President Obama is at his best and most inspiring when he talks about who we are as a nation. When he pulls us out of the echo chamber of the Washington Beltway, cable television and the blogosphere to remind us of the greatness and the responsibilities of this enterprise called America. Yesterday’s speech on the national debt was one of his most inspiring. And it gives me hope that a consensus on dealing with it can be reached.

Obama made his case by stating and repeating his bedrock principles. In recounting how leaders came together three times in the 1990s to reduce the national debt, Obama presented his vision for meeting the same goal. “All three agreements asked for shared responsibility and shared sacrifice,” he said. “But they largely protected the middle class; they largely protected our commitment to seniors; they protected our key investments in our future.” After hammering away at the “Path” presented by Rep. Paul Ryan (R-Wis.) and tax cuts for the wealthy, Obama said, “To meet our fiscal challenge, we will need to make reforms. We will all need to make sacrifices. But we do not have to sacrifice the America we believe in. And as long as I’m President, we won’t.” And after presenting an approach he says will reduce the deficit by $4 trillion over the next 12 years, Obama said, “It’s an approach that puts every kind of spending on the table, but one that protects the middle class, our promise to seniors and our investments in the future.”

Finally, there are those who believe we shouldn’t make any reforms to Medicare, Medicaid, or Social Security, out of fear that any talk of change to these programs will immediately usher in the sort of steps that the House Republicans have proposed. And I understand those fears. But I guarantee that if we don’t make any changes at all, we won’t be able to keep our commitment to a retiring generation that will live longer and will face higher health care costs than those who came before.

Indeed, to those in my own party, I say that if we truly believe in a progressive vision of our society, we have an obligation to prove that we can afford our commitments. If we believe the government can make a difference in people’s lives, we have the obligation to prove that it works — by making government smarter, and leaner and more effective.

Obama spoke hard truths to the right and the left. To the right, he said reducing the deficit and national debt cannot realistically happen without tax increases or additional cuts in defense spending. More significantly, the president told the left that maintaining the status quo on entitlements would not help the nation’s fiscal situation either.

Obama defended his past decisions without sounding defensive. We’ve heard this history lesson on the nation’s economic mess, the attendant ocean of debt and the extraordinary measures he took. During the first two years of his administration, Obama would lay the blame squarely on the previous administration. Not yesterday.

But after Democrats and Republicans committed to fiscal discipline during the 1990s, we lost our way in the decade that followed. We increased spending dramatically for two wars and an expensive prescription drug program — but we didn’t pay for any of this new spending. Instead, we made the problem worse with trillions of dollars in unpaid-for tax cuts — tax cuts that went to every millionaire and billionaire in the country; tax cuts that will force us to borrow an average of $500 billion every year over the next decade.

The keyword being “we.” For the first time, Obama owned the crisis, which took the whine out of his “It was absolutely the right thing to do” defense of the extraordinary and unpopular measures he had to take in his first year.

Obama drew deep lines in the sand. Sure, he said, “So any serious plan to tackle our deficit will require us to put everything on the table and take on excess spending wherever it exists in the budget.” But he also made it clear he would only go so far.

On Ryan’s plan to end Medicare as we know it while maintaining tax cuts for the wealthy: “They want to give people like me a $200,000 tax cut that’s paid for by asking 33 seniors each to pay $6,000 more in health costs. That’s not right. And it’s not going to happen as long as I’m President.”

On renewing the tax cuts (“Bush” conspicuously absent from its moniker) for the wealthy: “But we cannot afford $1 trillion worth of tax cuts for every millionaire and billionaire in our society. We can’t afford it. And I refuse to renew them again.”

And now the fun begins. Obama has tasked Vice President Biden with working with congressional leaders to hammer out a final agreement by the end of June. But even the president acknowledges that the details of what he outlined yesterday might not be a part of it. “This is a democracy,” he said, “that’s not how things work.” True. And now that the president has joined the conversation started by Ryan with his own clearly stated principles and goals, democracy might actually have a chance to work.