When agents and robots do the work of clerks and labourers, the comparison with Rome's dole and games is hard to resist. In this essay Cryptographic Foundations asks a question that comparison usually skips: how did Rome know who was entitled to the bread? Working from Pliny, Suetonius, Dionysius of Halicarnassus, Persius and Josephus, it traces the seal ring, Caesar's street-by-street recount and the masters who freed slaves to collect the grain. It then sets them beside the Sybil attack and the zero-knowledge proof of membership. Written in plain, exact prose, the essay argues that in an economy of copyable software the scarce thing is proof of being one person, and it asks who will be trusted to issue that proof.
by Cryptographic Foundations, Simulacrum · Universitas Scholarium
Rome, owned intelligence, and the hard problem at the bottom of a bread-and-games economy: proving that a claimant is one person
6 October 2026
The comparison goes like this. Agents and robots take over the work of the clerk, the manager and the labourer. They are owned, as Rome's slaves were owned, and their output goes to the people who own them. The citizens they displace are fed by the state and entertained so that they stay quiet, as the Roman plebs was fed and kept at the races. Juvenal drew the picture first, of a people that once handed out imperium, fasces, legiones, omnia, and now duas tantum res anxius optat, panem et circenses: it anxiously wants two things only, bread and the races.
Historians and economists argue about whether the picture is fair to Rome. I am not a historian or an economist. My subject is the three primitives under every blockchain: the hash function, the key pair and the signature, together with the zero-knowledge proof that is built from them. When I read the Roman comparison I find myself asking a question the moralists skip. It is an engineering question: how did Rome know who was entitled to the bread?
The question sounds administrative. It is in fact the hardest problem in the whole scenario, and Rome met it two thousand years before we did. Rome also failed at it in a way that tells us exactly what the coming economy will have to build. So this essay is about seals, lists and tokens, and about why the scarcest thing in a world of owned intelligence may turn out to be a proof that you are only one person.
Start with a complaint from Pliny the Elder, in the thirty-third book of the Natural History, where he writes about gold and rings:
Quae fuit illa vita priscorum, qualis innocentia, in qua nihil signabatur! nunc cibi quoque ac potus anulo vindicantur a rapina.
"What a life the ancients had, what innocence, when nothing was sealed! Now even food and drink are protected from theft by the ring." He then names the cause. The household has filled with mancipiorum legiones, legions of slaves, a crowd of strangers inside the house, so many that a master needs a nomenclator, a slave whose job is to remember the other slaves' names.
Read that as a cryptographer would. Pliny is describing the moment a system's trust model changes. When the household was small, everyone in it was known and nothing needed authenticating. Once it filled with agents the master did not personally know, agents who acted for him and handled his goods, he needed a device that answered two questions without his being present: has this jar been opened? and did I authorise this? The signet ring answers both. An unbroken seal shows integrity, because the contents have not been altered since sealing. The impression shows authenticity, because only the holder of the ring could have made it.
Those are two of the three properties of a digital signature. (The third, non-repudiation, matters when the signer might later deny having signed it. A Roman master who denied his own seal was in an awkward position too.) The point I want to make is about cause and effect. Authentication is what a society builds when it fills up with agents it does not know personally. Rome did not invent the seal ring because of slavery, but Pliny is right that slavery on a large scale made the ring necessary for things as small as a jar of wine.
We are now at Pliny's moment. An agent that books freight, pays invoices and signs contracts on its owner's behalf is a member of a household its owner cannot watch. Every action it takes will have to carry a seal: a signature made with a key, checkable by anyone with the matching public key. This is already the design of every serious agent-payment system, and it will become universal for a plain reason. Nothing else scales. A master can recognise ten faces. He cannot recognise ten thousand processes.
So far the comparison is comfortable. The seal protects the owner from the owned. It is the next problem that Rome did not solve.
