There is a time in the life of every boy when he for the first time takes the backward view of life,” Sherwood Anderson wrote in his 1919 novel, “Winesburg, Ohio.” Anderson added, “Perhaps that is the moment when he crosses the line into manhood.”

Anderson would have loved Friday’s Master’s Tea with Hanson.

In Branford’s common room, students crowded every patch of floor. My mind churned with the once-impossible things that had to be true for what I saw to be real. Hanson, whom I associate with middle school, is standing in the wood-paneled common room of one of Yale’s castles. Apparently, I grew up and now go to school there.

Silence gathered up the crowd as the once-icons of male pre-pubescence recounted tales of concert tours with wives and children, their battle with a homogenizing label, and their iTunes single “Great Divide,” whose proceeds combat AIDS. At the end, the brothers sang the chorus of “MMMBop.”

That 1997 pop hit — whose album sold 10 million copies, thieving the hearts of countless more pre-teen ladies — is the sound of fifth grade. It’s not that we really thought those days never would end. We just did not think about what would happen after, and who we would be.

Even when we were children, landscapes changed. But what stayed constant was a set of things only “other people” did: study and party in college; work a job; vote; live away from our parents; marry; go to friends’ weddings; raise children of our own; and, through all of these, do what we never could in middle school — live without fear. Yet last Friday, there we were, and there were the Hanson brothers, all of us older, and still around.

Now we find ourselves doing more and more of these things. We are becoming “other people.” We are now a generation, a title for which pop culture offers few higher coronations than to have one’s own oldies music. The stations that used to play Elvis and the Beach Boys now feature Bruce Springsteen and the Police, and soon they may introduce Third Eye Blind and Hanson. When they sang “MMMBop” at Toad’s, it already sounded like oldies.

For the first time, our lives include a complete, closed chapter. We cannot retrieve its times. There is someone we used to be who we cannot be again. The feeling seems to continue when you leave college. As the college grads sing in “Avenue Q”: “If I were to go back to college, think what a loser I’d be / I’d walk through the quad and think, oh my God, these kids are so much younger than me.”

Once, marriage was adulthood’s towering testament. No map revealed how to reach it. Other people were already there; we could barely see it. Marriage may still lie years in the future. But if you are in a relationship, and can imagine happily dating for a long while to come, possibly even after college, maybe the thought crosses your mind, once or twice.

The Hanson brothers are all married, and two have kids. How old does that make us?

To us Reagan babies, someone born in the ’90s must be a little kid. But even someone born in 1991 is now 16, old enough to operate a motor vehicle.

Meanwhile, we scramble to find summer jobs, knowing that soon enough, jobs will not be a break from the year’s routine — they will be its center. We are supposed to do something in this world, and we want to, but it is hard to know what.

I voted for the first time last fall. Standing in the public library’s booth, I thought, “Uncle Sam, do you realize you’re entrusting civic duty to someone who lists ‘Happy Gilmore’ as one of his favorite movies on Facebook? Don’t you want to tell me how to choose?”

I made my choice, slid the appropriate sliders, thanked the lady at the library and walked away onto the dusk-lit Green.

We are startled by the anarchy of choice. High school was a practice round for college, a place of strategies and goals. College students were “big kids.” The grown-ups who ruled us were even more a different species. College, too, has a purpose. It is a practice round for the “real world,” before we become “big” 30-somethings.

One wonders if maybe the “real world” is a place without warnings and instructions, free of rules and purposes, no place to practice for the future, simply a place to be in the present. One imagines a world where nobody is big, not even 30-somethings. We are all just people. In this time God has given us, we vote, marry, work, rent apartments, come to know each other and do all the things people do, simply because we wish to, as long as this time lasts.

Yale, as much as a place to acquire knowledge, is a place to experience this transformation in the company of friends. Behind the simple fun of the recent “Crushes and Chaperones” dance, Out of the Blue’s “Prom” and Slifka’s “Faux Bar Mitzvah” lies the ricocheting mental energy of friends processing this change.

Amid all we lose, we keep that energy, and these friends. When we gaze up at Yale’s Gothic architecture, wondering who we want to be, we pour our feelings into those buildings. We will come back for reunions to this place. The feelings will spill back into us. To the new Yalies, we will be old, but to us, we will simply be ourselves, as generations of alumni have felt — including those we think are old.

Maybe as we drive to our New Haven hotels, we will put on the oldies station. “MMMBop” will still get stuck in our heads.

Noah Lawrence is a sophomore in Saybrook College. His column appears on alternate Mondays.