We don’t see gradual.

I looked up one day from our intense preparation for his college departure and realized, he was already gone.

Our parent's generation doesn't seem to understand. Somehow my departure from the stage wasn't such a cataclysmic event.

When they say "What's the big deal, no one died" I want to shake them and say "you don't understand, I'm just gonna miss him, his presence, the pleasure of his company."

I am trying not to be overly dramatic about the first one leaving the nest, but even the most hard-bitten friends have talked about the emptiness that comes when they do.

“It’s like they cut a hole in your heart,” according to friend I would call, unemotional.

Nothing ages you like your children's passages. When you send them off to college and realize the clock really is ticking, not on them, but on you. It forces us to think about all we are in the midst of: Jobs, marriages, friendships, life.

In a much passed-around article, columnist Michael Gerson compared dropping his child off at college with the ending of the universe. He notes that Cosmologists, who I thought gave facials, “assure us, our sun and all suns will consume their fuel, violently explode and then become cold and dark. Matter itself will evaporate into the void and the universe will become desolate for the rest of time.”

Okay, that’s dramatic, but only a little.

We started preparing early, at the start of senior year, a time everyone told us would be a disaster. But it wasn’t. The college application process, the waiting, the pull and push of a teenager trying to escape childhood and parents trying to keep order.

Everything flew generally on time and according to plan.

And then one night a few weeks ago I headed upstairs to drop the new copy of Sports Illustrated on his bed and found myself in the center of his empty room. There were lots of days like this, with work, friends, and his own angst changing the household routine, I would leave before he was up and he was out when I went to bed. His job as an 18-year old waiter conflicted with my schedule as a human. I could go days without seeing his face.

I hadn’t been in his room in weeks. It used to be a regular hang out. At first to tuck him in, read a book, make sure he was asleep, then make sure he was home. It was a place where serious talks took place and stories were told in the confidence of darkness.

And now I stood in a foreign zone, duffle bags splayed open like patients on an operating table, packages of t-shirts and socks, various dorm room requirements, fresh toiletries still in their packaging. Along the perimeter was his past. An outer ring of memorabilia that tracked his childhood:

A baseball glove, a collage of pictures with kids from another neighborhood, stacks of books from various years, Narnia, To Kill a Mockingbird, The Road. Some are dog eared, some un-cracked. Old bobble heads, long-forgotten ticket stubs, a sea shell, baseball caps of all sizes, a faded art project, a piggy bank stuffed with pennies, a replica of the Forum, an empty Coke bottle from Israel, a deconstructed science project.

A friend of mine calls this a “memory minefield.” These places that shake us with their history, of a time that no longer exists.

I look for them in every room, every block of our neighborhood, every memento. The school, the restaurants, a dent on the couch, things from a different era, when the house had a different rhythm. Gerson said that parenthood is a lesson in humility: “The very best thing about your life is a short stage in someone else’s story.”

Hunting around these corners, preparing myself for these moments, I realized that while I was still on stage, he was already gone. Off on his new adventure, while I am here with the memories, a minefield for me, a past for him.

There are any number of quotes about London that come to mind as we leave. But this best represents the sentiment:

"If you are lucky enough to have lived in Paris as a young man, then wherever you go for the rest of your life, it stays with you, for Paris is a moveable feast."--Hemingway

London is the new Paris.

It was before seven in the morning a few weeks ago and the captain said we were landing at Heathrow. He said it in the way they say it, two words, Heath--Row. And my stomach was excited in a new way, all the thrill of going home coupled with the anticipation of being away.

We would only be in London for 10 days, some final clean up at the office, pack up the apartment, attend the Olympics. And ten days later the call from the stewardess was "We are arriving in Dulles Washington" as she called it. It didn't have the same appeal.

I’ve tried to identify the emotion we are experiencing. Why can't I put my finger on what it was that I felt when I closed the door on that house and this year?

It is an ending. It’s not a movie or a vacation or a restaurant we can return to. It's most akin to the end of college.

I can go back to Ann Arbor, but not as an 18 year old. I can walk down State Street but the bars are filled with different students making their own memories. There isn't a Sammy house full of brothers, those aren't my books, my beer, my teachers or my first taste of freedom. They now belong to someone else. Only the memories are mine.

So yes, we’ll go back to London. And we'll even return to 9 Abbey Gardens, but not as a resident. We'll never stay in that neighborhood as a neighbor. And in the end that's what makes me long for it, as I did when I left anything for the last time and it was termed a Commencement: Because you can go home again, but sometimes the home isn't there, just the house is.

Thoreau said when he left his cabin on the shores of Walden Pond: “I learned this, at least, by my experiment; that if one advances confidently in the direction of his dreams, and endeavors to live the life which he has imagined, he will meet with a success unexpected in common hours."

And so we return to the common hours.