BERLIN -- The righteous rage in the streets of Tehran is familiar to Berliners. They recall their own demonstrations that doomed the hated Berlin Wall two decades ago. Berliners, hopeful and sympathetic, see lessons in their past for the demonstrators in the Iranian capital.

Films and photographs at exhibitions throughout the city document how "power to the people" can sometimes beat extraordinary odds. The exhibitions were planned long before the protests in Iran were a gleam in the eye of candle-carrying Iranians. Nobody here discounts the odds against the Iranian masses -- the turmoil can lead to the results of November 1989 in Berlin or to the tragedy of Tiananmen Square.

History in the making lacks the clarity of history recalled, but similarities of circumstance are nevertheless striking. Visitors to the Sony Center in Potsdamer Platz, for example, watch with widened eyes at a videotape of John F. Kennedy's speech on June 26, 1963, poignant in painful remembrance, expressing solidarity with the residents of a divided city.

His dramatic assertion, "Ich bein ein Berliner" -- "I am a Berliner" -- rings in the ears of Berliners today. So, too, Ronald Reagan's exhortation at the celebration of the 750th anniversary of the founding of Berlin: "Mr. Gorbachev, tear down this wall."

Several of his closest advisers argued against making such a dramatic declaration, for fear of antagonizing Mikhail Gorbachev. But the Gipper knew that his words would tell people far beyond Berlin that America stood with them, and would take heart.

President Obama heard similar appeals to timidity this week in Washington -- he shouldn't risk antagonizing Mahmoud Ahmadinejad and the mullahs in Tehran if he wants to parley with them. Like Reagan, the new president showed a little spunk at last, finally asserting solidarity with the demonstrators. There was none of the Kennedy bravado or Reagan dramatics, but it was nevertheless welcome.

The debate now focuses on the nature of Barack Obama's leadership as he faces his first crucial foreign policy crisis. Germans, like Americans, argue over whether his measured approach will actually work, or whether his caution will be taken in Tehran for weakness and irresolution. They compare the Obama approach with Angela Merkel's mettle in demanding from the first a recount of the votes.

For all of his admired rhetorical flourishes and reiterated outrage, President Obama sounds more unassuming than assertive, more like a well-meaning appeaser than a tough-minded analyst. Many Germans concede that the president's Cairo speech probably inspired the demonstrators in Tehran, but some of his remarks since have seemed to float like mere magic bubbles blown from a wand, popping harmlessly when they come to earth.

Confronting tyranny requires courage. The sweep of history that took Berliners to a triumphant dance on the wall at the Brandenburg Gate was long in the making. The lesson for the Iranians is that dismantling a corrupt and oppressive government requires not only courage, but patience and above all persistence.

Germans in the east marched against rigged local elections in May 1989, weary of the same hacks the government put up for "democratic" validation of a popular election. It was those demonstrations, Merkel observed not long ago in a ceremony commemorating the East German demonstrations, that marked "the beginning of the end."

The end did not come quickly or easily. Young men and women here, as in Tehran, risked their lives to confront the government, smuggling out stories of government brutality. No one knew they were creating a revolution. Like the Iranians, the German revolutionaries represented many different points of view. Some craved personal rights, others broader election choices. Others simply wanted the right to leave. But they were unified against a common enemy.

If Reagan's description of the "evil empire" once sounded over the top in the West, it was not so behind the Iron Curtain, where it was appreciated as an accurate description of what they endured every day. Gorbachev's glasnost, which led to the crumbling of both the wall and eventually the Soviet Union, was to the evil empire what Twitter, Facebook and YouTube may eventually become for the Iranian government. President Obama was right to ask the administrators at Twitter to keep its communication channels open in Iran during the marches, sustaining the demonstrators just as smuggled videos bore witness to oppression here two decades ago.

The longer the Iranian protests last, the more sweeping the indictments will become. The demonstrators have already changed Iran -- the men and women in the streets of Tehran threaten to change the Middle East. That may be wishful thinking, but you can't say the Germans haven't been there and done that.