The President almost seemed apologetic. "This may be a slightly longer speech than I usually give,” he told his audience at Georgetown University on April 14.

"This is going to be prose and not poetry.” What followed, as promised, was not poetry. Barack Obama doesn’t do much poetry anymore.

But in prose that was spare and clear and compelling, the President proceeded to describe how his Administration had responded to the financial crisis, the overriding challenge of his first 100 days in office. He had covered this ground before, nearly as well, in his budget message to Congress.

But now Obama went further, using a parable from the Sermon on the Mount — the need for a house built on rock rather than on sand — to describe a future that was nothing less than an overhaul of the nature of American capitalism.

"It is simply not sustainable,” he said, "to have an economy where, in one year, 40% of our corporate profits came from a financial sector that was based on inflated home prices, maxed-out credit cards, overleveraged banks and overvalued assets.

That was the house built on sand. His house built on rock had five pillars — new rules for Wall Street, new initiatives in education, alternative energy and health care, and eventually budget savings that would bring down the national debt — which did sound a bit prosaic.

Democratic politicians have been promising one or another, if not all, of the above since Franklin Roosevelt reinvented American government in the 1930s.

But Obama was making his case in the midst of a national crisis, at a moment when it seemed possible that he might enact much of what he was seeking. And he was talking about far more than a new set of policies: he was implying a new set of national values.

"There’s also an impatience that characterizes [Washington],” he said, "that insists on instant gratification in the form of immediate results or higher poll numbers. When a crisis hits, there is all too often a lurch from shock to trance, with everyone responding to the tempest of the moment until the furor has died down ... instead of confronting major challenges that will shape our future in a sustained and focused way.”

The combination of candor and vision and the patient explanation of complex issues was Obama at his best — and more than any other moment of his first 100 days in office, it summed up the purpose of his presidency: a radical change of course not just from his predecessor, not just from the 30-year Reagan era but also from the quick-fix, sugar-rush, attention-deficit society of the postmodern age.

The speech received ho-hum coverage on the evening news and in print — because, I suspect, it was more of a summation than the announcement of new initiatives. Quickly, public attention turned to new "tempests of the moment” — an obscene amount of attention was paid to the new Obama family dog and then, more appropriately, to the Bush Administration’s torture policy and the probably futile attempt to prosecute those who authorized the practices.

And then to a handshake and a smile that the President bestowed on the Venezuelan demagogue Hugo Chávez. These are the soap bubbles of our public life. They have become the hasty, capricious, bite-size way that we experience the world. It has made for slovenly, sandy citizenship.

The most important thing we now know about Barack Obama, after nearly 100 days in office, is that he means to confront that way of life directly and profoundly, to exchange sand for rock if he can.

Whether you agree with him or not — whether you think he is too ambitious or just plain wrong — his is as serious and challenging a presidency as we have had in quite some time.

The idea that a President can be assessed in a mere 100 days is a journalistic conceit. Most presidencies evolve too slowly to be judged so quickly.

Roosevelt set the initial standard in 1933, overpowering Congress and passing a slew of legislation to confront the Great Depression during his first three months in office.

"Lyndon Johnson had two 100-days periods,” says historian Doris Kearns Goodwin, "one after the Kennedy assassination and another after he was elected in 1964.”

Indeed, Johnson’s legislative haul dwarfs anything before or since; he quickly got Congress on track to pass landmark civil rights bills and create Medicare, among other things.

"And you have to say that Reagan had a significant 100 days,” Goodwin adds, "because he represented a clear break from the policies of the past, even if his signature legislation — the tax cuts — didn’t pass until after the 100 days were over. But I don’t think we’ve ever seen anything like Obama since Roosevelt.”

The legislative achievements have been stupendous — the $789 billion stimulus bill, the budget plan that is still being hammered out (and may, ultimately, include the next landmark safety-net program, universal health insurance).

