It was a beautiful day, that’s what everyone remembers. So clear, so crisp, so bright. It sparkled as I walked my 14-year-old son out to go to the subway that would take him to his new high school, in Brooklyn. He was now a commuter: a walk to the 86th Street subway station and then the 4 or 5 train downtown near the towers and over the river. That was about 7:30 in the morning. It was beautiful at noon when I went to mass at St. Thomas More church on 89th Street. And between those two events, his departure and the mass, the world had changed, changed utterly. After mass, at the rise of 86th Street, the day was so clear you could see all the way downtown to the towering debris cloud.

But it was beautiful. That was one of the heartbreaking elements.

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The things I will never forget. Looking up at a silent TV screen as I returned email at my computer. Seeing a long-distance shot of the World Trade Center with smoke coming out of the side. Putting up the sound. Hearing a food cart vendor with a heavy accent saying to a reporter on the scene: “That was no small plane, that was a big jet, a jumbo jet.” Knowing it was true. Hearing the TV chatter that a pilot might have accidentally hit the tower. Knowing it was not true. Grabbing the phone to call my son’s school to make sure he had arrived, that he’d gotten there safe, that he hadn’t tarried or gotten off downtown to walk around because it was a beautiful day. Busy signal. Again. Busy. Calling a friend whose husband often worked downtown. No, she said, he’s in London. Talking with her as we watched the screen together and then the second plane went in, right before our eyes, and there was no denying what it was. Calling school. Busy. And then the phones went down.

And then the buildings fell. That was the thing, they heaved up and groaned to the ground and brought a world with them. We could have taken it if the buildings didn’t fall. That’s why the day was so uniquely a New York trauma, for all that happened in Washington and Pennsylvania: The buildings went down and we saw it. My friends saw the jumpers, who fled the flames. To this day they don’t talk about it. My friend saw the faces of the passengers on the first plane, so low did they fly by his building. He saw their faces in the passenger windows. He never told anyone about that, including his wife, until two years ago.

Hearing that that 20,000 or 30,000 people might have been in the buildings. Hearing something about the firemen—a lot of them died, a lot of them tried to charge up the stairs to the fire. The man standing on line in Murphy’s Market after mass. He was covered in Pompeii ash. He had walked uptown. He was standing there in shock with a bottle of water and a banana. The bad boys who hung out near a local school and were said to sell drugs: They took their big boom box and put in on the steps so people walking by could sit down and hear what was happening. I sat down and listened and when I left I said, “Thank you, gentlemen,” and they nodded because they knew: They’d been gentlemen.

And, funnily, such a blur of images so vivid that years later you think you actually saw them when you didn’t. A few days after the attack, I read of someone seeing a transit worker or policeman in a car downtown, parked and motionless, and he had on the radio and it was blaring “Heroes,” and he was crying. I remembered it a few years later and found the Peter Gabriel version. “I can remember / Standing by the wall . . . And we kissed as if nothing could fall . . . We can be heroes . . . just for one day.” It still makes me weep, and when I hear it I see the transit worker or cop again, even though I never saw him.

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Worried sick about my son and no way to reach him. And then miraculously the dead phone rang, at 3 p.m. My 14-year-old on the line at the phone at the school that was working that moment, other students crowded behind him. I am fine, he said, but we still don’t know everything that happened, tell me what you know. “It was Arab terrorists,” I said. And he muffled the phone and I heard him announce to the kids, “It was terrorism, an Arab group.”

“It appears to be over,” I said.

“The attack is over, it appears to be all over,” he said. On it went as I filled him in and he filled them in. He told them the towers and the Pentagon were hit but not the State Department, that was a rumor. He was calm, collected, in the middle of history.

He told me he would not get home tonight, all the bridges closed and public transportation stopped, he’d stay over, with some Manhattanite students, at a teacher’s house, he’d be home some time tomorrow, he’ll be fine, don’t worry.

He made it home the next day about noon. And he told me what he’d seen. The subway from Brooklyn to the city curved up over the East River, and everyone on it always turned to look at sparkling, majestic downtown Manhattan. And this day they all turned and they saw the dead cloud, the lost empty buildings, and they all went Oh. A long soft sigh: Oooohhhhh.

There is an unwritten story in how brave our children were that day, and have been since, and what that day was to them. But those who were adolescents or early teenagers on 9/11: they never talk about it. They took it all in but they never talk about it.

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As for me, I notice that in the early years after 9/11, when they did their replays of the event on the news, I always used to watch with some kind of pain that was being worked out while it was being re-experienced. But now I can’t watch. Because it causes some kind of pain that is not going to be worked out, and that has to do more with what followed that day than the day itself.

But I want to end with the beauty of that day, and a parallel. I have been reading Paul Fussell’s “The Great War and Modern Memory.” He notes that those who were there remembered the summer of 1914, the months just before the start of World War I, as the most beautiful of their lives. Bright, clear, stormless—no sign of the harrowing trenches just around the corner, of the 7,000 a day who would be wounded or killed on the Somme alone, among British troops alone. “All agree that the prewar summer was the most idyllic for many years. It was warm and sunny, eminently pastoral.” For the great writers who would fight the war, it was carefree, innocent. Siegfried Sassoon “was busy fox hunting,” Robert Graves climbing mountains in Wales, Wilfred Owen tutoring French boys in English near Bordeaux. “For the modern imagination that last summer has assumed the status of a permanent symbol for anything innocently but irrecoverably lost.”

Like that beautiful September day, like dawn on September 11, 2001.

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So that was my 9/11. The boy who returned, the world that was ended, the pictures that will never leave your mind. Like this one: A few weeks later I was pouring coffee for construction workers at St Paul’s church downtown and a guy came in and introduced himself. He was a member of the Iron Workers Local 40. They were dismantling the bottom of the towers. He read my columns online, he said. He took his coffee and came back later and in his hand was a paper bag and in the bag were a heavy little heart and a heavy little cross, just cut from the north tower. “I want you to have these,” he said. As I write they are on my desk, in front of me, burnt and bent but there.