The Russian poet and novelist Boris Pasternak observed that "history cannot be seen, just as one cannot see grass growing." Which was an interesting assertion from a man who saw, among other clearly historic events, the Russian Revolution, the rise of the Bolsheviks, the Stalinist terror and World War II.

But let's work with Boris a little. No doubt he was correct in the sense that history sort of sneaks up on us. Day after day, stuff happens, and some of it is strange, some is unsettling, some is stirring, some is portentous. But we don't often know, in real time, whether these various happenings are adding up to anything meaningful enough to be called "history."

Yet there comes a day when you look out the window and notice that the lawn is extremely shaggy. You may not have seen the grass growing, but suddenly it's so high you can no longer find the dog's chew toys or the baseball glove you asked your kid 400 times to put away. And then it rains for three straight days and you realize there is no way your lawn mower can get through the sopping wet, jungle-thick morass without making a terrible mess of the mower, the lawn, your shoes . . .

Based on interviews with esteemed experts, the perusal of a stack of dense tomes, a plodding trip through thousands of pages of knotty articles in learned journals, plus the findings of assorted blue-ribbon federal commissions and weeks of squint-eyed reflection, I can report that this is precisely where America finds itself today.

We are up to our shins in the sloppy grass of history.

Maybe you have noticed. The past half-dozen years or so, strange things, unsettling things, stirring things, portentous things have been happening right and left. The decade of the 1990s danced in with such promise. No more Cold War. No more Evil Empire. The Persian Gulf War required a mere four days of land operations and seemed to spell the end of that gloomy, doubt-America malaise widely known as the "Vietnam syndrome." For a moment, it genuinely seemed that the most interesting question a president could face was, "Boxers or briefs?"

Then:

February 1998. A bloodthirsty zealot with a billionaire father declared war on America. Weird. From some cave or compound in Afghanistan, Osama bin Laden dispatched a fatwa to a London newspaper announcing the sacred duty of Muslims to kill Americans anywhere they could find us. Only a handful of us even noticed. But this strange event turned out to be truly historic. After all, how many rich fanatics have declared war on an entire country?

And how many, within six months, have managed to blow up two U.S. embassies?

Our elected leaders began making their own sort of history. On December 19, 1998, the designated speaker of the House, Louisiana congressman Bob Livingston, marched onto the floor of Congress, announced he was quitting on account of a sex scandal, and called on President Clinton to do likewise. That certainly felt new. The rich guy in Afghanistan was trying to have a war with us, but our government had painfully snagged on what we were calling "zipper problems." Yet this wasn't even the biggest story of the day, because Livingston's speech was a footnote to the fact that the House impeached a president for only the second time in U.S. history.

Then bin Laden's troops bombed, and nearly sank, a U.S. Navy destroyer.

Then came a deadlocked presidential election, the first in more than a century.

All this played out against a backdrop of dazzling new technologies and dizzying new wealth. Men and women barely out of college were making and losing fortunes that might have turned John D. Rockefeller's head -- and how? Strange, unsettling stuff: data harvesting, digital pet-food sales, cooking the books.

And then, bin Laden brought his war to the American mainland. Hitler couldn't get here. Brezhnev couldn't get here. But the radical Islamists managed to hit us harder than we had been hit at home since the Civil War.

Followed by Afghanistan and Iraq. Some people have begun using the phrase "World War IV." (No, you didn't miss one: WWIII is what used to be called the Cold War.)

Rogue states are developing nukes.

There's a plague decimating Africa.

The polar ice caps are melting.

It's no wonder our civic mood is grouchy. We are bombarded by banner headlines, caught in CAPS LOCK mode, deluged with dire declarations. Tom Wolfe dubbed the 1970s the Me Decade. We're living in the Yikes Years.

BACK IN THE SUNLIT ERA WHEN THE BERLIN WALL CAME DOWN, before all hell broke loose, a theorist named Francis Fukuyama published an influential essay announcing "The End of History." It was a highly philosophical piece having to do with the ideological triumph of democracy and free markets, but the catchy title took on a life of its own, coming to stand for the ascendancy of the United States and its ideals.

We're going to pay a visit to Fukuyama later in this article, and we'll hear what he now has to say about history. For the moment, though, just try to recall those days, when our leaders blithely wondered what to buy with our "peace dividend" and how best to manage the "Pax Americana."

