When a new coronavirus emerged in China and began spreading around the world, including in the United States, President Donald Trump’s many critics in the American foreign-policy establishment were quick to identify him as part of the problem. Trump had campaigned on an “America first” foreign policy, which after his victory was enshrined in the official National Security Strategy that his administration published in 2017. At the time, I served in the administration and orchestrated the writing of that document. In the years since, Trump has been criticized for supposedly overturning the post–World War II order and rejecting the role the United States has long played in the world. Amid a global pandemic, he’s being accused—on this site and elsewhere—of alienating allies, undercutting multinational cooperation, and causing America to fight the coronavirus alone.

In a large windowless room in the bowels of the CIA, there is a sign that reads Every day is September 12th. When I first saw those words, during a tour of the agency’s operations, I felt conflicted. As a New Yorker who witnessed the 9/11 attacks, I once felt that way myself, but by the time I saw the sign, during the second term of the Obama administration, it seemed to ignore all the things that our country had gotten wrong because of that mindset. Now, as COVID-19 has transformed the way that Americans live, and threatens to claim exponentially more lives than any terrorist has, it is time to finally end the chapter of our history that began on September 11, 2001.

I say that as someone whose life was shaped by 9/11. I was a 24-year-old graduate student working on a city-council campaign when I watched the second plane curve into the World Trade Center and then saw the first tower collapse. Everything that I’d done in my life up to that point suddenly seemed trivial. I walked several miles to my apartment, as my fellow New Yorkers came out into the streets to be near one another (as we can’t be today). In the days that followed, my Queens neighborhood was the setting for a number of funerals for firemen. I will never forget the image of one devastated widow sitting in a lawn chair in her front yard, receiving condolences from a line of the toughest—but most broken—men I had ever seen.

Three months ago, no one knew that SARS-CoV-2 existed. Now the virus has spread to almost every country, infecting at least 446,000 people whom we know about, and many more whom we do not. It has crashed economies and broken health-care systems, filled hospitals and emptied public spaces. It has separated people from their workplaces and their friends. It has disrupted modern society on a scale that most living people have never witnessed. Soon, most everyone in the United States will know someone who has been infected. Like World War II or the 9/11 attacks, this pandemic has already imprinted itself upon the nation’s psyche.

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A global pandemic of this scale was inevitable. In recent years, hundreds of health experts have written books, white papers, and op-eds warning of the possibility. Bill Gates has been telling anyone who would listen, including the 18 million viewers of his TED Talk. In 2018, I wrote a story for The Atlantic arguing that America was not ready for the pandemic that would eventually come. In October, the Johns Hopkins Center for Health Security war-gamed what might happen if a new coronavirus swept the globe. And then one did. Hypotheticals became reality. “What if?” became “Now what?”

From inside her living room in London, Paula Koelemeijer can feel the world around her growing quieter.

Koelemeijer, a seismologist, has a miniature seismometer sitting on a concrete slab at the base of her first-floor fireplace. The apparatus, though smaller than a box of tissues, can sense all kinds of movement, from the rattle of trains on the tracks near Koelemeijer’s home to the waves of earthquakes rolling in from afar. Since the United Kingdom announced stricter social-distancing rules last month, telling residents not to leave their home except for essential reasons, the seismometer has registered a sharp decrease in the vibrations produced by human activity.

With fewer trains, buses, and people pounding the pavement, the usual hum of public life has vanished, and so has its dependable rhythms: Before the spread of COVID-19 shut down the city, Koelemeijer could plot the seismometer’s data and see the train schedule reflected in the spikes, down to the minute. Now, with fewer trains running, the spikes seem to come at random.

Bill de Blasio has long been spoiling for a fight, just not the one now before him and his city. When he became the 109th mayor of New York, on a colorless winter day in 2014, he promised to lead a struggle against “injustice and inequality.” Although he has had some genuine successes, he has failed to turn the city into a Copenhagen-on-the-Hudson. He hasn’t turned it into Caracas, either. New York is pretty much the same global metropolis it was when he took over.

Aware that his progressive ambitions have been frustrated, de Blasio has complained that legions of enemies—conservatives, capitalists, newspaper headline writers—are arrayed against his vision for the city.

However determined these forces have been to undo him, they are not responsible for what New York magazine called, on March 26, “his worst week as mayor.” Worse than the week in 2014 when two police officers were shot and killed, degrading his relationship with the department. Worse than the many weeks in 2016 of overlapping ethics investigations, which threatened to ensnare the mayor and his top aides.

