The state visit to Washington of the Chinese leader, Hu Jintao, is a unique diplomatic occasion. For the first time, many Americans see in a foreign leader a man who embodies a future where America is no longer on top.
On the airwaves you can almost hear the sucking sound as the tide of history sweeps wealth and power from the US towards China. For some analysts the moment is equivalent to the arrival of President Woodrow Wilson in Europe in 1919, of a new global authority taking over from the fading colonial powers.
Of course America has faced rivals and insecurity in the past. The old Soviet Union from time to time appeared to outgun the US, sparking a wave of defeatist angst. In the 1980s, as Japan bought up bits of Manhattan and Hollywood, it seemed as if Tokyo would become the dominant economic power. We know what happened to that scare story.
In China, however, the US faces a country with an unstoppable economic momentum. It has a resurgent military, which clearly wants to drive out the US navy from the seas of East Asia. It has a non-democratic but efficient political set-up that defies all the wisdom of the West. Most important, China feels confident enough to reject the advice, much of it self-serving, from US politicians and bankers on the need to open up its political system and revalue its currency.
There is one thing that both sides can agree on: the future of the world is in the hands of the Hu-Obama couple. Hillary Clinton, the US secretary of state, has said that their relationship will in many ways "determine the peace, stability and prosperity of the 21st century". Mr Hu says the two countries carry the world's "important responsibilities".
The rhetoric set the stage for an epic duel in Washington; the Wagnerian mood music was playing. Yet something has been missing: Mr Hu fails spectacularly to live up to his billing as the warrior who will fell America.
In an attempt to raise the drama of the occasion, Senator Harry Reid, the senate majority leader, called Mr Hu a "dictator". But he immediately rowed back, realising this was a ludicrous thing to say about a low-key leader who got to the top not through a triumph of the will but thanks to a complex bureaucratic process. In some ways the US would prefer a real dictator, for then they would know exactly whom they were dealing with.
One of the defining moments in the US-Chinese relationship came in 1979 when Deng Xiaoping, the twice-purged communist who set China on the course to a market economy, donned a cowboy hat at a Houston rodeo. The image was memorable not just for the contrast between the diminutive Deng and the 10-gallon hat: it showed he was a man America could do business with, a real politician with a sense of occasion. Deng was no more democratically elected that Mr Hu, but he was an asset to the US who could drag his country into a new age.
For all the hype about the summit, there is a feeling in Washington that Mr Hu is at best a transient figure and that China has become too complex a state over the past 30 years for one man ever to call the shots.
The doubts about Mr Hu were crystallised when Robert Gates, the US defence secretary, visited Beijing last week and was shocked to find that the Chinese military had chosen his visit to show off its first stealth fighter. This was a clear slap in the face to Mr Gates. Even more surprising was that Mr Hu, when pushed about this, appeared not to know about the test flight.
This would be worrying in any country, but especially so in a country run by a nominally communist party. Such parties have always made a fetish of keeping the military under strict political control.
There has been much debate in Washington over whether Mr Hu is duplicitous or just the weakest Chinese leader of communist times. His claim not to have heard a question about China's human rights record at his news conference only reinforced his reputation as a man who does not project power or authority.
It is clear that the leader has to negotiate among powerful groups, such as the military and the state corporations that now have economic interests around the world. The complexity of Chinese society is hidden behind the residual monopolies of the communist party, especially the control of the media and the appointment of personnel. Nevertheless, the concept of "paramount leader" seems outdated.
Mr Hu is also on his way out. His putative successor, Xi Jinping, is expected to be anointed next year, in what marks a generational change. To judge by his remarks on a recent visit to Mexico, where he lambasted "a few foreigners with full bellies [presumably Americans] who have nothing better to do than try to point fingers at our country", he should make more of an impression than the incumbent. Or perhaps not.
The US should not be surprised that one man cannot hold China in his grasp any longer. Even the US president cannot do that with his own country in matters of the Middle East. Mr Obama, for instance, appears far less powerful in Washington than American's unruly client, the Israeli prime minister, Benjamin Netanyahu.
Nor is Mr Obama a fixture. Already John Bolton, the blunderbuss of the George W Bush White House, is warning the Chinese to prepare for the post-Obama era. "There could be a different president two years hence, ready to reverse his agenda of international passivity and decline," Mr Bolton wrote in The Financial Times.
This is not an age where summit meetings can change the course of history. The world is more complex and increasingly so. China is not going to supplant the US in the way that Washington bestrode the globe after the collapse of the USSR. And despite the pressure in China from nationalists for it to project influence more aggressively, the global balance of power is not going to be the subject of any quick fixes. Rather it will be a long and difficult negotiation both between Washington and Beijing, and just as importantly, within China itself.