Some people actually felt a twinge of regret at Fukuyama's coinage. No more history? What a drag! It was such an American response -- after all, history had been good to us, nationally speaking. History gathered up various scattered bands of religious outcasts, economic refugees and insatiable colonists; history molded these elements into a nation; history boosted that nation into the global driver's seat. Several years after Fukuyama wrote his essay, a French leader, Hubert Vedrine, decided that the word "superpower" wasn't enough for us anymore. America wasn't just "super," America was "hyper," as in hyperpuissance, hyperpower. It sounded like something out of a DC Comics futurama. The world had never seen our equal -- a single nation dominating the globe militarily, economically, culturally.

In those naive days, it seemed both a great relief and a slight shame to think that Americans might be done with an era of true significance and entering a time of uneventful sameness, that we might be embarking on a tranquil but meaningless period that would eventually be boiled down to a mere sentence or two in the history texts of our grandchildren and great-grandchildren. Were we destined to share the fate of the citizens of the Gilded Age, who apparently liked to argue over "free silver" while riding bicycles with absurdly large front wheels?

Now we see there was no need to worry.

One last belaboring of Pasternak: It's clear now that the end of the Cold War wasn't the end of grass; it was more like resodding the lawn. For a while there, nothing seemed to be growing. But new roots were going down, and once they took hold, the grass came back stronger and thicker than before.

So, what does this all point to? What does it mean? Years from now, when a virtual teacher downloads the history of our time into a microchip in our great-grandchild's brain, what will the data say?

"History?" President Bush answered with a shrug when Bob Woodward asked him how the future will view the Iraq war. "We don't know. We'll all be dead." I've become curious, though, about where the strange and unnerving events of recent years might be heading, and whether we can steer our course or must simply ride irresistible currents. I wanted a hint as to how this movie might end.

So while most Washington journalists were tracking each up and down of the presidential campaign, I tried to look past this single election, and even Bush's second term, toward the larger pattern of things. I began reading books with titles like The Future of Freedom and The Clash of Civilizations, magazines with names like Foreign Affairs and the National Interest and Technology Review. I began e-mailing provocative young scholars and sage older ones. I started paying visits to the offices of learned women and men who are paid to ponder where America is and where it is headed. I discovered that they tend to be concentrated along a stretch of Massachusetts Avenue NW, which I came to refer to as "Big Think Boulevard."

This is an intimidating world for a layperson to enter. The hushed hallways and book-lined offices of Big Think Boulevard are home to a priesthood that knows precisely the difference between "hegemony" and "empire," not to mention the difference between entente and detente.

I found that some of these thinkers fear we are living through the end of the Western alliance, while others believe America's power is already seeping away to China. I met thinkers who fret most about nuclear weapons in the hands of terrorists and others who prefer to worry about the speed at which our debtor nation is skidding toward fiscal crisis. You know things are scary when you find a wistful note of nostalgia for the relative stability of the Cold War creeping into the voices of level-headed people.

True, the brains of Big Think Boulevard have always shown a tendency to be worrywarts, except for when they are overly optimistic. Through the years, a visitor could have heard deep and earnest discussions along that street of the domino theory (by which the communists would conquer the world), the triumph of the German economy (which also did not happen) and the rise of superpower Japan (ditto). But just because predicting the future is difficult doesn't mean thinking about the future is pointless.

I found widespread agreement on at least two propositions:

First, that some very different sort of world is roaring up at us.

Second, that the history of our times will be the story of how we prepared for this different world -- which, so far, is mostly a story of how we have failed to prepare.

Yikes.

A FORMER GOVERNMENT OFFICIAL, THINK-TANK STAR AND NEWSPAPER COLUMNIST, Jessica Tuchman Mathews is now the president of a venerable outfit called the Carnegie Endowment for International Peace. The endowment occupies a handsome eight-story building in a prime spot on Big Think Boulevard -- a quietly elegant structure of glass and stone and wood, silent testimony to the power of Andrew Carnegie's millions multiplied by nearly a century of wise investment and compound interest. Human frailty being what it is, Carnegie's original goal of eliminating war has been scaled back over the years, and now the endowment is plenty busy just trying to keep wars from going nuclear.

I was hoping that Mathews might be able to summarize why being a hyperpower has turned out to be so unpleasant. Why, just a few years after the dawn of a new American epoch, it sort of feels like a fast-fading twilight.

"The past couple of years have shown us that the way we felt at the end of the Cold War -- the dominance we felt in terms of military power, economic power, so-called 'soft' cultural power -- was too facile," she began. America's power is "not at all as clear as it seemed just four years ago. Although we're spending approximately one-half of all the world's total military expenditures, and our power on that plane is supreme, it is not that usable against the enemies we now face."

