Few moments in history are as clear and as defining as that of 9.06 a.m. on Tuesday, the 11th of September, 2001, when a jet packed with terrified passengers, a suicidal pilot at the controls, sliced straight into the South Tower of the World Trade Center in New York. The sleek dark blade entered at an angle and seemed to disappear, as if swallowed by the building in a single, effortless gulp. And then came the explosion, as tons of jet fuel, enough to take the plane across America, engulfed the top of the shuddering giant. The scene was captured live on television, across the world. We knew it was a terrorist attack. Because 18 minutes earlier another plane had flown straight into the building’s twin, the North Tower. The first crash, to shocked minds, could have been an accident – inexplicable though this would be in broad daylight in an era of infallible navigational security. The second was the end of the world as we knew it. One day, perhaps we will remember this day not for the surprise and horror over the death of untold thousands in the collapsed buildings, or the despair of those calling for help from the windows before choosing to plunge hundreds of meters to their deaths, or the terror of the 250-odd captives on the four planes that were commandeered to become suicidal missiles. We will remember it as the day in which the bonds of a social contract that kept the world functioning suddenly came loose. It was a moment in which the terrorist acts themselves were secondary to the realization that, with persistence and planning, anyone in our age of lightning-fast communications and mass transportation could empower ancient grievances to take lives on an unprecedented scale. The balance shifted. If a small group could destroy the World Trade Center and crash a plane into the Pentagon, it will surely use nuclear and biological weapons against any target when it gets them. But, as Tuesday showed, it does not need them. In a way, what will matter more than the attacks themselves and their victims will be the fact that they took place at all. A small group did what a superpower would not dare to do. Since the end of the Cold War we had become used to what we called a world with one superpower. Then, with the Internet and ever greater technology, we got the super-empowered individuals. And now the balance is even. No empire has ever been more powerful than the United States, nor more vulnerable. Like every empire, its strengths and weaknesses are tied inextricably to its era and to the application of the technology it has developed or acquired. Every nation or amalgamation of nations that grasps the opportunities of the age will conquer, from Classical Athens’s naval tactics, gaining the city state an empire by default, to Philip of Macedon and his son Alexander developing military tactics to exploit the invention of the long spear and broad sword and then slicing through the mighty Persian Empire, to the Romans’ organization and roads, to the American incentives of personal wealth and fame for some of the world’s best and brightest minds to develop technologies that gave them the edge over their equally bright counterparts in the Soviet Union who had to labor under a crippling, centralized system that rapidly ran out of money. Constantinople’s final fall was hastened by the Turkish sultan’s purchase of cannon that the exhausted, hemorrhaging 1100-year Byzantine Empire could not afford. But every empire has had a very strong boundary, both physical and ethnic. Neighboring peoples were defeated and destroyed or were absorbed. Garrisons in hostile territory might be demolished, revolts might be crushed, incursions might be fought off, but a crippling attack on the heart of the empire by a band of zealots would never have been feasible – nor significant. The United States, however, has been an empire without an empire. Aside from isolated garrisons across the world it holds no outside territory. It’s conquests are mostly those of the mind, of the imagination, where it dominates. It has presented a dream for other nations and a pole for their ambitions and their anger. It has invoked the wrath of the weaker, more for what it does not do – as when it is seen favoring one nation above another – than for the highhandedness that is customary for empires. The United States is built on a foundation of sharing. For good and ill. It has sold its technology to the world (at ever lower prices); it has forced markets to open, and in doing so has given many more people greater freedom both to succeed and to fail. And it has tried to shape the world in its own image. Although putting its own interests first – as every country must – America has tried to make the world more like America. It has also shared its image with the world. What the American media show of the rest of the world is what will draw the world’s attention. What happens in America is known all over the world, and no more so than in this time of pain, horror and, only secondarily, humiliation of the terror attacks. Whatever could happen elsewhere has now happened in America. For the first time in their modern history, the American people have felt the terror that war and uncertainty have rained down on practically every other nation at some point. And the unbearable irony is that it was the open, casual way in which Americans dealt with their domestic airport security while pillorying others for theirs that opened the gates of hell. And it was American planes, those great symbols of the global citizen’s ability to break free from the bonds of time and distance, that wreaked such incredible destruction within minutes. The terrorists at the controls had been taught to fly at American flight schools. The inconceivable happened in fast forward and is now permanently engraved in history, in a billion slow-motion replays in the deepest recesses of our memory. The two buildings that were the world’s tallest when they went up 30 years ago, and were built to withstand earthquakes and even the crash of a jumbo jet, tumbled down into a humble mess of steel and fire and dust. The ashes of thousands of people rose with the dust of the fallen towers into a plume over the globe and were visible from space. Crematoria in the sun. Where blind skyscrapers use their full height to proclaim the strength of Collective Man as the poet W.H. Auden wrote, sitting in a dive on New York’s 52nd Street at the start of World War II, in another September 30 years before the Twins were built. No amount of vengeance can erase the moment. The war was won the moment the first blow of battle fell. That is the nature of terrorism. That is the world today: Where those who feel that evil is done to them can do evil in return. They need no armies and they need no battalions. They just need to choose. What will tomorrow bring? Old pain and new arrangements. The post-World War II era is over. The United Nations, NATO and other alliances will feel their way toward a new balance of interests. Irrespective of what retaliation the United States will carry out, it will quickly withdraw into a kind of isolation, nurturing only the ties with countries that are useful to it and show that they are prepared to stand wholeheartedly by its side. It will press hard against terrorism of every form, with little time or patience for diplomacy. It may also be less liberal in sharing its inventions or its civil liberties. This could imply a radical rearrangement of the way the global economy functions. But this shock and the signs of a recession may be precisely what will raise these new borders. In short, America might begin to function as a true empire, without foreign territory but with allies toeing the line. A long time ago, when the Athenians returned home after beating the Persian invaders, they debated leaving the smoldering ruins of the wooden temples on the Acropolis, in order that the world would see for all time what the barbarians had done. Instead, they built the Parthenon. Courage, friends.