The first democracies, ancient and modern, were built on slave labour. Like the rest of the ancient world, Athenians bought, sold, and used humans as unpaid workers. In Athens, slaves had some legal rights, but not rights to freedom or equality. The city’s economy and its many wars depended on slave labour; so did ordinary free people in their daily lives. House-slaves kept family secrets and did most of the cleaning, cooking, building, bookkeeping, nursing, tutoring, and countless other tasks. The Scythian police, who were ‘public slaves’ owned and controlled by the demos, patrolled the city in pointed headdresses toting lip-shaped bows. The bodies of slaves strained to build the temples on the Acropolis. Rome’s much larger body of free citizens relied on vast numbers of slaves from across the known world to serve their daily wishes.

Even in ancient times, slavery posed a moral and philosophical problem for slave-owning democracies. Aristotle infamously speaks of ‘natural slaves’ in the first Book of his Politics, identifying slave natures with deficient rationality and self-control. Proponents of early modern colonialism were fond of citing his authority to justify dominion over non-Europeans. Between the late fifteenth and twentieth centuries, a crudely simplified Aristotelianism hooked up with proselytising Christianity and ideas of progress, producing an ideological ménage à trois that helped excuse a global slave trade and white-dominated empires. Masters were Christian, industrious, intelligent, civilised, high up on the evolutionary scale of primates. Slaves and subordinate peoples were infidels, lazy, dim, unenlightened, barbaric, way down on various developmental ladders invented by social and natural scientists.

But decades before Aristotle, ancient writers — especially playwrights — paint a very different picture of slaves as the victims of brute bad luck, many of them greater-souled and far more intelligent than their masters. Throughout the Greek-speaking world, thousands would flock to magnificent outdoor theatres to watch tragedies that depicted great warriors and royalty tumbling from the heights of power into misery and servitude. In non-slave plays, tragic falls usually involved a fatal mistake or character flaw in protagonists or their forebears. In Sophocles’ Antigone, for instance, King Creon loses his children and wife because of his haughty refusal to let the heroine bury her dead brother. In slave plays, though, tragic figures are as blameless as you or your grandmother: characters like Hecuba, the aged widow of Troy’s King Priam, who was enslaved in a war that killed her sons and husband and turned her daughters into the enemy’s concubines.

In the hands of playwrights like Euripides, stories like Hecuba’s don’t just inspire pity. They show enslaved people as equals, in essence, to their masters. What’s more, they issue a warning to slave owners and tyrannical states: never forget that even the weakest, most downtrodden slaves can find ways to hurt you if you drive them to desperation. Hecuba is the very image of vulnerability: old, female, isolated, foreign, traumatised. Yet when her Greek captors sacrifice her daughter and murder her youngest son, she casts off queenly dignity and takes revenge on her son’s killer, Polymestor, slaughtering his sons and gouging out his eyes.

Being a master or a slave, then, was a matter of brute luck. Most ancient slaves were men, women, and children taken captive in wars, or sold by their impecunious families. Some of them already had, or developed, skills far beyond what most freemen and women could boast. Some were poets, or rhapsodes who sang ancestral epics; fine artists and craftsmen who carved statues and painted the plates and wine jugs we admire in museums; doctors; great mathematical brains. Slaves came from upper and lower social ranks in their home countries. Some once wore crowns.

Luck is tychē in Greek, fortuna in Latin. Both words have the feminine gender, and luck was imagined as a moody, changeable goddess who coddles and flatters you until you feel godlike yourself — then dumps you without warning. The message in most ancient stories starring lady luck is that anyone can become a slave; no one is so powerful that they are 100% safe from that wretched fate. War or poverty can strike you down any day and land you in the slave markets of Piraeus, Delos, or Rome. This luck-based account explains slavery without trying to excuse it. In fact, the thinking behind it is quite egalitarian. Instead of saying that slaves and masters are what they are because of natural and/or moral inequalities, it stresses how equal people are — in the most basic ways. We’re all passengers in the same boat tossed about on choppy waters. Any of us can get flung overboard without warning. So don’t get too comfortable playing master to other humans. The wheel keeps turning.

There’s another hard message in the Hecuba story: Masters, beware — slavery might turn a profit, but it’s a high-risk business. Slaves constantly think about escaping, especially if they’re young and fit. Or they gang together and rebel. One way to tell the difference between people and property, said Benjamin Franklin in the course of America’s agonised founding debates, is that ‘sheep will never make any insurrections.’ After Franklin and his fellow slavery-hatersfailed to abolish the practice at the key moment of founding, fears of insurrection grew ever larger. The ancients had a different approach. Quite aware that slaves were no lazier or stupider than they themselves were, free Athenians assigned key public tasks to some of them. There were the Scythian policemen, and slave artisans, priests, archivists, court clerks, civil servants, and public administrators.

Psychologically and ideologically speaking, slavery produced terrible contradictions in both ancient and American democracies. But they were bigger in America, where democracy was born trying to get away with the ultimate contradiction: claiming to be the beacon of universal equality while allowing a roaring slave trade and ‘way of life’ that amounted to barring millions of humans from equal humanity. The convoluted thought patterns that allowed this delusion to stick around for another 80 years didn’t vanish when the Civil War abolished slavery. Masterhood is narcotic: once you’ve had it, it’s hard to go cold turkey. The idea of yourself as someone else’s master gives you a daily high. If poverty or the law rips it away from you, your whole sense of self-worth, your very identity, might disintegrate.

There’s an old debate about whether Aristotle thought that anyone who happened to be a slave possessed a ‘slave nature.’ He does say, however, that the most slavish natures are found in people who can’t control their craving to control others. They dominate others because they can’t master themselves, slaves to their own neediness and anxieties. Today we call these people control freaks, or narcissists. The Greeks just called them tyrants — exactly the sorts of people who look like Fortune’s coddled pets, until the wheel turns.