The Berlin Wall always was a symbol of the superiority of freedom over oppression and of the free market over a controlled economy. Those two aspects — politics and economics — were as much a part of it as the gray paint on its east side and the colorful and taunting graffiti on its west side.

The symbol is gone, but those lessons must remain forever.

Today marks the 20th anniversary of the day Germans, from East and West, began to tear down the wall and reunify. It was a day in which the entire world seemed to exhale after decades of a tense Cold War many felt would last forever. It was, for many, the beginning of the real end to World War II, defined for them by years of war, followed by more than 40 years of oppression and occupation. And it was the beginning of a more chaotic world, defined by ideologies and terrorist threats rather than a superpower standoff.

Experts have argued ever since about what brought down the wall and ended the war. By now it seems clear President Ronald Reagan played perhaps the biggest role, with help from British Prime Minister Margaret Thatcher. Reagan knew how to negotiate through strength. He engaged the Soviet Union directly while building the U.S. military into something clearly designed to send a message.

But Mikhail Gorbachev's role also was important. He abandoned the communist "class struggle" dogma, then made it clear he would not hold on to the Soviet satellite states by force. The evidence is he saw the economic realities, made clear by the expansion and high living standards in the West, particularly the United States. That he recognized this and allowed the Soviet Union to collapse without spilling blood is remarkable.

When the wall went up, it was because so many people were fleeing to the West that the obvious advantages to freedom and capitalism over communism were becoming embarrassing to the East. Over the ensuing years, those differences grew only starker, but they were mostly hidden from view.

It was fitting, then, that once the wall came down it became a part of the capitalist economy itself. It was broken into fragments and sold as souvenirs. Many pieces sit in American homes today. Gorbachev himself ended up doing commercials on American television for a pizza company.

These lessons are important. Many young people in Germany today, particularly in the East, have begun to romanticize life under the old regime. A recent poll by the German government found that 57 percent of people in the East said communist rule was, on balance, mostly positive.

They are important because here in the United States, government has begun to assert greater control over the economy, ostensibly in temporary ways to avert catastrophe.

If the world would always remember the wall — the real wall with its Stasi secret police and its gunshots for people who tried to climb from East to West — the way forward would be much more clear.