Only yesterday, it seems, decades of oppression disappeared overnight. On Nov. 9, 1989, the Berlin Wall, the symbol of the most grotesque human tyranny ever to plague the globe, was opened. Free, free at last, shouted residents of half a continent.

So dramatic was this revolution that it is easy today to forget that communism ever existed or at least what it really meant. Decades of totalitarianism impoverished people not only economically but spiritually.

Communism’s body count dwarfs that of fascism and Nazism. The Black Book of Communism, newly published by Harvard University Press, estimates the slaughter at more than 100 million. And the killings continue in such Communist hell-holes as North Korea.

Today the former Communist states range from robustly democratic to unpleasantly authoritarian. However, all are light years beyond what former U.S. President Ronald Reagan so accurately termed the Evil Empire.

What seems inevitable today was not obviously so in 1989. As the year dawned, the Soviet bloc was stirring.

Still, liberty had always seemed to end up still born in the Soviet empire. The 1968 Prague Spring, 1956 Hungarian Revolution, and 1953 East German demonstrations had all been summarily crushed.

Not in 1989, however.

Hungary led the way. The man who betrayed his colleagues in 1956, Janos Kadar, had been deposed the previous year. The murdered revolutionary leaders were reburied. The Communist Party was dissolved.

The Polish Communist regime was foolish enough to actually hold free elections. Its candidates were crushed.

East Germans began streaming through rapidly liberalizing Hungary into Austria. On Nov. 9 East Germany opened the Berlin Wall. The ugly, brutish regime, which had long distinguished itself by shooting desperate people seeking to escape to freedom, evaporated.

The other European Communist autocracies fell as well. Bulgaria dumped its ruler of 35 years, Todor Zhivkov. The tottering Czech government yielded power in the so-called “Velvet Revolution.” A mixture of popular demonstrations and military revolt unseated the monstrous Ceaucescus in Romania.

Despite all of the problems that have bedeviled the newly free countries since, the collapse of communism remains a fantastic triumph of the human spirit. With minimal bloodshed, hundreds of millions of people overthrew the worst tyranny in human history. They did what many thought to be impossible: demonstrate that the desire for liberty could defeat the desire for power.

There were heroes in all of the Communist countries. Average people willing to speak out, demonstrate, and demand their rights as human beings. Average people willing to say no to the apparatchiks who had so long lived off the workers they were supposed to represent.

A few people stand out. Alexandr Solzhenitsyn, the Soviet novelist who chronicled the horrors of the gulag and stripped the Soviet regime of any claim to legitimacy. Dissidents like Andrei Sakharov, who was banished internally after protesting Soviet man’s inhumanity to man.

Lech Walesa, the electrician who nearly a decade before the Wall’s collapse climbed atop a shipyard wall in Gdansk, Poland to declare that the time of tyranny was over. Although the forces of reaction briefly reasserted themselves, Walesa ended up as Poland’s first freely elected president.

In Czechoslovakia there was Alexander Dubcek, who attempted to give communism a human face. The playwright, and eventual president, Vaclav Havel, called the regime to account for its crimes.

Four decades ago Imre Nagy, Pal Maleter, and thousands of Hungarian revolutionaries demanded freedom and were murdered by the Soviets and their local stooges. In early 1989 Imre Pozsgay broke with his poliburo colleagues, calling the earlier uprising a “popular revolt.”

Perhaps most important of all was Mikhail Gorbachev. He was, of course, a reform Communist, not a Western-style democrat. His crackdown in the Baltic states left blood on his hands.

Nevertheless, he was the necessary transition from Communist totalitarianism to everything else. He loosened the repressive bonds in the Soviet Union. Although events spun out of his control, he was willing to pay that price in order to transform the most murderous political regime in human history.

He also kept the Soviet troops in their barracks throughout Eastern Europe. In the past Moscow had ruthlessly crushed any attempt by subject peoples to lessen, let alone eliminate, Communist repression.

In 1989, however, Gorbachev let Eastern European leaders stand alone. They could not count on the loyalty of their own militaries. Nor could they depend on Soviet aid. In every country but Romania the ruling elites blinked. In the latter they lost anyway.

A decade later much remains to be done. Economic reforms have stalled, political systems have deadlocked, and Communist murderers remain unpunished.

Yet what was only a dream for decades is a reality: the one-time subjects of the Soviet empire are free. Free, free at last.