On Christmas day 20 years ago, news reports around the world announced the resignation of Mikhail Gorbachev, the last president of the Soviet Union.
With his departure, the USSR dissolved, and the first socialist state was consigned to the dustbin of history.
It was the end of an ideology, and an empire. (Watch the Soviet flag lowered for the last time.)
Andrey Grachev retired from politics the day after Mikhail Gorbachev did. His final assignment, as Gorbachev's press secretary, was to tell the international press corps that the Soviet Union was no more.
"Somebody compared my role in those days to a character in the medieval theater, who's switching off the light once the play is over," Grachev recalled.
There are lots of theories for the Soviet Union's sudden demise. But how does an insider like Andrey Grachev explain it?
"I think it died from inside," he said, and not as a result of external pressures or enemies.
Grachev said he thinks the times of greatest conflict, the Second World War and the Cold War, actually strengthened the Soviet state.
"The most dangerous phases for the regime were the periods of detente, of peaceful co-existence, the periods when the external threat could not be used as the justification for the persecution of dissidents and the internal opposition," Grachev said.
The Soviet Union's chief vulnerability, he added, was a structural one; it was a huge, multi-ethnic empire.
"The great historic paradox of the Bolshevik Revolution was that when most world empires were breaking up, it was this new project, the communist project, with its international message, which amazingly helped the former Russian Empire to survive in the form of a new, rejuvenated, revolutionary state. A common motherland for all the nations, with most of the oppressed nations participating in the struggle against the Czarist regime."
The Bolsheviks were the first Marxist party ever to seize state power. They promised to build a worker's paradise, and a common motherland for all of Russia's national and ethnic minorities. But by the l930s, the dictatorship of the proletariat had turned into the dictatorship of Josef Stalin, and the Soviet state came to resemble the vast, imperial system it had overthrown.
"It was a very rigid structure, which could be kept together mostly by force and coercion," Grachev said.
It also barricaded itself and its citizens from the rest of the world.
Even so, the Soviet regime had some staggering achievements. It transformed Russia from a mostly peasant society to a modern industrial state; it vanquished Hitler's armies during World War II; and it became a world leader in science.
On April 14, l961, Soviet cosmonaut Yury Gagarin became the first man to orbit the earth. There was world news coverage of Gagarin being greeted by Soviet leader Nikita Krushchev.
Four years earlier, the Soviets had launched Sputnik, the world's first satellite. It was the height of the Cold War, and the beginning of the space race.
Soviet leaders poured money into space and military programs. By the early l980s, the Soviet Union had more tanks, troops and nuclear weapons than any other nation on earth.
"The Soviet Union was competitive in one sector, which was this military economy," Grachev said, "but at the price of destroying the rest of the economy and the standard of living of most of the population."
When Mikhail Gorbachev became General Secretary of the Communist Party in l985, the Soviet economy was in a state of near collapse.
"He realized something had to be done. We can no longer live like this' was a common line," said Masha Lipman, a political analyst at the Carnegie Endowment in Moscow.
"A common word that people used to describe the period of late stagnation was 'marasmus.' And it was merazum in Russian. Because the system was in a state of degradation, and everybody saw it." Lipman said.
It was an economy of shortages; Soviet citizens spent hours standing in line for basic necessities. The gap between the official communist rhetoric and reality was a mile wide.
"The ideology that had been part and parcel of the system early on, after all it was an ideological empire, this ideology had grown hollow, and become hypocritical."
Gorbachev tried to rescue the system by allowing private enterprise and ending the communist party's monopoly on power. He also vowed to slash military spending, and end the Cold War.
But then in June of l987, President Ronald Reagan stood in front of Berlin's Brandenburg Gate, and dared him to do even more. He famously urged Gorbachev to "Tear down this wall."
Two years later, Gorbachev allowed that to happen.
In an interview on Russian television earlier this year, Gorbachev said he knew he was doing the right thing by letting the Eastern Europe satellites go. But it was still hard.
"And it was so moving because he admitted it," according to political analyst Masha Lipman. "He as a person who inherited this huge empire felt that there was something very wrong about them suddenly setting free of us. I mean we are the boss, we are the master, we are at the center of this universe. But he let them go."
The fall of the Berlin Wall sent shock waves throughout the non-Russian republics on the Soviet Union's periphery.
Andrey Grachev said that during his last months in power, Gorbachev was trying to transform the USSR into a voluntary federation.
But once it became clear he would not use force – or fear – to keep the USSR together, the whole structure imploded.
"After all one of the elements of keeping together this huge historic and geographic reality was fear," according to Andrey Grachev.
But the USSR wasn't just destroyed by the forces of nationalism. The collapse of communism unleashed something even more powerful: greed and lawlessness.
Perhaps that's what Gorbachev was warning about in his farewell address to the nation on Christmas Day of l991, when he said that Soviet society had acquired political and spiritual freedom, but that it had yet to come to grips with that achievement.
"People in this country are ceasing to be citizens of a great power," Gorbachev added.
In the end, the collapse of the Soviet Union turned out to be a great misfortune for most of the population, said Boris Kapustin, a visiting professor of ethics and politics at Yale University
"We are increasingly becoming a third world in any respect," he said, citing declines in science, education and health. "This is not just an economic disaster; it's a cultural disaster as well."
Valery Solovei, a professor of history at Moscow State Institute for International Relations, thinks this might explain the current protests against the Putin regime.
"The Russians hate the authorities," Solovei said.
He said he doesn't think most Russians want a return to Soviet socialism, but they'd like to have a functioning state.
"They want to have normal health care, which they're willing to pay for. But even for money, they can't receive anything. Even very rich people can't receive normal health care or education for their children," he said. "It means that the social system doesn't work now, and the authorities don't function either. The Russians see it and this is a problem."
In other words, it's not over yet.
Twenty years later, the Soviet Union is still collapsing.