She said this on a late-summer morning when Osama was still in his cave (or wherever he might be) and the low-tech insurgency in Iraq was metastasizing. So it was hard to argue with her assertion that certain foes are not cowed by the most awesome conventional military the world has ever seen. The United States has a fleet of nuclear submarines, every one of which packs enough megatons to decimate a nation. We have 12 aircraft carriers, every one of which totes more power than the entire air force of virtually any other country. We have stockpiles of laser-guided bombs and missiles that we can land on the proverbial dime. Yet we are flummoxed by beheadings -- a technology from the days of Salome and John the Baptist.

As it happens, this is a common problem for global powers: Conventional strength doesn't always succeed. The Romans had a similar experience with the Huns. Or a more recent example: In 1898, the British army won an overwhelming victory at Omdurman to regain control of Sudan and establish itself as the supreme fighting force on Earth. Within a year, the same army under the same general went off to fight the Boers in South Africa. At first, all went well: The British quickly seized the Boer capitals. Mission accomplished. But the opposing forces simply melted into the population, then launched a devastating guerrilla war that exposed the vulnerabilities of the superpower army.

Which sounds familiar.

Mathews continued: "On the economic side, we are very, very vulnerable." Strange: Wasn't it just a few years ago that the American economy was crushing its competitors like Godzilla mashing Toyotas? She cited two reasons to feel nervous. First, while the U.S. economy is easily the largest in the world, we're not even paying the bills of our own government -- not by a long shot. The federal deficit is more than $400 billion this year. And worse is sure to come when the baby boomers start retiring later this decade and Social Security and Medicare become massive drains. For the first time in our history, approximately half of our deficit spending is being financed by foreign nations. It can't bode well for a major power when its potential competitors hold the mortgage on its future.

The second economic weak spot Mathews sees is the explosive growth of the global labor market. With populous countries like China and India and Singapore and Malaysia rushing into the manufacturing age, "we're looking at a global labor surplus for an extended period, which is something new," Mathews said.

Let that sink in for a moment. An oversupply of a commodity means a declining price. A surplus of labor should mean lower wages, which means less saving and less spending, which means a sluggish economy, if not worse. Even the upside of cheap foreign labor -- the low prices we pay for clothes and gizmos -- often comes with a downside: a staggering trade deficit. At best, the coming years will be a nerve-racking race to convert those global workers into buyers of American exports, not just competitors for American jobs.

Brightening briefly, Mathews added: "We're still best in the world at adapting to rapidly changing circumstances. No other nation takes disruption in stride the way we do."

So the good news is, we're good at handling bad news.

Finally, as satisfying as it may be to many Americans, even U.N.-bashing may be beyond our power in the future. "I think it's clear there are not many really important issues we can tackle alone," Mathews said. Take the example currently occupying her attention -- the proliferation of nuclear technology in places such as North Korea, Iran, Pakistan, places that are hostile, unstable or both.

"A huge amount of work needs to be done on proliferation by a lot of countries working together," she said. "We can't accomplish what needs to be done by ourselves. And yet, what's the level of our political influence on other countries right now? When we were going into Iraq and the U.N. was resisting, I must have had 300 people say to me: 'Jessica, don't be silly. When push comes to shove, we'll get the votes.' But then it happened, and we couldn't get Mexico, for heaven's sake. Talk about a country that depends on us. Chile, which had a free-trade agreement on the line with us -- we couldn't get their vote.

"This is a long-winded way of saying that we are not nearly as dominant as we all thought we were just a few years ago."

I was surprised by how much agreement I found on this general idea among big thinkers, ranging from neoconservatives to multilateral peaceniks, from Republicans to Democrats to unaffiliated foreign intellectuals. They disagreed over nuances, but nearly all of them concurred that the rosy assumptions of the recent past must be completely reexamined. If the touchstone title of the 1990s was "The End of History," the title that speaks to the dawn of this decade might be Robert D. Kaplan's "The Coming Anarchy."

So where are we headed? Samuel P. Huntington of Harvard offered an early take on that question in his influential 1996 book, The Clash of Civilizations:

"In sum, overall the West will remain the most powerful civilization well into the early decades of the twenty-first century. . . . [But] the West's control of [key] resources peaked in the 1920s and has been declining irregularly but significantly. In the 2020s, a hundred years after that peak, the West will probably control about 24 percent of the world's territory (down from a peak of 49 percent), 10 percent of the total world population (down from 48 percent) . . . about 30 percent of the world's economic product (down from a peak of probably 70 percent), perhaps 25 percent of manufacturing output (down from a peak of 84 percent), and less than 10 percent of global military manpower (down from 45 percent).

