(FORTUNE Magazine) – The analysts, commentators, political scientists, and historians will examine the Iowa caucuses and the New Hampshire primary in February for hints of what is happening to American politics. They might do better to read an extraordinary issue of FORTUNE that appeared precisely 45 years earlier.

The issue was called "USA: The Permanent Revolution," and it arrived on the nation's doorsteps in February 1951, just as Americans were adjusting to their new role atop the greasy pole of international politics. The magazine was later republished as a book, and in the introduction Russell W. Davenport argued that it was "incontestable" that America's importance on the world stage "has to do not merely with American economic and military power, but with the fact that Americans may yet be able to solve some of the social, economic, and political problems that have been tearing the free world apart."

That is true again nearly half a century later, but in a very different way in a very different world. And the biggest difference has to do with our own internal politics, which is bereft of the confidence, the stability, and the vision that it once possessed.

The notion that the U.S. political system is in crisis has become a commonplace on the television chat shows, in the country's political journals, and in the national conversation. The two parties claim a smaller percentage of the nation's loyalties than ever before. Moreover, party identification is declining at exactly the time when politics in Washington has become more partisan than ever. The nation's voters have lost confidence in their leaders and, more alarming still, in the system itself.

The essays on America at midcentury have a quaintness about them now, at century's end. They wax poetic on "the American way of life" and linger on "the strenuous life." They throw out large challenges: "Big Business," said the editors, "has something to answer for."

But the essays portray a country of exquisite political balance, a miracle of physics as applied to politics. The "conservative" party claimed as its heroes a president (Abraham Lincoln) who freed the slaves and another one (Theodore Roosevelt) who bedeviled the trusts. The "liberal" Democratic party produced such conservatives as John C. Calhoun and Grover Cleveland.

Indeed, the very stability of the system, FORTUNE's editors argued in 1951, derived from the internal instability of both parties. They pointed out that each party had a left wing and a right wing. Even when Franklin Delano Roosevelt's liberal wing predominated, it was unable to eliminate the conservative wing, which at times seemed to exist simply to torment the leader of its own party. When the conservative wing of the Republican Party dominated, it was unable to wipe out the progressive wing; indeed, GOP liberals even managed to nominate a presidential candidate from their own ranks, Wendell Willkie. "It is through this internal struggle that the American political party achieved its highest function, namely, that of national integration," wrote the editors.

And thus, in the pages of a 45-year-old magazine that speaks blithely of "the American Proposition" and "the American System," lies an important insight about the American Predicament today.

To wit: Today's Democratic Party no longer possesses much of a right wing. The tragedy of the party's loss of power in 1994 isn't that a number of entrenched chairmen such as John Dingell of Michigan, who transformed the Energy and Commerce Committee into a sitting grand jury, lost their power bases. It is that, in losing the House, the Democrats lost so many of the conservative House members who were struggling, often without success, to give balance to the party.

Nor does today's Republican Party possess much of a left wing. Not so long ago, GOP Senators included such figures as Charles Goodell and Jacob Javits of New York, Clifford Case of New Jersey, and Charles M. Mathias Jr. of Maryland. Just as Picasso had his blue period, even Herbert Hoover had his liberal period. So too did Richard Nixon, the born-again Keynesian, welfare reformer, and environmental crusader.

But that's all gone. The last conservatives in the Democratic Party are either retiring, as Sam Nunn of Georgia is doing, or deciding they'd rather switch than fight, as Richard Shelby of Alabama did. Meanwhile, liberals in the GOP have moved from an endangered species to near extinction.

The parties still aren't entities of ideological rigidity on the European model. But it is incontestable, as FORTUNE liked to say 45 years ago, that they have lost their wings. Those wings provided ballast and they provided balance. And without them the system may not be able to fly.

David Shribman is Washington bureau chief for the Boston Globe and a Pulitzer Prize-winning political reporter.