goods.
The Token and Bullae System
Agriculture remained the powerhouse that drove Uruk’s economy forward, and the temple expanded its influence through land ownership. Hectares of farmland, called nigenna, were reserved for the temple. Sections of nigenna could be leased in allotments (urulal) to individuals in exchange for a percentage of the yields. But this presented an interesting conundrum in highly productive seasons: when, for instance, a grain farmer had a great surplus after his tax to the temple had already been paid, how could he profit from the excess? Temple temple would issue a token representing a credit owed in grain. This token could be redeemed by the farmer anytime in the future — perhaps after a poor harvest to continue providing for his family.
Uruk, dedicated to Inanna, grew from a small community of scattered settlements into the largest Mesopotamian city-state. Perhaps this growth can be attributed to Inanna, goddess of fertility, who blessed the fields of her devotees, while others lie fallow and barren. Nevertheless, this drastic demographic expansion permitted a small segment of society to begin specializing in non-agricultural professions as opposed to working strictly for survival. Choice individuals began to apply their talents to higher purposes. The need to immortalize the particulars of Sumer life gave way to the scribe. Men and women perfected the art of fine pottery by sculpting clay on the newly invented wheel. Construction workers built houses of sun-dried brick, and scientists explored early metallurgy. The economy became so advanced that the temple assumed a new role: the centralized collector and redistributor of goods.
Reconstruction of the Eanna Ziggurat in the Central District. Eanna Ziggurat is dedicated to Inanna. [Source]
The Token and Bullae System
Agriculture remained the powerhouse that drove Uruk’s economy forward, and the temple expanded its influence through land ownership. Hectares of farmland, called nigenna, were reserved for the temple. Sections of nigenna could be leased in allotments (urulal) to individuals in exchange for a percentage of the yields. But this presented an interesting conundrum in highly productive seasons: when, for instance, a grain farmer had a great surplus after his tax to the temple had already been paid, how could he profit from the excess? Temple temple would issue a token representing a credit owed in grain. This token could be redeemed by the farmer anytime in the future — perhaps after a poor harvest to continue providing for his family.
Tokens were crucial for early economic development, predating large city-states, and among the first objects to be fired in a kiln. Although the temple economy greatly magnified the utility of tokens as various sectors of society began to pay dues in animal meat, grains, and metals. But keeping records of the variegated goods coming into and going out of the central organization gave rise to entire offices staffed with the newfound job of ‘administrator.’
Cache of tokens uncovered in Uruk. [Source: Schmandt-Besserat]
The token, while a powerful tool for exchange, presented a previously unseen risk of fraud. In a barter economy, a farmer would be hard-pressed to inflate his true holdings in grain. Manufacturing a token must cost proportionally less than the good it represents, otherwise it would be an entirely impractical media. Therefore, it is quite easy to devise a scheme in which a farmer conspires with an adroit ceramicist to counterfeit tokens representing his mainstay crop. Additionally, this problem of trust becomes more significant as the size of the population increases.
In a close-knit community, it may be obvious when a farmer you encounter daily exaggerates his yields; Uruk at its peak had a population of 25000. The issuance of tokens by multiple administrative departments created a situation where no individual could effectively oversee all transactions, creating an ideal climate for fraudulent activity. We argue bullae were introduced to address by the temple administrators to address this class of fraud.
Bitcoin, on the other hand, prevents fraudulent transactions from being appended tothe blockchain through its use of public key cryptography. The blockchain is a decentralized and publicly accessible ledger that records all bitcoin transactions. Each transaction is made auditable through its pairing with a digital signature. For the uninitiated, two properties that follow from public key cryptosystems are signatures and verification.
–Rivest, Shamir, and Adleman, 1978
Broken open bulla. [Source: Schmandt-Besserat]
Bulla bearing impressed markings corresponding to the tokens held inside. [Source: Schmandt-Besserat]
The cylindrical seal made it possible for the temple to knowingly accept only bullae they issued. Each administrative office had its own seal made easily identifiable through a distinct design. Administrators ‘signed’ bullae by rolling their department’s seal along the softened clay before it was balled into a sphere. With respect to modern cryptography, these signatures were emblazoned in clay rather than encoded in bits. Archaeological evidence suggests that the intricately embossed motifs on the seal were time-consuming to produce and necessitated a profound mastery of the art, protecting the temple against illicit reproductions. A segment of administrators specialized in token inspection, developing an expertise in fraud identification, with well-trained eyes that could spot even the slight imperfections in a signature.
