The world seemed reborn on November 9, 1989, the day the Berlin Wall came tumbling down, but the promise held by that euphoric event transformed again with the second epochal date of a generation - September 11, 2001. As Europe and the United States prepare to mark the 15th anniversary of the end of the Cold War, political leaders are looking back at the chain reactions triggered by that unparalleled moment of joy.
They are also examining the new fault lines exposed by the dissolution of a bipolar world, with the West on one side and the Soviet bloc on the other, into a globe with a single superpower.
And they are tracing the new common ground between former foes and the fresh divisions between long-time allies laid bare by the attacks by Islamic extremists on New York and Washington.
"November 9, 1989 and September 11, 2001 changed Europe, transatlantic relations and, ultimately, the world as a whole," the German government's co-ordinator for transatlantic relations, Karsten Voigt, said in a recent speech.
Voigt noted that the sense of common purpose in the West in the years after the Wall's fall fractured with the US-led invasion of Iraq.
"The experience of September 11 led to a new view of the world, first in the US and then in Europe. The altered awareness in the US following September 11 was underestimated by many Europeans at first."
German Foreign Minister Joschka Fischer acknowledged that the nature of war had changed since the Iron Curtain lifted, and said the September 11 assault had only accelerated that transition.
"Conflicts now are often linked to the erosion of state authority," Fischer said at a Berlin conference entitled "Beyond Cold Peace" last week.
"Failed states are most devastating for their citizens. There have been enough tragic examples," he said, with an eye to both the Balkans wars as Yugoslavia fell part as well as Afghanistan under the Taleban as it played host to Osama bin Laden's al Qaeda network.
Germany's ambassador to Britain, Thomas Matussek, recently lamented that many in the West had taken far too long to realise that the post-Wall world had become anything but simpler.
"If there was any need at all to remind us that the emergence of an order of peace in Europe would not usher in the 'End of History' in which we could all happily enjoy a tranquil 'peace dividend', September 11 certainly brought home that message very forcefully," he said in a speech in London.
But he said that at least for an instant in history, alliances formed across ideological and regional lines against a new menace to security and stability.
"If one compares the sense of global unity right after September 11th with the fundamental divisions of the world community of the Cold War, the contrast could not be any starker. In the aftermath of 9/11 the old notions of the West and the East practically lost their decades-old significance," he said.
Meanwhile leading US officials have used the symbolism of Cold War Europe to describe the situation in much of the Muslim world, and said US action to topple Iraqi leader Saddam Hussein was a first step in spreading freedom, just as it galloped through Europe after 1989.
"The fall of the Berlin Wall and the fall of the World Trade Center were the bookends of a long transition period," US National Security Adviser Condoleezza Rice said in a September 2002 speech outlining the notion of "preventative war," six months before the Iraq invasion.
"After 9/11, there is no longer any doubt that today America faces an existential threat to our security - a threat as great as any we faced during the Civil War, the so-called Good War, or the Cold War."
In a speech last autumn, US Democratic Senator Joe Lieberman, a supporter of the Iraq war, compared the repression of Muslim dictatorships to the Soviet threat and said the West had a responsibility to face it down.
"Half a century ago, ideological extremists drew a political iron curtain across Europe.
"Today, the fanatical forces of jihad are trying to build a 'theological iron curtain' to divide the Muslim world from the rest of the globe."
Matussek said that this shift in perception of the threats and opportunities facing the West was perhaps only natural.
"Given the tectonic shifts in the global order we have seen in the last 15 years or so, it would be miraculous if the transatlantic relationship remained a static one," he said.