In late 1988, when I chaired the Helsinki Commission, I listened in a dining room in Moscow filled with American and Soviet officials, as a Russian dissident named Lev Timofeyev stood and proposed a toast. Not two years before, he was chopping lumber in a forced-labor camp in the Ural Mountains. Now he was home, and he raised his glass that night to the immediate freedom of “all those people whom we are accustomed to call political prisoners.”

We Americans drank to that, but the Soviets refused to touch their glasses. An uncomfortable moment passed until the editor of the government paper rose to speak on their behalf. He said: “If we are talking about innocent people who were falsely convicted—well, I can support that.” And the Soviets drank, as well.

I don’t want to overstate the gravity of that moment. The distance across that table lay between those who believed that every political prisoner is innocent, and those who believed that some words and some thoughts were worth prison. Neither side won over the other that night. But the editor of the state paper made an important concession: that some prisoners had been unjustly convicted; that there was such a thing as an innocent man in a labor camp; that innocence itself mattered. And from the regime behind the purges and the show trials and the Gulag—from the regime that gave terrifying meaning to the word “disappear”—those words truly carried weight.

The fall of the Soviet empire—and the fall of this Wall—was to a great extent the result of such small concessions, piled up bit by bit, and of the brave men and women who elicited them and called the empire to account for them. When the Soviet regime signed the Helsinki Accords in 1975, its leaders believed that they had scored a great diplomatic coup, and that the provisions committing them to respect human rights and freedom of conscience would be an afterthought, easily ignored.

But inside the Soviet bloc, they were not ignored. They became a rallying cry for those with the bravery to push their masters to live by what they had signed, from the Russian dissident movement, to Charter 77 in Czechoslovakia, to Solidarity in Poland, to heroic men and women like Andrei Sakharov, Elena Bonner, Natan Sharansky, and Vaclav Havel. As Havel said to a joint session of Congress: “We knew a great deal about the enormous number of growing problems that slumbered beneath the honeyed, unchanging mask of socialism. But I don’t think any of us knew how little it would take for these problems to manifest themselves in all their enormity, and for the longings of these nations to emerge in all their strength.”

The Helsinki Accords were central to that awakening. The historian John Lewis Gaddis observed: the Helsinki Accords “meant that the people living under [communist] systems—at least the most courageous—could claim official permission to say what they thought.”

And when that permission was denied, those men and women could point to the signatures of Leonid Brezhnev of the Soviet Union and Nicolae Ceausescu of Romania and Erich Honecker of East Germany, and all the heads of state of the Soviet Bloc, promising otherwise.

In my work with the Helsinki Commission, it was my privilege to add my voice to that great calling to account: to press for a halt to ethnic oppression in Bulgaria, or to speak for the freedom of worship and of movement in Russia, or to plead for the freedom of Ambassador Bota from prison and execution in Ceausescu’s Romania. And it was my joy to watch with the world as this Wall eroded and then crumbled away.

In this Wall—whose exuberant graffiti and blank concrete face sum up the terms of the struggle so well—we saw communism die as an ideal before its body died. Those who were forced to set up this Wall had promised so much—equality, plenty, brotherhood. But they delivered only what Orwell called the prospect of “a boot stamping on a human face, forever.” They called themselves revolutionaries, but they acted out one of the oldest human urges: the urge to dominate our fellow humans. In this Wall, we saw a system that could entrap, but not entice. When it stood, this Wall stood for the division of Europe; but in the battle of ideas, it was also the gray flag of surrender.

Now it is in pieces, and I am proud to own a small one. But though the destruction of this Wall, by cranes and by young men and women with hammers and chisels, was one of the most joyous images of our time, let us remember the darker side of the picture. In the fragmentation of this Wall, let us remind ourselves of the oppression diffused across our world—no longer summed up in as potent a symbol, or as easy a target, but every bit as deadly.

Part of this Wall is in Rangoon, where Aung San Suu Kyi sits under house arrest.

Part of this Wall is in Pyongyang, where schoolchildren are forced to memorize songs in praise of the “Dear Leader.”

Part of this Wall is in Beijing, where young students cannot use the Internet to discover what happened in Tiananmen Square on June 4th, 1989.

Part of this Wall is in Afghanistan, where girls were attacked in the face with acid for the crime of wanting an education.

Part of this Wall is in Saudi Arabia, where men were beheaded for the crime of being gay.

Part of this Wall is in the hearts and minds of terrorists who imprison their own people behind vengeance and violence.

Part of this Wall is in Darfur, where millions have been subjected to dispossession, rape, or genocide.

Part of this Wall is in Tehran, where Neda Agha-Soltan was shot in the heart for daring to ask: “Where is My Vote?”

And part of this Wall, as Dante observed, is in the reality of good men doing nothing in the face of evil. Part of this Wall is here in America, to remind us to keep faith with those shut behind each wall.

On this anniversary, we pledge again to keep that faith—and to remember that each wall, no matter how tall or fearsome, is ultimately an act of surrender, an admission of bankrupt promises. Just as we did 20 years ago, we add our voices to the great calling to account, with faith that our voices will be heard; that those walls will shake and one day fall.

We keep that faith because, in the words of Bobby Kennedy: “Each time a man stands up for an ideal, or acts to improve the lot of others, or strikes out against injustice, he sends forth a tiny ripple of hope, and crossing each other from a million different centers of energy and daring, those ripples build a current which can sweep down the mightiest walls of oppression and resistance.”

Let us renew our commitment to stand up for our ideals, to speak out against injustice, to improve the lot of others, and to sweep down the mightiest walls of oppression and resistance.