Traditionally, Memorial Day weekend marks the start of summer, with beach and lake trips, barbecues and pools opening. In 2020, however, many Americans will spend the long weekend being tired of quarantining and looking for any sign that it is safe to return to normal. Yet, even as most governors start to open up states to varying degrees, many city officials are reminding everyone that in places from Chicago to Gallup, N.M., the infection and death toll are increasing and therefore stay at home orders need to continue.

When will it be safe to emerge from shutdowns, and what will our new normal look like?

These are questions that have circulated across historical ages.

The deadliest pandemic ever to strike the ancient world made it to the capital of the eastern Roman Empire, Byzantium (now Istanbul) in 542 A.D. It certainly killed tens of millions of people, and probably many more. The epidemiological track of this plague, the responses of Emperor Justinian, and, above all, the success of the population of Byzantium in “flattening the curve” by spontaneously self-isolating offer provocative parallels to the current situation as we argue over how to emerge from widespread shutdowns to create our new normal.

In thinking about what that normal might need to be, we should in particular remember the edge that the people of Byzantium gave themselves in combating the infection by staying home even when there were no government restrictions on their movements.

The plague traveled westward from eastern Asia along the international trade route that connected east to west via the Indian Ocean and the Red Sea to ports in the Mediterranean. Countless merchants and workers were constantly involved in close contact with one another and their customers as they imported the pepper, spices and silk that the Roman world craved. Ships at sea became nests of infection, which then traveled inland when the goods were offloaded for delivery.

From the eastern Mediterranean, the disease then migrated across North Africa and into Europe. A form of bubonic plague (Y. pestis), it infected human beings not only through the bites of fleas who had sucked the blood of infected rats, but also likely through aerosol transmission from person to person. Cities were the first to be affected because of their population density, but the devastation eventually extended to rural populations as well. Seasonal weather changes brought no relief. Climate change — cooler temperatures caused by dust in the atmosphere from massive volcanic eruptions — seems to have allowed the bacteria to thrive even during summer months.

Several contemporary eyewitnesses recorded the unpredictable fate of those who became infected. Many people didn’t even initially realize that they were ill; they experienced a mild elevation in their temperature, but their skin wasn’t flushed and they didn’t otherwise feel sick. Doctors told these people without symptoms not to be worried — and then a day or two later they became violently ill. Painful, tumor-like swellings — buboes — erupted on their bodies, especially in their groins. Some even suddenly collapsed or became comatose, while others vomited blood or became delirious; still others turned randomly aggressive.

The illness was so disorienting that some people saw demons that they believed were infecting them or dreamed that monsters told them they were going to die. Health-care workers became exhausted. No universal treatment could be found; what seemingly helped one patient would destroy the next. Some died without lingering, while others suffered for days. Some who recovered then contracted the disease a second time. Total uncertainty continued to prevail about everyone’s fate as the plague made its way through the world.

In the metropolis of Byzantium, the death rate reached 10,000 or more dying every day. Contemporaries estimated half of the capital city’s half-million inhabitants died. The number of corpses overwhelmed families’ ability to bury their dead — or even dispose of the bodies. The stench of decomposition that filled the air drove the living to despair.

With traders, workers and customers increasingly fearful of their usual interactions, the economy soon began to crater. The entire city then came to a standstill as if it had perished, and so its food supply dwindled. This in turn led to essential supplies vanishing from the city’s markets.

Emperor Justinian failed to lead the people through the crisis. When the streets became choked with putrefying corpses, he at last sent in the army to clear the thoroughfares by dragging the rotting remains into mass graves or stuffing them into the towers of the city’s fortification walls.

Justinian allowed price gouging to devastate the supply chain and empty people’s pockets. Lenders pressured him to enforce payments of mortgage loans and other contracts. The economic situation became so bad he finally had to remit arrears of tax payments, but then as government revenue dwindled, he demanded still higher taxes be paid. Society reeled from this failure of leadership.

But the people responded, spontaneously adopting what we are now calling “social distancing.” The normally packed streets of the capital city were practically deserted because everyone who could was staying indoors at home. Workers of all kinds stopped going to their jobs, and government officials ceased attending the imperial court or occupying their offices. The only people seen outside were those who had to carry off a body for disposal.

When they were obliged to go out, people wrote this message on a tablet that they hung from an arm: “I am so-and-so, child of family so-and-so, from such-and-such a neighborhood. If I die, for God’s sake, and to show his mercy and goodness, let them know at my house, and let my people come to bury me.”

The result of the population’s voluntary self-quarantine was remarkable: the crest of the infection had lasted about three months, but now it took only about another month for the virulence of the disease to fade to a level that allowed society to begin to revive.

This outcome seems especially worth noting because this plague kept coming back again and again at unpredictable intervals. In the 590s, for example, the pope in Rome, Gregory the Great, lamented the loss of an enormous number of the region’s population: “almost no one remains who can do any work or provide any service.” As the historian Kyle Harper sums up the history of this plague, “it was a chain explosion that sounded for two centuries.”

We can hope our modern world escapes this terrible fate, but the success of the people of Byzantium in devising their own lockdown should encourage us to take the initiative in acting together to protect ourselves and our society.