"In 1919 Woodrow Wilson, Lloyd George, and Georges Clemenceau together virtually controlled the world. Sitting in Paris, they determined what countries would exist and which would not, what new countries would be created, what their boundaries would be and who would rule them, and how the Middle East and other parts of the world would be divided up among the victorious powers. . . . A hundred years later . . . the age of Western dominance will be over."

AND WHAT, YOU MIGHT ASK, WOULD BE SO BAD ABOUT THAT?

Back when happy students were building a papier-mache replica of the Statue of Liberty in Tiananmen Square, and Russian kids were waving American flags in Moscow, and the president of the United States and the chancellor of Germany were fast friends, American dominance felt like a rewarding and gratifying pursuit. Now, we read bestsellers like Blowback and The Sorrows of Empire, both by Asia expert Chalmers Johnson -- books in which the purported costs of our dominance are counted in a litany of miserable tolls. We're hated, Johnson informs us. We're resented. We're increasingly opposed by other nations. And a fair number of the world's people would like to kill as many of us as they possibly can. "In the long run," Johnson writes, "the people of the United States are neither militaristic enough nor rich enough to engage in the perpetual police actions, wars, and bailouts their government's hegemonic policies will require."

I once had the good fortune to visit Rome and found myself sitting on a perfect late-summer evening at a cafe on the vast Piazza Navona. Thousands of Romans, ineffably beautiful and thoroughly relaxed, were gliding happily back and forth across the plaza, hailing their many friends. The whole city, it seemed, had just returned from a month's vacation in the hills or by the sea. Shouted greetings and untroubled laughter were accompanied by the soothing music of water splashing in a huge fountain wrought by the master carver Bernini. My tummy was pleasantly full of prosciutto and figs and warm bread dipped in olive oil, and I found myself thinking that the best places to live in the whole world might be the capitals of former empires -- Athens, Amsterdam, London, Madrid, Vienna and right there in Rome -- where people enjoy all the cultural riches of having once dominated the world but are blissfully free of the burdens of leadership.

There's just one problem with that, said Niall Ferguson. "There isn't always a contender to take over" the job of leading the world; or sometimes there is a contender, but one who happens to be a genocidal maniac. "If the U.S. draws back from the imperial hubris of 2003 -- which I guess it already is doing; after all, it's hard to imagine America taking any new significant military actions for a while -- then the short-term and medium-term scenario is that large parts of the world will be left in a state of misrule under dictators, or in a state of no rule at all. That is rather a troubling prospect."

Ferguson is one of the hottest young stars in the foreign policy world, a thinker so big right now that he has hardly any fixed address. Just a few years ago, he was an unknown Oxford scholar working on a history of global fiscal policy (insert enormous yawn here). But it turned out that money really does make the world go around, or at least that it helps enormously to understand money if you want to understand history. Plus, Ferguson writes with flash and verve. His first book was a hit in brainy circles, and he followed it up with book after provocative book.

Now, at 40, he's a globe-trotting, multinational theorist of empire. It can take days of e-mail exchanges and transatlantic telephone tag just to track him down; when we finally did talk, he was taking a brief break from a conference in Lisbon. At least I think he was still in Lisbon.

While I was trying to find him, I read Ferguson's recent cover article in Foreign Policy magazine, a harrowing vision of a world without a dominant country -- a condition he called "apolarity" or "a global vacuum of power." We've seen such periods before, he observed: the so-called Dark Ages, for example, after the collapse of the Roman Empire, and, more recently, the demoralized 1920s, which gave rise to Hitler, Stalin and Mussolini in Europe and a resurgent Ku Klux Klan in the United States. We now see that the '20s also sowed the seeds of today's violent Islamicism, thanks to the dispirited intellectuals of the former Ottoman Empire, who began dreaming of a new order founded on strict Islamic law.

So: "Be careful what you wish for," Ferguson warned those who might like to see America pull back from world leadership. "Apolarity could turn out to mean an anarchic new Dark Age: an era of waning empires and religious fanaticism; of endemic plunder and pillage in the world's forgotten regions; of economic stagnation and civilization's retreat into a few fortified enclaves."

It's one thing to say, as most big thinkers do, that no nation has ever remained on top forever, and thus the United States, too, will someday see its period of dominance come to an end. The tricky part, as Ferguson's worries about a new dark age remind us, is figuring out a relatively peaceful path from hyperpower to former power.

