By now there are so many sports metaphors littering the campaign coverage that it's hard to tell CNN from ESPN. The Pennsylvania primary not only had its wrestling matches and boxing rings and slam dunks but almost turned pinochle into a contact sport.

But let us take a minute to replay the seniors event. It was the over-60 crowd that helped Hillary wrestle (sorry about that) her 10-point victory in Pennsylvania. Voters over 60 chose Clinton by 62 percent to 38 percent. That's almost the mirror image of voters under 30 who chose Obama by 60 to 40. In some actuarial twist, every birthday between 30 and 60 sent more voters into the Clinton camp.

Go figure. The quality that mattered most to exiting voters all across the age spectrum was who "can bring about needed change." Yet the two groups on either end of the voting-age bell curve picked opposite change agents. Is there a clue to this grueling race? Does it swing on the idea of how we make change?

The Obama and Clinton campaigns have been long characterized as "hope" and "experience." Their notions of change come out of their life stories.

Sen. Clinton might well have been an Obama girl at Wellesley. Even in 1992, the Clintons were the new kids on the block, the "don't stop thinking about tomorrow" couple. Bill was the man from Hope, the cross-cultural candidate who combined traditional values with liberal goals. He preached a "third way" on policies such as welfare reform.

But in Washington, he walked directly into the right-wing propeller. Two years later, we had the "year of the angry white man" fueled by radio talk show hosts and Newt Gingrich. That year, George W. Bush became governor of Texas by beating Ann Richards, and Hillary Clinton replaced Ted Kennedy as the piñata of the Republican fundraisers.

What did she learn from this? That you have to wrest change, inch by inch, bill by bill — and sometimes from the cold, dead hands (may Charlton Heston rest in peace) of the right wing.

What did Sen. Obama take from his life lessons? A child of two races and cultures, he grew up with a strong motivation and talent for building bridges. Obama was raised by the mother who was an anthropologist, not the father whose own hopes and ambitions were thwarted by lingering tribal enmities. He made his way from Hawai'i to Harvard Law School riding the cusp of change.

As a community organizer, he worked in the high end of the grass roots. In this campaign he seems to dismiss the Clinton years as just another chapter from the old annals of food-fight politics. A pox on both houses. Obama believes, as he said again Tuesday night, "real change doesn't begin in the halls of Washington, but on the streets of America. It doesn't happen from the top down, but from the bottom up."

It's not news that both these candidates share the same fundamental goals. But one believes that change is fought for in a kind of trench warfare. The other believes that it can come in a transforming wave. And in some ways, this whole primary contest is over which way Democratic voters believe the political world really works.

I'm not suggesting that people are consciously parsing their philosophy of change at the polling booth. The last two standing Democrats have great personal strengths and not a few flaws. Ironically, both represent the changes we talk about.

But this tale of two change agents folds into a central narrative of the primary, including the unresolved, in fact, unresolvable question about which candidate is better poised to run against John McCain. Will the main election be a tough slog from one attack ad to the next? Hillary, anyone? Or can Democrats energize an overwhelming wave that drowns the Republican opposition? Do I hear Barack?

To some, hope is just another word for naivete. To others, experience is an excuse for cynicism. What people believe about this seems to fall along the actuarial table.

So Pennsylvania was a senior event in the extreme sport of politics. But it wasn't just Hillary's resume that won her the "experience" vote. It's the memories of many who lived through those wonderful yesteryears from "Willie Horton" to "Swift boat."

For the moment, older voters are singing a refrain from the "Music Man" song, "the sadder but wiser girl is the girl for me." In Pennsylvania, their experience kept Hillary's hope alive.

Ellen Goodman is a columnist for The Boston Globe. Reach her at ellengoodman@globe.com.