President Obama gave one of his strongest speeches on Saturday, in Selma, Alabama, on the fiftieth anniversary of “Bloody Sunday”—the day of the violently suppressed march that helped lead to the Voting Rights Act, the climactic achievement of the civil-rights movement. Standing in early-spring sunlight on the Edmund Pettus Bridge, Obama praised the American spirit of striving and self-renewal embodied in the moral and physical courage of the marchers: “What greater expression of faith in the American experiment than this, what greater form of patriotism is there than the belief that America is not yet finished, that we are strong enough to be self-critical, that each successive generation can look upon our imperfections and decide that it is in our power to remake this nation to more closely align with our highest ideals?”

Obama’s hymn to the America of constant change is encompassing enough to include every generation, including that of the first black children of a President to grow up in residence at the White House (Malia and Sasha Obama were among the marchers in Selma last weekend). The speech was inspiring, at moments soaring, but, in a sense, the President didn’t need to give it. His presence on the bridge alongside Congressman John Lewis, who had walked at the forefront of the original march and taken the first blows from Alabama state troopers, was eloquence enough. Here was change—here was the picture of a nation, still imperfect, but more closely aligned with its highest ideals. Obama could have spoken as briefly as when Lincoln said, “The world will little note, nor long remember, what we say here, but it can never forget what they did here. It is for us the living, rather, to be dedicated to the unfinished work which they who fought here have thus far so nobly advanced.” Between Gettysburg and Selma there’s a straight line of history and ideas and sacrifice.

A week after Bloody Sunday, President Lyndon Johnson addressed a joint session of Congress, as well as seventy million Americans watching on television. He urged Congress to pass a voting-rights bill, the second piece of landmark civil-rights legislation in less than a year. It was the greatest speech of his Presidency, and one of the greatest by any President. “I speak tonight for the dignity of man and the destiny of democracy,” Johnson began, and from there he kept raising his aim, comparing Selma to Lexington and Concord and Appomattox, to the great turning points in American history. “There is no Negro problem,” he said. “There is no Southern problem. There is no Northern problem. There is only an American problem. And we are met here tonight as Americans—not as Democrats or Republicans—we are met here as Americans to solve that problem.” Johnson said that if America won all its wars and doubled its wealth and journeyed to the stars but failed to solve this problem, “we will have failed as a people and a nation.” He declared that the scene before him gave hope in American democracy: “For the cries of pain and the hymns and protests of oppressed people have summoned into convocation all the majesty of this great government—the government of the greatest nation on earth.”

“All the majesty of this great government”—imagine that phrase being uttered without irony on Capitol Hill today. Or “the outraged conscience of a nation,” or “And we shall overcome.” Imagine a President addressing a joint session of Congress on an issue of such moment and framing it in such starkly moral terms, knowing that he could count on some solid support from the opposition leadership. Amid the cheers and applause, some senators and congressmen sat stone-faced, but no one shouted, “You lie!” Articles of impeachment were not drawn up. Southern committee chairmen didn’t invite George Wallace to come to Congress and rebut President Johnson, as Speaker Boehner recently invited a foreign leader to come embarrass President Obama.

As brutal as the Alabama state police and the Dallas County sheriff’s department were on Bloody Sunday, as violent as the vigilantes were who killed Jimmie Lee Jackson, James Reeb, and Viola Liuzzo in those weeks, as much progress as America has made in fifty years, something has gone seriously backward since 1965: the quality of American institutions. The flap over the historical accuracy of Johnson’s portrayal in the film “Selma” obscured this larger truth. “The real hero of this struggle is the American Negro,” Johnson told Congress, but the context for Selma was a country of functioning institutions. Martin Luther King, Jr.,’s desperate strategy was to dramatize white racism to such a degree that the institutions would have to respond.

There may still be ordinary Americans as brave and committed to justice as the civil-rights movement’s foot soldiers, but we no longer have a national government (or a federal bench, a press corps, labor unions, businesses, religious groups, universities) capable of coming together with the imagination, wisdom, and self-restraint necessary to achieve something on the scale of voting rights. These days, Congress can hardly keep the Department of Homeland Security open without tearing itself to pieces. As Charlie Dent, a Republican representative from Pennsylvania, said to the Times, “We really don’t have two hundred and eighteen votes to determine a bathroom break over here on our side.”

On Monday, forty-seven Republican senators addressed an open letter to the Iranian leadership, declaring that “we will consider any agreement regarding your nuclear-weapons program that is not approved by the Congress as nothing more than an executive agreement between President Obama and Ayatollah Ali Khamenei.” The senators noted that Obama will leave office in 2017, while many of them will go on serving for decades—so why should the clerics pay any attention to the executive branch? The senators didn’t release classified U.S. intelligence on the nuclear negotiations, but it’s not altogether clear what stopped them. They’re doing all they can to sabotage their own country’s position in the talks, practically making themselves the de facto ally of hardliners in Tehran. Try to imagine such actions by America’s elected leaders during the Cold War.

It may be that the postwar decades, with a booming mixed economy, middle-class prosperity, and an agreed-upon enemy, created unique conditions for Americans to address some of the country’s deepest problems, such as a century of Jim Crow. Our problems today, from climate change to economic inequality, seem immovable not because they’re so much harder, but because we no longer have the political tools to budge them. Perhaps that’s why, last Saturday on the Edmund Pettus Bridge, President Obama spoke more about the daring spirit of the American people than the greatness of constitutional democracy. If solutions arise from this generation and the next, they seem unlikely to come from Washington. They’re more likely to start in obscure places like Selma.