There are plenty of theories about potential rivals to American power 20 or 50 or 100 years from now. At current levels of growth, China will blow past the United States as the world's biggest economy sometime in the next half-century, according to economists at Goldman Sachs. China's influence over East Asia is growing even faster than that. China's military is no match for ours today, but it has nuclear-tipped missiles and a big army, and the wealthier China becomes the more it can spend on guns, bombs, airplanes and warships, if it so chooses. Many theorists can paint a vivid picture of a not-so-distant world in which Asia is the center of the action, with China dominating the continent. One piece of that picture appeared in a recent article in the Massachusetts Institute of Technology's magazine Technology Review, which declared that the "world's hottest computer lab" is the one Microsoft has established in Beijing.

If Bill Gates is betting on China, perhaps we all should.

But even if things go smoothly for the Chinese, their nation is years away from rivaling the United States. And things are not likely to go smoothly. The coming years for China are precisely the phase in which other developing countries have experienced financial panics, civic unrest, economic meltdown and stagnation of trade.

Maybe Europe? Charles A. Kupchan of Georgetown University said the United States and Europe were bound to clash after their common enemy -- communism -- was conquered. Arguments over Iraq and the global warming treaty simply sped up a process already underway. The development of the European Union is moving much faster than anyone expected, Kupchan said, and the United States might soon find itself competing with a confederation of European countries. There may be a tipping point when the combined EU economy becomes larger than the U.S. economy, when the euro rivals the dollar as the global currency, and when America no longer sets the rules for global banking and finance.

Not everyone buys the idea of a bulked-up Europe, however, because Europe has problems of its own. European military power is mostly hollow, and some of Europe's leading economies are wheezing. The demographic picture is bleak: Native populations, especially in Western Europe, are aging and shrinking, which means fewer workers and more pensioners -- not exactly the muscular image of a rising superpower.

If it's true that no other power is ready -- or even close to being ready -- to step into the yoke of history, America's choice is to either hang in there or give up. Much of the world is not going to like either choice.

"Our real enemy may simply be . . . chaos in the world," said Walter Russell Mead, the Henry A. Kissinger senior fellow in U.S. foreign policy at the Council on Foreign Relations. Mead is another of the hot hands in the foreign policy business, harder to reach than a mid-list movie star. When I spoke to him by telephone, Iraq was boiling over and the United Nations was dithering about the genocide in Sudan. Yet Mead pronounced himself "optimistic" about the way history is unfolding -- as long as events aren't allowed to drift into madness.

"Where I worry," he said, "is that the social and economic changes underway are going to create chaos." Some countries, like the change-loving United States, will be able to hack it in a world of change. Others will not. The widening gap between the two is a zone of enormous danger, Mead believes.

"In many ways, I see Islamic terrorism as reflecting the changes of modernity in societies that may not be ready for them, or are divided by them," he said. "As the pace of change accelerates, and more and more people are affected, I worry we will see increasing resentment aimed at the country often seen as the source of these changes -- the United States."

Which brings us back to: Yikes.

I HALF-EXPECTED TO FIND FRANCIS FUKUYAMA SMOKING A PIPE AND PEERING AT A GLOBE WITH HIS BROW FURROWED. Or standing over a huge table covered with maps and encoded dispatches, his hands clasped behind him. Fukuyama is among the most widely acclaimed foreign policy theorists in the world. Even people who disagree with him routinely describe him as "brilliant."

But no, Fukuyama works in an ordinary professor's lodgings at 1619 Big Think Blvd. His is one of several small offices grouped around a bullpen at the Foreign Policy Institute of the Johns Hopkins University School of Advanced International Studies. (Eggheads simply call it SAIS -- pronounced "sice.") His standard-issue desk is heaped with the usual mounds of paper, and his nondescript bookshelves overflow with volumes that pool on the tables and spill to the floor. There is an appealing humility about the place; you have to scour the jumble with your eyes to spot The End of History and the Last Man, Fukuyama's book-length extension of his influential essay.

Contrary to the assumptions of people who only read the title, Fukuyama never claimed that historic events were going to stop happening after the fall of the Berlin Wall. His thesis was limited to a philosophical claim. He reminded readers that for almost 200 years, dating back to the German philosopher G.F. Hegel, many big thinkers -- notably Karl Marx -- viewed "history" as a sometimes violent struggle to determine the best way to structure society. History was believed to be headed toward a solution. Fukuyama argued that the end of the Cold War was "the end of history" because it left no plausible alternative to free markets and liberal democracy. End of argument, end of history.

Within that narrow definition, he may still be correct. The global clash of ideologies may well be over. Bin Laden isn't trying to create the future so much as he is trying to escape from it to the past, and a very distant, parochial past at that: medieval Arabia, and step on it. Still, Fukuyama acknowledged that this rarified use of the word "history" is less enlightening than it once seemed, because any notion of history that doesn't include the destruction of the World Trade Center is of dubious value.

