It is almost as hard for friends to meet, As for the morning and evening stars. Tonight then is a rare event.
But meet they did for the Olympic Games as Beijing kept its date with history (that night) on August 8, 2008. The lines by Du Fu, composed centuries ago, are truer than ever in this materialistic world where it has become so difficult for true friends to meet.
Tonight, friends will gather at the National Stadium (athletes, sport officials and journalists) and those across this wide expanse of planet we call our home will get a second glimpse of what China, its people, history and culture are all about.
Some medals are still to be won and the celebrations are still on. And no matter what Spanish tenor Placido Domingo and Chinese soprano Song Zuying sing tonight, the words will mean Amigos para siempre or We'll be one.
But the parting has to wait. Not so soon. China had to wait more than a century since first expressing its desire to host the world Games. It had to prepare for seven long years for 17 days of joy, with its 1.3 billion people rising as one to turn that dream into sweet reality. So when the dark cloud ultimately shrouds Beijing tonight it will not be without the proverbial silver lining.
There will always be a London 2012 after a Beijing 2008 - that is what the slogan One World, One Dream is all about. That is what China means by peace and harmony.
Tales of heroism, valor and strength, of failures and heartbreaks, of overcoming odds are what make the Olympics what it is. For every Michael Phelps and Usain Bolt there is a Natalie du Toit and Natalia Partyka. Liu Xiang can take heart, for the Games is not about medals alone.
It's also about the Matthew Emmonses, who throw his gold medal at successive Games, and still get a warm hug from their dear ones. It's about the Russian and Georgian shooters hugging each other even as their countries are drawn into a conflict.
And it's about Bolt again - for his $50,000 donation for the Sichuan earthquake victims. Not for nothing is he a great sports ambassador.
And of course, it's about Oksana Chusovitina, who at 33 competed with the world's top gymnasts and still won the silver to support her son in his fight against leukemia.
Beijing's hottest days are over. The much-anticipated coming-out party for the world's most populous country began with a dazzling display of its culture and message of global harmony. This evening, it will end with genuine revelry after all the incredible dramas on and off the fields, leaving a legacy for China and the world.
"We are dedicated to creating a happy atmosphere at the closing ceremony," Zhang Yimou, chief director of the opening and closing ceremonies, has said. "The message is to say goodbye, and to promise to meet again in four years."
London, the Games host, will get eight minutes at tonight's show when the Olympic torch will be formally handed over to the London mayor.
There will be David Beckham, expected to arrive atop a red double-decker bus and kick a football into the crowd. There will be former Led Zeppelin guitarist Jimmy Page performing a duet with pop star Leona Lewis. But their message will be one.
As Greek Foreign Minister and former Athens mayor Dora Bakoyannis said earlier, the message of the "Olympic Games is one, and has withstood the test of time: Excellence in sport is all about hard work, determination and faith ... these very same qualities can today serve as a vehicle for social change and development of humankind."
That is what China has dreamt of, and that what it wants Beijing 2008's legacy to be.
