Mercifully for us, what happened in Nice, France, on Bastille Day didn't happen on the National Mall during the annual Fourth of July concert or at Sailfest last weekend.

We all worry, with good reason, that it could. We're relieved when an event ends the way it was supposed to, with fireworks as the only explosions, and no shots fired.

That's terrorism at work, rippling outward to everyone beyond the scene of the massacre and gradually stripping away any comforting rationalizations about why it would not happen here.

We have been educated by this grisly curriculum: It could happen anywhere, even though it won't happen everywhere.

As the nation that experienced the most overwhelming of concerted terrorist acts on Sept. 11, 2001, the United States has countered with vastly more sophisticated security and communications among law enforcement and the military, which is another way of saying we have lost our innocence. No more strolling unhindered into the state Capitol the way citizens used to do to talk to their representatives. No more showing up 10 minutes before the flight boards. K9s and armed officers in railroad stations. And yet we know these measures only help, they do not insure.

Terrorism strikes fear because it is so impersonal. A terrorist who wants to kill Americans or tourists or Christians or any other category of humans doesn't care what individuals he targets. It is not a case of a bullet with your name on it; it's a spray of bullets or a speeding truck aimed at everyone in range.

Terrorism terrifies, as intended, because the deaths and maimings are horrific. Witnesses and emergency responders have to live with memories of sights they wish they never had to see.

Terrorist attacks feel randomly evil. The terrorist selects a place and a time, but to everyone else it can seem as out of the blue as planes crashing into skyscrapers on an ordinary September morning.

How do we handle the rippling anxiety that can leave us feeling powerless? What is the opposite of terrorism?

The National September 11 Memorial & Museum in the footprint of the fallen World Trade Center in lower Manhattan examined the response of New Yorkers and other Americans and themed the museum's permanent exhibitions around the response, not just the attacks.

What emerged to the museum planners was not only the overwhelming unity and compassion from first responders who risked and in many cases suffered death, but also from office workers who carried a disabled coworker many flights down to the ground, from people who brought food, and children who sent handmade cards. Everyone came together.

It was personal. People cared for and about one another by name and face. Biographies of each person who died fill an entire gallery at the 9/11 Museum dedicated to making sure they are never nameless statistics. They are noticeably of many ethnicities, races and ages, but that has no bearing on what happened to them. We can follow that example and refuse to treat people as categories.

No one who has seen the immediate horrible scene of carnage, or even pictures of it, wants those nightmare images to persist, but they do. We are made that way. Yet minutes after the attack comes the response and images of heroics like those of the spectators at the Boston Marathon bombings who saved many lives. Survivors and their doctors and nurses have shown immense courage and skill. Keep those images in mind.

Refuse to be chased into hiding or overwhelmed by anger or fear. The opposite of random evil is community, not isolation. Pray together, if that is your way. Terrorism's ultimate victory would be to change us into a people that cannot come together.

In the next few weeks the two national political parties will officially nominate their candidates for president. The campaigns and recent events have given a stark sense of a country that is challenged by anger, racism, violence and the inability to come to consensus. That is not terrorism, but it is not the opposite of terrorism either. It's not good enough as a response to those who would do us harm. 

This is a time to stand together.