The world has moved on, and so has Fukuyama's thinking. His recent cogitation has produced a seemingly simple but subtle realization that might explain a lot about why America's role in the world has become so difficult. America's enormous power, he noted, actually violates an axiom of the political philosophy we have been promoting for the past two centuries.

How so? As every civics class graduate knows, liberal democracy and free markets depend on "checks and balances" to rein in excess, to correct mistakes and to unleash creativity by bringing more ideas to the table. But now the unmatched military, economic and cultural power of the United States flouts the principle of checks and balances on a global scale. We don't expect monopolies to work well in economic markets. We don't expect dictatorships to survive free elections. Perhaps, he suggested, we should not be surprised to find that hyperpower has not ushered in a pastoral future.

"We believe that power without checks and balances is not safe -- even in the hands of well-meaning people. But today, we are an unchecked power," Fukuyama said. "After September 11, the world saw America's unchecked power in the military sphere. We reached out and overturned two regimes halfway around the world, essentially without help, and said to other countries, 'If you don't like it, you can just stuff it.' "

This rankles the rest of the world, which is naturally suspicious of unchecked power and, in fact, has a lot of practice in resisting it. Europe, for example, relied for generations on a "balance of power" strategy to stabilize the world. Whenever one government or axis became too strong, a fluid system of treaties would generate a competing alliance to level the field. This system wasn't pretty -- oceans of blood were shed in the age of Napoleon, in World War I and in World War II. Yet rulers preferred it to living with a single unchallenged power.

Then came a streamlined version of the same idea: the Cold War, in which two nuclear superpowers checked and balanced each other through the threat of mutual destruction.

American power "generates a big backlash," Fukuyama continued. While no nation is in a position to offset American military power, the world has other ways to thwart our intentions. Fukuyama envisions a difficult period in which the United States is stymied by "the rest of the world [deciding] not to cooperate with us on a lot of little things that, over time, really matter."

Iraq may be one of those "little" things.

Al Qaeda could turn into another.

The doozy, though, is nukes.

Nukes are the great X-factor, the cloud of uncertainty, floating over Big Think Boulevard. The future of Europe, the challenge of China -- such topics are good for the next conference in Lisbon or Aspen or New York. But bin Laden with a nuke: That's not a conference, it's a nightmare.

Everyone knows this, on some level. During the presidential campaign, both George W. Bush and John F. Kerry agreed that it was the No. 1 national security threat to the United States. But not everyone has really digested the problem, which is significantly more complicated than the nuclear threat during the Cold War. Having lived their entire lives in the shadow of The Bomb, many Americans prefer not to ponder the ways in which today's nuclear picture is more dangerous than ever.

During the Cold War, the world's security was built on a handful of interlocking truths that were dreadful to contemplate, but blessedly stable. First truth: It took a lot of money to develop a nuclear weapon. Second truth: It wasn't easy to deliver those weapons. You needed a long-range aircraft or intercontinental missile to put a nuke on a target without being vaporized yourself. Together, these facts created the third truth: We felt pretty sure that if we were going to be hit with a nuclear attack, we would know where it came from and whom to bomb back. The fact that nuclear bombs came with return addresses allowed us to deter nuclear attacks by threatening apocalyptic, glowing-molten-rubble retaliation.

Every brick of that deterrent edifice is now crumbling. Technology makes all things cheaper, including nukes. North Korea, a country where peasants forage for grass like goats, has nukes. Pakistan, where impoverished youths seeking an education must turn to schools preaching radical Islamism, has nukes. Some experts might call them "crude" nuclear bombs, but remember: Hiroshima and Nagasaki were hit by "crude" nuclear bombs.

Nor do you need a sophisticated jet or missile to deliver a bomb anymore. It turns out that suicidal zealots driving panel trucks are very cheap, very precise guidance systems. Who knew the world contained so many of them?

Cheap bombs plus cheap guidance systems mean that a nuke could go off in Washington tomorrow, and we might never learn for sure where it came from. Nor, as we've seen in our hunt for bin Laden, would we necessarily know where to find the culprits. Nor, with an enemy that fetishizes death, could we be sure the culprits would fear retaliation. For all these reasons, what worked in the Cold War won't work anymore.

The bomb will determine whether America's current fight against radical Islam represents a bump in the road of history or, as the venerable neoconservative Norman Podhoretz argued recently in Commentary magazine, "World War IV." Minus the bomb, in Fukuyama's words, "Islamism is much weaker than fascism or communism were. Its appeal is limited to Arab and Muslim countries. It has come to power in just three places -- Afghanistan, Iran and Saudi Arabia -- and all three are a mess. It's a protest movement of angry, marginalized people who haven't been able to integrate into the modern world."

