Senator Edward Kennedy, who died on August 25 after a battle with brain cancer, was one of the giants of American political life. For five decades, virtually every major piece of legislation to advance civil rights, healthcare and the economic well-being of Americans bore his name and resulted from his tenacious, passionate and effective efforts. His commitment to public service was driven by an exuberant engagement with politics, a deep sense of compassion and a belief that every American is entitled to dignity as well as equal justice under the law.

By the time he challenged Jimmy Carter for the Democratic presidential nomination in 1980, Ted Kennedy had become the national tribune of the liberal cause, within his party and without. Stumbles at the start hobbled his candidacy, but Kennedy was unbowed. He carried on, and began winning primaries and accumulating delegates. For a moment, it seemed as if he might snatch victory from the jaws of defeat.

That was not to be. So on the second night of the Democratic National Convention in New York City that summer, Kennedy addressed the delegates. His speech, the most inspired in a career of inspired oratory, was not a concession. It was a call to arms. Kennedy’s was a plea to the party to stay true to “the cause of the common man and the common woman”–a call that, unfortunately, would not be heeded by too many Democratic nominees who would campaign for lesser purposes. “I’m asking you–I am asking you to renew the commitment of the Democratic Party to economic justice,” Kennedy proclaimed, as he outlined the jobs-with-justice pledges he and his delegates had nailed to the party platform. “Simply put, they are the heart of our tradition, and they have been the soul of our party across the generations. It is the glory and the greatness of our tradition to speak for those who have no voice, to remember those who are forgotten, to respond to the frustrations and fulfill the aspirations of all Americans seeking a better life in a better land. We dare not forsake that tradition. We cannot let the great purposes of the Democratic Party become the bygone passages of history.”

Kennedy ended that speech by declaring, “For me, a few hours ago, this campaign came to an end. For all those whose cares have been our concern, the work goes on, the cause endures, the hope still lives, and the dream shall never die.” The struggle for the soul of the Democratic Party went on over the next twenty-nine years, with Kennedy leading the fight for economic justice and a sane foreign policy, a long-term concern about which he penned articles for The Nation. Having witnessed America’s disastrous involvement in Vietnam, Kennedy was an early, eloquent and unwavering opponent of George W. Bush’s Iraq debacle.

Kennedy fought for human rights–especially gay rights, which he embraced before most other politicians–and the great cause of his life: creating a universal healthcare system. He cast the right votes in the Senate, and as his stature grew he even figured out how to get some conservative Republicans to do the same–earning a reputation as a master legislator not because of his compromises but because, even with Republicans in charge, his focus on human needs and the policies that might meet them (family and medical leave, a patients’ bill of rights, expanding school lunch programs, raising the minimum wage, education reform) broke barriers of personality and partisanship. Unfortunately, the Democratic Party often failed to follow Kennedy’s example. Party leaders edged to the right, embracing the centrist caution of so-called New Democrats, compromising with the Southern conservatism of the Blue Dogs.

Kennedy’s early support for Barack Obama’s presidential candidacy, eloquently outlined in his final address to the Democratic convention in Denver last year, was never naïve. Kennedy knew the younger man would stumble and struggle, make mistakes, disappoint the faithful. Kennedy himself had done all these things. But he believed that Obama was made of stronger stuff, the same mettle that led a defeated presidential candidate to deliver a fight-on address to the 1980 Democratic National Convention and then to do just that across the next three decades. It is this understanding that “the cause endures” that made Kennedy so inspiring, and so essential to the political and policy struggles of his time. If he was right to place his faith in Obama, as we now must hope more fervently than ever, the loss of the liberal lion will be a cause of sadness but not a setback. And we will know that on that hot summer night in New York City twenty-nine years ago, Ted Kennedy was right: “the dream shall never die.”