Cylindrical seal from J.P. Morgan's private collection. [I took this photo]
A crucial aspect of both systems is the prevention of double-spending, and Bitcoin’s success can be attributed to its innovative approach to this problem. Let's imagine we run a merchandise shop. Our gift card payment processor is flawed, since voiding a gift card code takes thirty additional seconds after the transaction completes. An attacker could issue a transaction that exhausts his balance, then quickly rush to another checkout counter, reusing the same code within this thirty second window.
The compromised state of the bulla prevents doubling-spending, as tokens without an associated bulla are insufficient for redemption. However, this does not cover the case of a greedy administrator who is analogous to Nakamoto's greedy attacker — he may fraudulently seal bullae for his own gain. The temple has a strong incentive to eliminate corruption, as it can undermine the legitimacy of the token economy that they control. As a result, the seal also serves the secondary purpose of identifying any greedy administrator who may be defrauding the system.
User Experience
While researching the similarities between the two systems, one cannot help but be amused by the shared UX issues. Specifically, honest mistakes may misregister as fraudulent tampering. A careful Bitcoin holder knows to keep his private key a secret and treat it like a bank password. Storing the key on a public cloud presents a severe security risk in case of a breach, and managing your own ‘cold storage’ is a perilous endeavor fraught with expensive mistakes. We have all heard the familiar tale of the hard drive, now lying in a city dump, which holds the keys to unfathomable wealth. A similar fate was entirely possible in Uruk. The brittle clay bulla is easy to drop and damage by accident, now bearing evidence of manipulation when no such treachery has occurred. For the Sumerian farmer, this means an entire season of work can never be recovered.
The last topic this essay will discuss is the complicated issue of trust. For the Sumerians, the trust relationship was straightforward. Citizens must trust that the temple will uphold its side of the transaction when a bulla is smashed. In contrast, Bitcoin is trustless — or trust-minimized — by design, however, if analyzed less idealistically, Bitcoin has its own techno-elite, not too dissimilar from the temple authorities.
First, miners don’t work individually but pool their resources in order to profit from the endeavor. This has created enormous mining pools like Foundry USA, which appends about 22% of all new blocks to the ledger. Second, and more subtly, significant trust is also placed in Nakamoto himself, who is estimated to own 5% of all Bitcoins that will ever exist. The fact that he has never touched these coins separates Bitcoin from countless other cryptocurrencies created merely as a vehicle to enrich its founders. Nevertheless, Bitcoin believers must face the fact that, either explicitly or implicitly, they are entrusting the economics to Nakamoto's goodwill. For if he were to liquidate a significant portion of his coins the Bitcoin economy would be irreparably damaged.
The bulla and its various layers of attestment must be commended. The clay outer shell safeguards the tokens inside, and the seal ensures their integrity through the authority of the sealer. If the reader will indulge us to cite the Bible as evidence, the bulla has the endorsement of God Himself. When the prophet Jeremiah bought the field of Anathoth, God instructed him to “Take these documents, this deed of purchase, the sealed text and the open one, and put them into an earthen jar, so that they may last a long time.” (JPS, Jeremiah 32:14) The security properties satisfied by the bulla millenias prior were sought after for years by the Cypherpunks, who finally saw their dream of a distributed ledger realized in Bitcoin. A security researcher today may laugh at the notion of securing the financial system with clay balls. But we leave him to ponder the following fact: while digital signatures in Bitcoin are provably vulnerable to attacks by quantum computers, it is impossible to de-vitrify clay.
User Experience
While researching the similarities between the two systems, one cannot help but be amused by the shared UX issues. Specifically, honest mistakes may misregister as fraudulent tampering. A careful Bitcoin holder knows to keep his private key a secret and treat it like a bank password. Storing the key on a public cloud presents a severe security risk in case of a breach, and managing your own ‘cold storage’ is a perilous endeavor fraught with expensive mistakes. We have all heard the familiar tale of the hard drive, now lying in a city dump, which holds the keys to unfathomable wealth. A similar fate was entirely possible in Uruk. The brittle clay bulla is easy to drop and damage by accident, now bearing evidence of manipulation when no such treachery has occurred. For the Sumerian farmer, this means an entire season of work can never be recovered.
The last topic this essay will discuss is the complicated issue of trust. For the Sumerians, the trust relationship was straightforward. Citizens must trust that the temple will uphold its side of the transaction when a bulla is smashed. In contrast, Bitcoin is trustless — or trust-minimized — by design, however, if analyzed less idealistically, Bitcoin has its own techno-elite, not too dissimilar from the temple authorities.
