The sounds you're hearing across the river in Cambridge this weekend are middle-aged men and women greeting each other with phony enthusiasm and feigned recognition.

It's called a 25th reunion, a rite of passage that faces all college graduates of, as they say, a certain age - a certain age, I must confess, at which I have now arrived.

Most frequently heard comment at a 25th reunion? ``You haven't changed a bit.''

Most frequently thought? Wow, have you aged.

Twenty-five years is a long time. Back then, Joseph Timilty was challenging Kevin White to become mayor of Boston.

And now? Timilty is running against White in yet another citywide race. But this time it's a son, Greg Timilty, against a daughter, Patricia White.

In 1978, we didn't time-shift, ``when the Berlin Wall falls'' was synonymous with ``when hell freezes over'' and we were all still angry with Richard Nixon. No one used a condom and when the president admitted he had ``committed adultery in my heart,'' we knew that's where it would remain. A cell phone was a call from jail.

Back then, the economy was in the tank, punk music was cool, traffic in Boston was a mess and the Sox were cursed.

OK. So some things don't change.

Like age, reunions creep up on you and then, with just weeks to go, the panic sets in.

You desperately start working out, trying to lose that 30 pounds you've added since graduation. You scour the shelves of CVS for the accouterments of beauty. Sunless tanning gels and Rogaine proliferate on the medicine cabinet shelves. There are covert trips for botox injections; you start to wonder how you too can join the Hair Club for Men and for the first time you start thinking about buying a girdle.

All of this, of course, is so that when you walk into the room, look around and wonder ``who are all of these old people?'' you aren't referring to yourself.

And ``who'' is often the issue. For despite the lies about how they haven't changed, they will have changed. Even if they hadn't, you wouldn't remember them anyway. College was a scant four years. Since then, six periods of equal length have come and gone. You may have known many but you stayed in touch with only a few. The rest are forgotten.

Not that you'd admit it. It's not proper etiquette at reunions to go up, look at the name tag and say things like, ``Did I know you?'' or ``Did we date?''

Instead, you fake it.

It begins with the reminiscing about the old times (``Heck of a snowstorm that year, huh?''). You pretend to remember when someone mentions some wild and crazy thing that you sure wish you'd done but think you were probably at the library instead. You bring up your own wild and crazy thing, embellishing as you go along, figuring everyone else has forgotten as well.

All of that's OK. But then you begin to stray into the danger zone of one-upsmanship. ``So, what have you been up to?''

``I'm leading the search for a cure for SARS.''

``Oh really? I'm a super-spreader.''

Like other rites of passage - such as your first root canal - it all sounds like a miserable time.

So why have reunions at all? Why not just exchange cards, maybe with those interminable here's-what-the-family-has-been-doing letters you typically get at Christmas (``and recently I've been exploring how Feng Shui can make for better baking!'').

I think it boils down to money: You have some and the college wants it.

My theory of higher education is that it's four years of training for a lifetime of giving.

The 25th reunion is designed to embarrass people at the peak of their earning years into proving they've been a success.

And what's the measure of success? None of us look better, for God's sake, and we can't even show off our kids since, in the full bloom of adolescence, they're most likely not talking to us.

But we can brag about money. And the college, cleverly, demands proof of the brag.

Apparently, it works. The 25th reunion is always a college fund's most lucrative.

My class, for example, has already coughed up over $13 million - which figures out, a fellow classmate pointed out, to almost $9,000 each.

That's a steep amount to simply be counted as average.

Still, cynicism aside, life is a journey with a destination you'd just as soon not reach.

Reunions are a marker along the way, one that causes you to step back a bit and do some hard thinking.

I won't be at the reunion, but to those I remember and the vast majority I never knew, I hope you're still enjoying the trip.

Tom Keane can be reached at tomkeane@tomkeane.com.