It read like a manifesto for the new zeitgeist, a signpost for an America decking the halls with boughs of thrift and singing carols to the values of frugality:

“Perhaps it will be different now. Perhaps now is an opportunity to reassess what really matters. After all, if everything you ever bought her disappeared overnight, what would she truly miss?”

How charming. What a tribute to the collapse of consumerism, the one upside to the economic downside. The only problem was that this little gem of thoughtfulness was an ad for diamonds.

I have to tip my hat — reluctantly — to advertisers trying to rebrand upscale goods as virtuous in the face of stories heralding “Luxury Shame.” These days the media are full of people saying bye-bye to bling-bling. Blackstone Group’s Chair Steve Schwarzman publicly regrets that he spent $3 million on a birthday bash. A perfume mogul cancels a party at Four Seasons in favor of White Castle hamburgers at home. A “Secret Millionaire” on Fox’s latest, worst, reality show repents a private plane joy ride that cost $12,000 in jet fuel: “I feel like a fool for some of the money I’ve spent on some things.”

No, I won’t spend time worrying about people who are experiencing a long-delayed “embarrassment of riches.” These days, Change You Can Believe In is what’s jingling in your pocket. I’ll reserve my sympathy for the unemployed and foreclosed. But it’s worth noting when conspicuous consumption becomes self-conscious and frugality filters across the class structure.

For a long time, anyone writing about the gap between rich and poor, CEO and worker, was accused of fomenting class warfare. The middle class didn’t resent the upper class as much as it aspired to be upper class. Marketers even coined the odious term “aspirational consumer” to describe people who wanted to live rich. This over-the-head lifestyle was fueled by credit cards during a quarter-century of what economist Juliet Schor refers to as competitive consumption.

Now, competitive consumption has been replaced by contagious anxiety. Buying hit the wall with the housing collapse, the stock market plunge, the credit card crunch and the unemployment figures. “Thrift is the new normal.” “Sixty percent off is the new black.” Cutting back is in. Retail therapy is out.

This is, of course, a rational response to the worst economic crisis since the Great Depression. But when it affects people whose mortgages and jobs are secure, there’s something else going on as well.

Sociologists will tell you that the most powerful impetus to change is not a new discovery. It’s when you learn what you already knew. What Americans already knew at some level was that the credit-card-driven, debt-ridden, pay-later economy wasn’t sustainable. Not economically. Not environmentally.

It wasn’t just the Birkenstock crowd or our Depression-era elders who knew this. It’s been nestled in our collective subconsciousness among all the critiques against materialism, all the screeds against commercials, all the unease about excess and inequality, all the fear that we’ve filled our kids’ lives and landfills with stuff. But it was as commonly dismissed as a Sunday sermon. Or manipulated into a pitch for diamonds.

Today Schor, author of “The Overspent American,” says “There’s a common understanding that the party is over.” The common ethic changed on a dime. Or a 401(k) statement. There’s a recognition that we’re in uncharted territory. People who would have talked about their sex lives before their bank balance are now talking freely about free fall. “There was a sense of unease and now we can admit it,” says Schor.

The question is whether this thrift — a word that sounds like it was taken from “Poor Richard’s Almanac” — will last only as long as the credit crunch and the trendiness of the “recessionista.”

We’ve had booms and busts before. People shut their wallets after the dot-com bust and after 9/11. A New York Times piece with a headline “Thrift, Our New National Virtue” predicted that “the seeds of saving are sown. In the days to come thrift is bound to yield its good fruit.” That was in 1919, before the Twenties began to Roar.

But if it turns out that there’s something fundamentally different this time, it’s because we’ve maxed out on more than credit cards. There’s a dovetailing of economic and environmental — and human — values. If we repossess the words usurped by the De Beers merchants, “Perhaps there is something different now. Perhaps now is an opportunity to reassess what really matters.” It isn’t the diamond.

Ellen Goodman writes for the Boston Globe. Her e-mail address is ellengoodman@globe.com.