There has also been a cascade of new policies to address the financial crisis — massive interventions in the housing and credit markets, a market-based plan to buy the toxic assets that many banks have on their books, a plan to bail out the auto industry and a strict new regulatory regime proposed for Wall Street.

Obama has also completely overhauled foreign policy, from Cuba to Afghanistan.

"In a way, Obama’s 100 days is even more dramatic than Roosevelt’s,” says Elaine Kamarck of Harvard’s Kennedy School of Government.

"Roosevelt only had to deal with a domestic crisis. Obama has had to overhaul foreign policy as well, including two wars. And that’s really the secret of why this has seemed so spectacular. To be sure, the historic unpopularity of the Bush Administration has been a convenient foil for Obama.

He has also been lucky in his enemies, a reeling Republican Party that lurches from gimmicks to hissy fits, including frequent, unbidden appearances by such unpopular characters as Karl Rove, Dick Cheney and Newt Gingrich, whose rants about everything from Obama’s decision to repudiate the torture of enemy combatants to his handshake with Chávez seem both ungracious and unhinged.

"We obviously haven’t found our voice yet,” says Senator Lamar Alexander, one of the more thoughtful GOP leaders.

"The American people sent us to the woodshed. And when you go to the woodshed, the best course of action is to sit there, be quiet, figure out why you’re there and what you can do about it.”

Perhaps Obama’s most dramatic departure from the recent past is his public presence: cool where George W. Bush seemed hot, fluent where Bush seemed tongue-tied, palliative rather than hortative.

Bush would never admit a mistake, but Obama said the words plainly — "I made a mistake” — when his appointment of Tom Daschle as health-care czar tanked, one of the few significant setbacks during his time in office. (One senses that Obama’s cool can quickly turn chilly.

"He is not very sentimental,” says an Obama aide. "If you’re no longer useful, he’ll cut you loose.”) The President’s willingness to speak candidly about American failures when he travels at home and overseas — Wall Street’s role in launching the financial crisis, for example — has annoyed Bush stalwarts, but it has opened the door for a new, cooperative foreign policy that is as dramatic a break from the past as the domestic initiatives Obama described in his Georgetown speech.

With the exception of Johnson’s remarkable run, the few successful 100-day sprints have been a triumph of vision over substance.

Roosevelt, Reagan and Obama changed the national mood more than anything else — and moods can change back quickly, especially in our overripe, overwired cable-news dystopia.

As impressive a start as Obama has had, these 100 days could come to seem an overambitious and naive presage of disaster if the President’s financial policies are inadequate to meet the crisis; his budget proposals are gutted by Congress; and his attempts to leave Iraq, fight in Afghanistan and negotiate with the Iranians turn sour.

"Those of us who are older and more scarred have to be skeptical about all that Obama is trying to do,” says William Galston, a Clinton White House policy adviser.

"If he’s right, our traditional notion of the limits of the possible — the idea that Washington can only handle so much at one time — will be blown to smithereens. If he’s wrong, he may be cruising for a bruising on a lot of things. Then again, there’s a third possibility: that this is the best negotiating strategy attempted by a Democratic President in a long time and he’s angling for only a portion of what he has proposed. But I think he wants it all.”

The fate of Obama’s first year in office, if not his Administration, will probably be determined by the way he handles four distinct challenges — two in foreign policy and two domestically. The domestic challenges are more important, given the financial crisis. One is whether the financial community will buy his "house built on rock” formulation.

"I don’t think the banking community understands the scale of the damage that they’ve done to this society,” says a senior Obama financial adviser. And another says, "They’re in denial.

They don’t understand how angry people are about a $1 million bonus.” If the bankers and corporate executives don’t understand the need to modify their behavior, Obama’s financial plan could come crashing down.

There is a mini-rebellion going on right now among executives, from JPMorgan Chase & Co. to Chrysler, who don’t want to take government loans because they won’t be able to gorge on their usual bonuses.