But . . .

"If they take over Pakistan, say, then they have 60 nukes. And all of a sudden you have to take them pretty seriously." In other words, one of the biggest historical questions the United States now faces is impossible to answer. Ten years from now, will al Qaeda be a fading threat, or will downtown Washington be a pile of radioactive debris?

Before leaving his office, I asked the professor to think back to the End of History days. He smiled ruefully. "It's definitely less pleasant today," he said. "We've got some real problems now."

"YOU WANT TO HAVE SOME SOBERING THOUGHTS?" Walter Russell Mead had asked during our conversation about world chaos.

Before I could answer no, he posed a mental experiment: "Ask yourself, what's the worst that terrorists could do to us in 1901?"

History gives an approximate answer: In 1910, radical labor leaders bombed the headquarters of the Los Angeles Times, whose publisher was a staunch anti-unionist. The building collapsed, killing about two dozen people.

"Now, what's the worst they could do in 2001?"

That's easy. They did it on 9/11.

"Okay, what's the worst they could do on September 11, 2101?"

Ugh.

Advances in science and technology -- material progress in general -- are not just a force for good. The bad guys also benefit. "It's not just nuclear you have to worry about," Mead said. "It's biological, too." The same genetic discoveries that promise new cures will, no doubt, reveal new ways to kill as well. "See, technology strengthens the forces of order and law, but it also strengthens the forces of anarchy and terror. Technology is not the automatic problem solver. The notion of liberal democracy and capitalism leading to the peaceful, quiet end of history underestimates the dynamism that capitalism and liberalism actually contain. In that sense, it's Pogo who has the last word: We have met the enemy and he's us . . . It's not clear that our ability to cope with change is growing as fast as the pace of change itself."

We might be getting to the nub of the matter here.

What were the 1990s all about in America if not a nation intoxicated by the perfume of change and drunk on the promise of technology? We chose a free-associating futurist, Newt Gingrich, to run Congress and a president who painted word pictures of a sunny bridge to the 21st century. Business leaders chanted the mantra "change or die," while the newsstands were full of magazines offering to teach us how to make change our friend. There was a giddiness to it all. In the future, people would live forever, and the Dow would never go down. Only fuddy-duddies and Luddites and cranks saw any drawbacks to the future.

But other people, including some cranks in caves, were taking a very different view of change and of the future. They were asking which changes they could prevent, which ones they could reverse, and which changes they could turn into weapons against the future, judo-style. They failed to rivet our attention because we didn't think they merited attention; they weren't with the program. But guess what? Because of those people, the "bleeding edge" of change that hip people enjoyed talking about 10 years ago has turned out to involve a lot of actual bleeding.

The unsettling signs and portents of the late 1990s now strike us as the burps and tremors of a volcano that was about to blow. The decadent trivia of politics in those years -- the sex scandals, the debates over hairdos, the millionaires and billionaires seeking to buy themselves high offices, the extreme niche-marketing of issues that once led President Clinton to offer a White House initiative on child safety seats -- all these combine into a sort of barometer of our national blindness, and, as such, were truly historic -- because they represent a generalized failure of the futuristic hyperpower to see even the slightest distance into the actual future.

Time and money wasted on such trivia could have been used instead to plan for the menaces sure to crop up in the wreckage of the Cold War. Those years could have been used to begin creating the new international institutions, treaties and alliances that would allow the United States to lead and stabilize the world without violating the tested principle of checks and balances. They might have been used to craft a new strategy for avoiding nuclear war that would have as much weight and urgency behind it as the old strategy had.

To be fair, American leaders have tried, in various ways, to engage the future. President Clinton pulled Bosnia back from the brink of chaos. The first President Bush built a coalition to enforce the U.N. mandate to liberate Kuwait. More recently, George W. Bush offered a doctrine of preemptive action to replace the now-inadequate Cold War deterrence theory.

But none of these efforts have so far proved compelling enough to mark a clear path forward.

Along Big Think Boulevard, people have their doubts whether America's leaders, from either party, will be able to brace the public for what promises to be a long and often unpleasant engagement with our clouded future. There is, after all, a strong and deep vein of isolationism bred in the American character. If one day in the not-so-far-off tomorrow we find that we must choose, for example, between paying the costs of global leadership and paying the pensions of our burgeoning retiree class, isn't it likely that we will pull back -- whether or not there is an acceptable nation ready to step into the void?