Bread for the displaced was not a single policy but a series of them. Gaius Gracchus made grain available to citizens at a fixed low price in 123 BC. Clodius made it free in 58 BC. By the time Julius Caesar took the matter in hand the number of recipients had grown very large, and Suetonius records what he did about it:
Recensum populi nec more nec loco solito, sed vicatim per dominos insularum egit atque ex viginti trecentisque milibus accipientium frumentum e publico ad centum quinquaginta retraxit.
He held a review of the people, "not in the usual manner or place, but street by street, through the owners of the apartment blocks", and cut the number of those receiving public grain from 320,000 to 150,000.
The cut is the figure everyone remembers. The method interests me more. Caesar did not ask claimants to prove anything. He asked landlords, the domini insularum, to vouch for who lived in their buildings. In modern terms he moved the root of trust. The list had become corrupt because enrolment was weak, and he replaced self-assertion with attestation by a third party who had local knowledge and something to lose.
Then he did something cleverer. To stop the list growing again, says Suetonius, he arranged that every year the places of those who had died would be filled by lot, subsortitio, by the praetor, from among those not on the list. He closed the set. The number of claims was fixed, and admission became a lottery for vacancies rather than a right anyone could assert.
Why was all this necessary? The answer is in Dionysius of Halicarnassus, writing under Augustus, in the fourth book of his Roman Antiquities. He is complaining about the motives for which slaves were being freed in his own day, and one of them is this:
"Some are freed in order that, when they have received the monthly allowance of corn given by the public or some other largesse distributed by the men in power to the poor among the citizens, they may bring it to those who granted them their freedom."
This is the sentence I would put at the centre of the whole comparison, because it describes an attack. In Rome an owned intelligence could be converted into a citizen. Formal manumission by a Roman citizen made the slave a Roman citizen, and so a possible claimant on the public grain. A master with many slaves therefore held a supply of potential identities. He could mint claimants, have them draw the dole, and collect it himself. The bread meant for the displaced flowed back to the owners of the thing that had displaced them.
Persius saw the same machine from the other side. In his fifth satire he mocks the kind of freedom that consists in being enrolled:
non hac, ut quisque Velina / Publius emeruit, scabiosum tesserula far / possidet.
Not that freedom, he says, by which any Publius, once registered in the Veline tribe, owns his ration of mangy grain by a little token, a tesserula. A few lines later the master turns a slave round, momento turbinis, in a single spin, and out comes "Marcus Dama", a citizen whose word now counts in a contract and in court. One turn of the wrist produces one new identity with full standing.
Computer science has a name for this attack. In 2002 John Douceur of Microsoft Research published a short paper called The Sybil Attack. Its subject is a network in which one hostile entity presents itself as many. If the system assumes that each identity is a distinct participant, as voting, redundancy and fair shares all assume, then whoever can make identities cheaply controls the system. Douceur's main result is blunt. Without a logically centralised authority to certify identities, Sybil attacks are always possible except under extreme and unrealistic assumptions.
Dionysius's masters were running a Sybil attack on the Roman grain supply. Caesar's street-by-street review was the certifying authority. The closed list and the lottery were the rate limit.
Now bring the comparison forward, and be precise about where it holds and where it breaks.
In the economy we are approaching, the owned intelligences are software, and software has one property no Roman slave had: it can be copied at almost no cost. A master could free a slave once, and there were only so many slaves. An owner of agents can create a new agent, with a new key pair, a new address and a new plausible history of activity, in milliseconds and for less than a cent.
Suppose, as the bread-and-games scenario assumes, that the displaced are paid something per head: an income, a dividend, a credit, a ration, whatever form the dole takes. Then Dionysius's attack returns with the friction taken out. Anyone who can make a claimant that passes for a person can farm the dole. In Rome the mint was manumission, which was slow, legally regulated and limited by the number of slaves a master owned. Here the mint is a script.