"The plan to buy up toxic assets is going to evolve very slowly, if at all,” an investment banker told me. "The banks don’t want to take the haircut, and the hedge-fund managers” — who would partner with the government to buy the assets — "are afraid that if they start making big money on this, Congress is going to whack them the way it did on the AIG bonuses. If this plan doesn’t work, it’s going to take a much longer time to get out of the recession. And if it takes longer to get out of the recession, the President won’t have nearly the revenues he needs to fund his domestic priorities.”

And that’s the second domestic challenge: the realization that Congress will not give Obama everything he wants. Aides say the President’s moments of frustration almost always have to do with Congress.

"We know that not every wagon makes it across the frontier,” says a top Obama adviser.

"But we’re not willing to decide yet which wagons are going to make it and which aren’t.”

In fact, that decision seems more and more apparent: Congress is unlikely to pass the linchpin of Obama’s alternative-energy initiative — a cap-and-trade program for carbon emissions to combat global warming and tilt the market toward energy independence but that would also raise energy prices in the midst of a recession.

"The wagon that needs to get through is health care,” says a second Obama adviser, picking up the metaphor. But that won’t be easy either — unless the Obama Administration can lure some Republicans to support it, which might be possible if the plan relieves the pressure of health-care coverage on corporate America.

"If he narrows his agenda to fixing the banks and focusing fully on health care,” says Senator Alexander, "there’s a good chance we could get it done.”

If the rest of his agenda is trashed but Obama emerges with universal health insurance, the achievement will be historic.
There are other challenges.

Defense Secretary Robert Gates has submitted a radically sane Pentagon budget, which eliminates some unneeded weapons systems — and is likely to be eviscerated by members of Congress from the districts where those systems are built.

"We are absolutely going to stand with Gates on this one,” said an Obama aide, implying that the President would veto a same-old defense budget.

Gates is considered a major success within the Administration, as is the straight-talking Secretary of State, Hillary Clinton.

There is some concern, however, about National Security Adviser James Jones, who is still adjusting to civilian life after a brilliant career in the military.

"Obama has appointed all these high-powered envoys like [Richard] Holbrooke and [George] Mitchell, but we don’t know who’s going to really be in charge of setting the foreign policy priorities,” says a prominent foreign policy realist who admires Jones.

"That should be Jim’s job. But he’s throwing off a sense of uncertainty.” Several sources say Jones seems to attend meetings rather than lead them.

"He needs to drive the agenda,” the foreign policy expert adds. "He has to be first among equals — the fact that Condi [Rice] couldn’t control Cheney and [Donald] Rumsfeld in Bush’s first term was disastrous. A lot depends on what sort of relationship develops between Jones and Obama.”

The second big foreign policy challenge is the natural conflict between the demure slog of diplomacy and the need for the American President to be a strong leader who sets the international agenda.

"The one thing Obama hasn’t done in the first 100 days,” says Zbigniew Brzezinski, who was Jimmy Carter’s National Security Adviser, "is the big Middle East speech where he says, ‘This is the settlement. This is what we’re for.’

If he doesn’t do that soon, [Israeli Prime Minister Benjamin] Netanyahu is going to set the agenda, not us — and that will be a disaster. If we don’t act now, any chance of a two-state solution will be gone. If he does act now, every government in the world will stand with him.”

Except, perhaps, the Israelis and their American supporters in the Jewish and Evangelical communities. Obama’s willingness to override domestic politics for the greater good will be a major test.

In a way, Brzezinski’s stark choice is emblematic of the problem that Obama faces now that his first 100 days is nearly complete. There are those who mistake his quiet, deliberative style for softness.

There is the fear that he won’t have the strength to stand up to the Israelis (or the Iranians) or to the left wing of his party on health care or to the porkers on the defense budget. On the other hand, there are three dead Somali pirates who attest to this President’s ability to make tough decisions in a timely fashion.

Obama won’t stand up to everyone, always; he is, after all, a politician. But the quality of fights he does choose will determine whether he builds his legacy on rock or sand. He has had a brilliant time announcing his intentions, but the real game of governing is about to begin.

TIME