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.