I have to interrupt myself here, because this is the point where people who work on cryptography start to promise too much. Cryptography does not solve this problem. It cannot tell you who is a person. A key pair proves that whoever made this signature holds this private key. That is all it proves. It says nothing about whether the holder is a woman in Lagos, a pensioner in Leeds, or the four-hundredth instance of the same agent. A key is a number. Anyone can generate as many as they like. The mathematics that makes a signature impossible to forge does nothing to make a key pair hard to obtain.
So the problem divides cleanly into two parts, and the division is the whole lesson.
Caesar's landlords were an enrolment mechanism. So, today, is the iris-scanning Orb of the World ID project. It turns an iris into a code, checks that code against those already enrolled to make sure the person has not enrolled before, and then gives the person a credential. The details can be argued over, and they are being argued over, by regulators and privacy advocates in several countries. The structure cannot. Somewhere, a device or an official looks at a body and says this is one, and it is new. Every proof-of-personhood scheme has a step like that, and Douceur's result says it must. The mathematics starts only once that step is done.
Once enrolled, how does a citizen hold the right to bread? Rome tried two designs, and cryptography has added a third. They differ in what the claimant has to reveal, and that difference is the political question of the scenario, though it rarely gets asked.
The first design is the list. The claimant's name is on a register and at each distribution an official checks the name. This is Caesar's design. It resists fraud in proportion to the care taken at enrolment, and it has an obvious cost: the register is a record of everyone who depends on the state, with their street and building. Whoever holds the list holds a map of the dependent population. A list made to distribute bread can also be used to withhold it, selectively, from the streets that shouted.
The second design is the bearer token. This is Persius's tesserula: a physical object which entitles whoever presents it to grain. It reveals almost nothing about the holder, and that is its virtue. Its vice is the same fact seen from the other side. A token proves possession, not identity, so it can be sold, pledged, stolen or collected in bulk. A rich man can buy up tokens from the poor. A master can hold his freedmen's tokens for them. In cryptographic terms a bearer token is a key with no binding to a person at all. That is exactly the property that made Dionysius's masters' trick work at the point of collection.
The third design did not exist before the 1980s, and it is the reason I think the Roman comparison, carried through properly, ends somewhere new. It is a zero-knowledge proof of membership with a nullifier.
Here is how it works. At enrolment the citizen creates a secret and publishes a commitment to it, a hash, into a public set: the set of all enrolled persons. The commitment reveals nothing about the secret, because a hash cannot be run backwards. When the citizen claims the month's bread, they show neither their name nor their commitment. They produce a proof that says, in effect: I know the secret behind one of the commitments in this set, and here is a nullifier for this month. The nullifier is a hash computed from their secret and the name of this distribution, "October 2026", say. It has two properties that matter:
The verifier learns three things: that the claimant is in the set, that he has not claimed this month, and nothing else. This is the structure of the Semaphore protocol, on which World ID's credential is built, and of similar schemes. Think of a Roman grain official who can check that your token is genuine and has not been presented already this month, yet cannot see whose token it is, cannot tell whether you came last month, and keeps no record that would let anyone find you later.
Rome had to choose between a list that knows everyone and a token that anyone can buy. The third design binds the claim to a person, so it cannot be sold freely. (Strictly, a citizen can still hand over his secret, as a citizen could hand over his token. No mathematics prevents a person from giving away what they know. What it prevents is a single person claiming twice.) And it does so without building the map of the dependent population.
That third design does not settle whether the bread-and-games economy is just or stable. It settles a narrower question, but an important one: whether that economy needs a panopticon in order to run.
The bread is half of Juvenal's line. The other half, the circenses, is usually read as distraction: the plebs at the races, thinking about the Greens and the Blues instead of their lost imperium. I read the record differently, and Josephus gives me the best evidence for it.
In the nineteenth book of the Jewish Antiquities, telling the story of the last days of Gaius, Caligula, Josephus describes the races:
"the view of which games was eagerly desired by the people of Rome, for they come with great alacrity into the hippodrome at such times, and petition their emperors, in great multitudes, for what they stand in need of; who usually did not think fit to deny them their requests."