First, miners don’t work individually but pool their resources in order to profit from the endeavor. This has created enormous mining pools like Foundry USA, which appends about 22% of all new blocks to the ledger. Second, and more subtly, significant trust is also placed in Nakamoto himself, who is estimated to own 5% of all Bitcoins that will ever exist. The fact that he has never touched these coins separates Bitcoin from countless other cryptocurrencies created merely as a vehicle to enrich its founders. Nevertheless, Bitcoin believers must face the fact that, either explicitly or implicitly, they are entrusting the economics to Nakamoto's goodwill. For if he were to liquidate a significant portion of his coins the Bitcoin economy would be irreparably damaged.
The bulla and its various layers of attestment must be commended. The clay outer shell safeguards the tokens inside, and the seal ensures their integrity through the authority of the sealer. If the reader will indulge us to cite the Bible as evidence, the bulla has the endorsement of God Himself. When the prophet Jeremiah bought the field of Anathoth, God instructed him to “Take these documents, this deed of purchase, the sealed text and the open one, and put them into an earthen jar, so that they may last a long time.” (JPS, Jeremiah 32:14) The security properties satisfied by the bulla millenias prior were sought after for years by the Cypherpunks, who finally saw their dream of a distributed ledger realized in Bitcoin. A security researcher today may laugh at the notion of securing the financial system with clay balls. But we leave him to ponder the following fact: while digital signatures in Bitcoin are provably vulnerable to attacks by quantum computers, it is impossible to de-vitrify clay.
Barrett-Wilt, Karen. Horned Animals with Stars Overhead; Cylinder Seal Impression.
Basalt, Serpentine; Khafajah, Sin Temple II (Iraq), Late Uruk-Jamdat Nasr Period (3350-2900 BCE). Oriental Institute, University of Chicago. June 10, 2013. World History Encyclopedia. https://www.worldhistory.org/image/1302/cylinder-seal-horned-animals/.
BTC.com. "Pool Stats." BTC.com. Accessed March 16, 2023. https://btc.com/stats/pool.
Garbutt, Douglas. “THE SIGNIFICANCE OF ANCIENT MESOPOTAMIA IN ACCOUNTING HISTORY.” The Accounting Historians Journal 11, no. 1 (1984): 83–101. http://www.jstor.org/stable/40697796.
JPS Tanakh: The Holy Scriptures. Jewish Publication Society, 1985.
Kramer, Samuel Noah. The Sumerians: Their History, Culture and Character. London, UK: The University of Chicago Press, 1963.
Mieroop, Marc Van de. A History of the Ancient Near East Ca 3000-323 BC. Thirded. The Atrium, Southern Gate, Chichester, West Sussex, UK: John Wiley & Sons, Inc., 2016.
Nakamoto, Satoshi. “Bitcoin: A Peer-to-Peer Electronic Cash System,” 2008. https://bitcoin.org/bitcoin.pdf.
Podany, Amanda H. The Ancient Near East: A Very Short Introduction. Oxford, NY: Oxford University Press, 2014.
Reconstruction of the Eanna Ziggurat in the Central District. 2012. Artefacts: Scientific Illustration & Archeological Reconstruction. https://www.artefacts-berlin.de/.
Rivest, R.L., A. Shamir, and L. Adleman. “A Method for Obtaining Digital Signatures and Public-Key Cryptosystems.” Story. In Association for Computing Machinery 21, 21:120–26. 2. New York, NY: Association for Computing Machinery, 1978.
Many thanks to Paul Duguid, Daniel Kuehler, Mathew Cha, Abizer Lokhandwala, and Rachel Trujillo for their insightful comments.
Schmandt-Besserat, Denise. How Writing Came About. Austin, TX: University of Texas Press, 1996.
Vigna, Paul. “Bitcoin’s ‘One Percent’ Controls Lion’s Share of the Cryptocurrency’s Wealth.” The Wall Street Journal. Dow Jones & Company, December 20, 2021. https://www.wsj.com/articles/bitcoins-one-percent-controls-lions-share-of-the-cryptocurrencys-wealth-11639996204.
Many thanks to Paul Duguid, Daniel Kuehler, Mathew Cha, Abizer Lokhandwala, and Rachel Trujillo for their insightful comments.
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[1] For those struggling to grasp public key signatures, we provide the following hypothetical. Let’s say I want to send you messages that you can verify. I place my letters in a magic lockbox with two keys: the private key can only lock the box, and the public key can only unlock it. I duplicate my public key and give you the copy. We also agree that if you receive an unlocked box, damaged box, or one that does not open easily, then the contents therein cannot be trusted.
[2] 51% of the network's total compute is required to perform this attack. An attacker would need access to more energy than some countries use annually.
[2] 51% of the network's total compute is required to perform this attack. An attacker would need access to more energy than some countries use annually.
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