09/10/2012 02:53 pm ET Updated Nov 10, 2012

That Other Day

You're at the World Trade Center at about noon on the Sunday before. You're with your wife and daughter. You're all sitting under blue skies at the fountain in the plaza between the towers.

People from all over the world surround the fountain. The spray glints in the sunlight, the sound almost a shushing. Dogs lap at the ripples. Little kids splash around.

It's a perfect day, the sort of day that makes you believe with all your heart that nothing bad could ever happen to any of us, that nothing could ever go wrong, least of all here. A glimpse of paradise -- everyone feeling safe, at peace.

Later will be different. Later everything will change.

Later, on that next Tuesday, you will leave your office in midtown Manhattan at dusk, more than 12 hours after everything changed. And as you walk home from the subway, along Queens Boulevard in Forest Hills, Queens, you will see a woman standing on the sidewalk in front of an apartment building holding a lit candle. Just standing there in public silently holding a lit candle aloft.

You will feel tempted to say something to the woman. You will want to ask her why, to ask if she lost someone that morning, to tell her you're sorry. But you wish to respect her right to grieve in privacy and decide to let her be.

Later, over the next few days, you will go to the roof of your 22-story building in Queens for a view southwest, toward lower Manhattan. And there, miles and miles away, across all the rooftops and the East River, you will see the massive ruins still smoldering.

Later, in the following weeks, you will hear about Michael Lomonaco, the executive chef at Windows on the World. You and your wife frequented the restaurant at the top of the World Trade Center a few times for special romantic dates in the early years of your marriage. You would get to know Lomonaco a little through your job and come to like him. He entered the World Trade Center about 30 minutes before the first airliner hit the north tower. But rather than take the elevator to his office on the 107th floor, his usual routine, he visited an optometrist in the ground-level mall to get his glasses fixed. That decision almost certainly saved his life.

Later, too, after everything changed, you will publicize a book titled You Can Do It! The Merit Badge Handbook For Grown-Up Girls, authored by Lauren Catuzzi Grandcolas. Lauren planned an inspirational book that would teach girls and women new skills. But she happened to be a passenger on United Flight 93 that Tuesday, which was hijacked and then crashed in Pennsylvania, killing all aboard. She was pregnant with her first child. Her two sisters finished the book to honor her memory, and through your efforts appear on national TV to tell her story.

Later, more than two years after that Tuesday morning, you will get the privilege of promoting the newly created World Trade Center Health Registry. The goal will be to motivate survivors at or near the site of the attack to enlist in a 20-year study of physical and mental health effects. You team up with the Centers for Disease Control and Prevention and the New York City Department of Health And Mental Hygiene. You play a minor role in helping to draw more than 71,000 enrollees, making it the largest post-disaster public health registry in United States history.

Somehow, then, you stay connected to that Tuesday morning for the next 11 years, as if it's inescapable.

But all of that will be later. Right now it's still the Sunday before -- that Other Day -- and all of that has yet to happen. All you know is this moment, the tranquil hiss of the fountain, the giggling of toddlers and the yipping of puppies, the miracle of it all, of life here in New York City, in the United States Of America, with your wife and daughter. Safe. At peace.

That Other Day is the day you choose to remember. It's when you came to the fountain for the very first time, with no idea that it would be your last, no idea at all that innocence seldom remains intact, that perfect never lasts. It's when we all still had what we later lost. That Other Day is the day you refuse with all your being to forget.

Bob Brody, a public-relations executive at Powell Tate and an essayist, lives in New York City and blogs at