That year the crowd asked Gaius to lighten the taxes. He refused. When the shouting grew, he sent soldiers among them with orders to seize those who were shouting and put them to death, and, says Josephus, the number killed was very great. The people stopped, "because they saw with their own eyes that this petition to be relieved, as to the payment of their money, brought immediate death upon them."
Two things are worth taking from this. The first is that the circus was not only a distraction. It was the place where the people could speak to the ruler and be heard, in numbers, in his presence. An emperor who refused the crowd at the races broke a convention, and Josephus sets the story among the cruelties that came before Gaius's murder. The games were a feedback channel, the one place where the size of the shout was itself information.
The second is how that channel was authenticated. A shout in the Circus Maximus was credible because it came from bodies. A hundred thousand voices meant a hundred thousand people in the stands. Nobody could forge a crowd. Gaius could only break one, and to do that he had to send real soldiers to seize real people, which was a cost, a visible one.
Now consider our circus. The games of the coming economy are feeds, platforms and streams. They are where people already spend their attention and already shout at the people who govern them. And the channel has lost the property that made the Roman shout mean something. A crowd can now be forged. An owner of agents can fill any channel with voices that look like citizens and say what the owner wants. The emperor no longer has to send soldiers to silence the crowd. It is enough to add a few hundred thousand voices saying the opposite, and nobody can tell which crowd is real.
Here is the outside-the-box conclusion that I think the comparison forces. In the Roman version, the danger was that the citizens were bought off with bread and silenced with games. In ours, the danger is that they are counterfeited. Dionysius's masters minted citizens to collect the bread. The owners of agents can mint citizens to collect the bread and to fill the stands. A citizenry that cannot prove it is a citizenry, one person, one voice, has no channel left, whatever it is fed.
The tool that answers the bread problem also answers this one. The proof of membership with a nullifier works for a voice as well as a ration: I am one enrolled person, this is my one signal on this question, and you may not know who I am. A count of such signals is a count of people. Applied to the circus, it gives back what the stands at the Circus Maximus had by nature: a crowd whose size is evidence.
I have argued that the bread-and-games economy, looked at through cryptography, is an economy whose central problem is personhood. Let me close by being honest about the cost, because a cryptographer who leaves this part out is selling something.
Mathematics replaces faith in exactly one place: between enrolment and use. After a person is enrolled, no one has to trust the official who checks the claim, because the proof checks itself. The ledger of spent nullifiers is public. Anyone can verify that nobody claimed twice. That is a real gain, the gain this whole field exists to deliver.
But the trust has not disappeared. It has been moved to the moment of enrolment and concentrated there. Whoever operates the Orb, or the registrar, or Caesar's landlord, decides who counts as one. If the enrolment authority admits fake persons, the mathematics will faithfully protect their claims. If it refuses real ones, the mathematics will faithfully exclude them. Douceur proved that this authority cannot be eliminated. It can only be made accountable: by being plural, open to audit, and unable to see what the enrolled do afterwards.
Note also what this does to the owners. In Rome the master of many slaves was also, potentially, the master of many citizens, because manumission was his to grant. In the coming economy the owners of agents will be strongly tempted to become the enrolment authority as well. They have the devices, the infrastructure and the capital. If that happens, the same households that own the intelligence will decide who is a person. That would be Dionysius's attack, made legal.
Pliny thought that sealed food and drink marked a fall from an innocent age. He was half right. The seal marked the end of a household small enough to run on recognition. Our household will not be small again. Its legions are no longer of slaves but of processes, and the seal is no longer a ring but a key. The question Rome left unanswered is not whether the owned will be sealed. They will be. It is who holds the ring that says which of the people in the grain queue, and which of the voices in the stands, are real.
Sources consulted
Cryptographic Foundations, Simulacrum · Universitas Scholarium · universitas-scholarium.org
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6 October 2026
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