Updated at 7:22 p.m. ET on April 4, 2020.

As the coronavirus pandemic continues, many people are now overthinking things they never used to think about at all. Can you go outside? What if you’re walking downwind of another person? What if you’re stuck waiting at a crosswalk and someone is there? What if you’re going for a run, and another runner is heading toward you, and the sidewalk is narrow? Suddenly, daily mundanities seem to demand strategy.

Much of this confusion stems from the shifting conversation around the pandemic. Thus far, the official line has been that the new coronavirus, SARS-CoV-2, could be transmitted only through close contact with infected people or contaminated surfaces. But recently, news reports have suggested that the coronavirus can spread through the air. After 60 choir members in Washington State rehearsed together, 45 fell sick, even though no one seemed symptomatic at the time. Now people who were already feeling cooped up are worrying about going outside. Many state guidelines are ambiguous, and medical advice can muddy matters further. When the writer Deborah Copaken came down with COVID-19 symptoms, her doctor chided her for riding her bike through New York City a week earlier. Going outside in the city wasn’t safe, the physician implied, with “viral load everywhere.”

Fear sweeps the land. Many businesses collapse. Some huge fortunes are made. Panicked consumers stockpile paper, food, and weapons. The government’s reaction is inconsistent and ineffectual. Ordinary commerce grinds to a halt; investors can find no safe assets. Political factionalism grows more intense. Everything falls apart.

This was all as true of revolutionary France in 1789 and 1790 as it is of the United States today. Are we at the beginning of a revolution that has yet to be named? Do we want to be? That we are on the verge of a major transformation seems obvious. The onset of the next Depression, a challenge akin to World War II, a national midlife crisis—these comparisons have been offered and many more. But few are calling our current moment a revolution, and some have suggested that the coronavirus pandemic—coinciding as it has with the surge in Joe Biden’s bid for the Democratic presidential nomination and the decline of Bernie Sanders’s—marks the end of any such possibility. “The Coronavirus Killed the Revolution,” declared the headline of a recent essay in The Atlantic by Shadi Hamid, who argued that the COVID-19 crisis makes people crave “normalcy” over deep structural change. As a historian of 18th- and 19th-century France, I think claims like these are mistaken.

My childhood was, by most definitions, pretty strange. I grew up a Russian Jewish immigrant in Midland, Texas, in a region whose biggest claims to fame are being the onetime home of George W. Bush and the inspiration for Friday Night Lights. In preschool, I got in trouble for not praying before eating my snack; later, I didn’t know what this “Super Bowl” everyone kept talking about was. I felt hopelessly different from everyone else in our town.

Even after we moved to a Dallas suburb, I never encountered another Russian immigrant kid like me. I rode the bus alone. I spent almost every evening alone. I began talking to myself—a habit that has unfortunately stuck. Once, someone toilet-papered our house, and I had to explain to my parents that this is what American kids do to losers. Undeterred, my dad eagerly raked the toilet paper into a garbage bag and put it in my parents’ bathroom for future use. “Free toilet paper!” he said happily over dinner.

Perhaps a testament to how close Britain has come to losing its way is the fact that it took a pandemic, an emergency of foggy complexity, for the country to get back on its path. This was a weekend that felt defining, not just for the immediate story, the coronavirus, but for British politics—and for Britain itself.

It was not a good weekend. Prime Minister Boris Johnson was hospitalized, and Britain’s death toll jumped as another 621 people died over 24 hours. The gravity of the situation moved the Queen to deliver an emergency address to the nation, something she has done only a handful of times in her 68-year reign. This was not a weekend in which Britain reached, or even caught a glimpse of, the peak of the coronavirus outbreak—never mind found a route back down from it and off the mountain.

In a matter of weeks, the coronavirus has gone from a novel, distant threat to an enemy besieging cities and towns across the world. The burden of COVID-19 and the economic upheaval wrought by the measures to contain it feel epochal. Humanity now has a common foe, and we will grow increasingly familiar with its face.

Yet plenty of this virus’s aspects remain unknown. The developing wisdom—earned the hard way in Wuhan, Washington, and Italy—has been that older people and sicker people are substantially more likely to suffer severe illness or die from COVID-19 than their younger, healthier counterparts. Older people are much more likely than young people to have lung disease, kidney disease, hypertension, or heart disease, and those conditions are more likely to transform a coronavirus infection into something nastier. But what happens when these assumptions don’t hold up, and the young people battling the pandemic share the same risks?