On the morning of September 11, 2001, I was sitting at my dining table, enjoying a cup of coffee. I lived in Brooklyn Heights, about two blocks from New York Harbor. I heard a loud crash, and my first thought was that there had been a terrible automobile accident on the Brooklyn-Queens Expressway, a highway bordering the harbor. Nothing I could do about it. I kept sipping my coffee.

A few minutes later, my partner Mary called to say that a small plane had crashed into the top of the World Trade Center. “Turn on the TV,” she said. She thought it was not an accident. She thought it was terrorism.

I turned on CNN and saw the smoke billowing from the top floors of the north building of the World Trade Center. I grabbed one of our two dogs–(our rescue girl, Lady, a big white Cocker Spaniel)–and headed for the waterfront, some three or four minutes away.

As I got to the waterfront at Grace Court Alley. a tiny block that leads to the harbor, I looked up and saw the second airplane slice into the second WTC building. This was not a small plane. It was not an accident. It was terrorism. I stood there speechless, alongside a couple of others who were there for the same reason as I. We wanted to see for ourselves. And in an instant, we all knew that hundreds and thousands of people were dying as we silently watched.

I ran back home to see what CNN was saying. I could see what was happening with my own eyes, but needed to know more to put it in perspective. CNN filled out the picture. Two large jets hit the two buildings, minutes apart. We did not know at that moment that another jet was on its way to hit the Pentagon and that a fourth jet would crash in Shanksville, Pennsylvania, when brave passengers fought the terrorists and sacrificed their lives.

At the WTC, fire fighters were on the scene, racing up the stairs to try to save people. People in both buildings were told to stay in their offices and wait for help. Most did, assuming that the fires would be put out. The elevators were out of service.

Those on the highest floors had no exit. The elevators weren’t available, and the stairs were filled with smoke. After it was over, word came out that one stairway was not blocked but I don’t know if that was true or if there was time to run down more than 100 flights before the building collapsed.

Some people on the high floors jumped to their deaths, not wanting to die of fire or smoke inhalation. Thank God I was too far away to see them jump to their deaths. People in the buildings were calling their families to say goodbye. So many phones were in use that cell service was intermittent.

But one after the other, the buildings collapsed, pancaked. Almost 3,000 people died, people of many different nationalities, including about 60 Muslims. So did 343 fire fighters, racing up to high floors to try to save those who were trapped. Since 9/11, more than 400 other firefighters died of injuries sustained that day or cancers related to the site.

The first person to die was Father Mychal Judge, a beloved Fire Department chaplain, who was outside the first building to be hit. He was crushed by the body of someone who had jumped. Father Judge was a saintly man.

After the two buildings collapsed, Mary came home from work, and we went to the nearest hospital, hoping to donate blood. The hospital would not accept it. No victims were brought in. None. Blood was not needed.

All transportation came to a halt. Subways stopped. Public buses stopped. The bridges connecting Manhattan to other places were closed to vehicular traffic. The only sound was the intermittent roar of military jets.

Our friend Bernadette attended a meeting that morning on a low floor of the WTC. She tipped the attendant at the garage to leave her car near the entrance, so she could leave quickly. After the attack, she pulled out of the WTC garage, picking up as many people as she could carry, and was the last car to cross the Brooklyn Bridge before it was closed.

We walked past the Brooklyn Bridge and saw scores, hundreds of people crossing it, from Manhattan to Brooklyn. They looked shell-shocked. They were covered in ash, which floated everywhere. Some were barefoot. Some carried sooty briefcases.

We watched the smoke pour out of the tops of the buildings before they collapsed. After they collapsed, there was a thick plume of smoke from the places where the buildings had stood. The wind blew steadily from south to north, away from us.

After a while, the wind shifted to the east, where we were. We could no longer see “the pile,” as the gigantic burning hole was called. What had been a brilliant blue sky turned dark and smoky. We could no longer see anything. Not the sun, not the clear blue sky.

The next morning, there were ashes everywhere in the neighborhood, ashes blown in our direction after the winds turned east. Cars and streets coated with ashes.

In our small backyard we found papers–memos, documents, letters, reports–a day earlier, they had been on someone’s desk. Now they coated our yard, unremarkable except for the tiny burn holes in them.

The pile burned for weeks afterward. We could see the smoke curling up towards the sky. We could smell it–a strange and acrid amalgam of burnt plastic, burnt metal, burnt lives.

We wanted to get out of town, drive far away. But the lines at the gasoline stations were long, and many stations had no gasoline. The city was silent, an eerie silence, not the usual hum.

For months afterwards, I couldn’t fall asleep at night. I imagined the terror of those trapped on the high floors. I felt their terror and panic.

I remembered the wonderful events I had attended at Windows on the World, the spectacular restaurant on top of one of the buildings. No one on those floors–the 106th and 107th–survived.

I will never forget those days, weeks, months. It didn’t happen to me. I was spared. It happened to all of us. Violence begets violence. Hate begets hate.

As W. H. Auden wrote almost a century ago, “We must love one another or die.” He wrote in another version of the same poem, “We must love one another and die.”

Both versions are right. More hate means more violence and death.