Again and again, I heard big thinkers draw a contrast between this era and another hugely historic period: the immediate aftermath of World War II. They noted the alacrity with which the Allies, seasoned by economic depression and catastrophic war, pivoted to comprehend and face the future. The war ended in 1945. The following year, Winston Churchill delivered his "Iron Curtain" speech warning of Soviet expansionism. The next year, 1947, George Kennan laid out the strategy of "containment" that was quickly embraced by a bipartisan consensus of Western leaders, and the massively expensive Marshall Plan was launched. By 1948, President Harry Truman had established the doctrine that would guide Western foreign policy through Democratic and Republican administrations for the next 40-plus years. And in 1949 NATO was created to implement that policy.

Four years to reinvent the world.

I got a lot of shrugs and groans when I asked if anyone perceives a similar vision and unity of purpose today. Mead chose to answer by quoting Churchill. "He said, You can always count on the Americans to do the right thing -- after exhausting all the other possibilities."

THERE CAME A POINT IN THIS INVESTIGATION WHEN I NEEDED TO HEAR THE BRIGHT SIDE, if there was one, in meatier form than the empty campaign-season exhortations that were leading the morning newspapers. So I sought out Joshua Muravchik, whose specialty is studying the spread of democracy and freedom around the world. His little office is located at the American Enterprise Institute, one of Washington's oldest and most influential think tanks, where Muravchik is a resident scholar. AEI occupies several floors of a nondescript Washington high-rise just off Big Think Boulevard -- a gray building on a gray street under gray skies the morning I visited.

Muravchik is a neoconservative of the purest type, meaning that he started out some 40 years ago as a hawkish Democrat and today is a hawkish Republican. He is different from the classic conservatives of the GOP -- the "old-o-cons," as some call themselves. Neocons are more likely to eagerly seek out opportunities to change the world; old-o-cons are more likely to advise caution, on the theory that the world's biggest problem, namely human nature, is stubbornly resistant to change.

Neocons in the Bush administration got much of the credit -- or blame, take your pick -- for the decision to invade Iraq. So when you meet a thinker of this sort, you might expect a fire-breather. Muravchik, however, turned out to be a genial fellow of winning humility. "You're asking big questions," he said right off the bat. "I'll probably get myself into trouble here."

Then in he dove. Sure, he said, we're looking at a tricky and scary patch of history ahead. And yes, eventually, history will erode America's dominance. "Obviously, our time on top won't last forever. Everything comes to an end. But whether it lasts another 50 years or 500 years, I can't say. My guess is, this has a long way yet to go."

He believes this because he sees a strong historical tide flowing in our direction. "For how many millennia was the world run by kings and warlords?" Muravchik asked. "And then the first elected democracy springs to life in 1776. It was a very imperfect democracy, a slave democracy, but still it contained this idea that people would elect a government temporarily and then a few years later elect a new one.

"How many people participated? A small group: The entire political polity of the early United States was what -- a million people? From then to now is a blink of an eye in historical terms. But today, of the 192 countries in the world . . . 120 have elected governments." Granted, many of those are far from true democracies, but 89 qualify as "free" nations, Muravchik said, in which citizens elect their leaders and enjoy human rights guaranteed by the rule of law.

"Not all of that was accomplished by the United States," he concluded, "but it began with the American model." This "remarkable triumph of American ideas" leaves him in the "long-run view . . . optimistic."

The neocon had the same worry as the rest of the Big Think gang: that Americans, bloodied by Iraq, scorned by former allies, ill-served by squabbling leaders, will elect to pull back from a menacing world. "People could say: 'This is crazy! Bush bit off more than we could chew. We have a good life here . . . let's just batten down the hatches,' " Muravchik said.

My mind drifted back to that evening in Rome, and my vision of the happy lives of the formerly dominant.

"The withdrawal of American power would stir fears all over the world," Muravchik went on, puncturing my reverie. "It would create temptations, because the people who rule nations are very ambitious men. Some would act on those ambitions. The result would be lots of bloodshed, and at some point, we would be dragged back in."

At that point, history suggests, things would look even worse than they do now.

I came away from Big Think Boulevard having reached a few conclusions, for what they are worth.

The end of history was a dream, lovely and fleeting.

While we slumbered, the grass grew very tall.

Now we have to cut it, and if there is an easy way to accomplish the job, no one knows what it is.

And last: The very hope that such work would ever become easy -- the eternal but vain wish that history will level off into a broad and tranquil, sunlit meadow -- is a big part of the reason we're in such trouble. The most enticing dreams can be the most dangerous.

David Von Drehle is a Magazine staff writer. He will be fielding questions and comments about this article Monday at 1 p.m. at washingtonpost.com/liveonline.