With Senator Clinton telling Wellesley students that they should join her campaign to end the Iraq War the way she joined Eugene McCarthy’s campaign to end the Vietnam War in 1968, the nostalgia among the baby boomers in the Democratic Party for the antiwar movement of the 1960s is now out in the open. We suppose it’s for the best. The Democrats can now openly consider whether their party wants to re-adopt the foreign policy platforms that lost it elections in 1968 and 1972 and the policies that sent America into a period of receding international influence that lasted until the election, in 1980, of President Reagan.

Mrs. Clinton’s comments came the same day President Bush was giving his own history lesson. “Bin Laden and his terrorist allies have made their intentions as clear as Lenin and Hitler before them,” Mr. Bush said. “History teaches that underestimating the words of evil, ambitious men is a terrible mistake. In the early 1900s, the world ignored the words of Lenin, as he laid out his plans to launch a Communist revolution in Russia — and the world paid a terrible price. The Soviet Empire he established killed tens of millions, and brought the world to the brink of thermonuclear war.”

The president, whom the left likes so much to mock but who turns out to be a voracious reader, continued: “In the 1920s, the world ignored the words of Hitler, as he explained his intention to build an Aryan super-state in Germany, take revenge on Europe, and eradicate the Jews — and the world paid a terrible price. His Nazi regime killed millions in the gas chambers, and set the world aflame in war, before it was finally defeated at a terrible cost in lives and treasure.”

Mrs. Clinton responded with a statement calling Mr. Bush’s historical analogies “faulty and offensive,” without elaborating. If American conservatives are nostalgic for World War II or the Cold War in the same way that Mrs. Clinton is nostalgic for the late 1960s, it’s understandable. For much of the duration of both wars, Americans had a unity of purpose and a clarity of mission that now seems to be lacking, as some Democrats dismiss the threat from the Islamofascists as hyped or imagined. While some Democrats — and even some Republicans — now shrug at the consequences of an American defeat in Iraq, an American loss in World War II or the Cold War would have been unthinkable.

At least it was unthinkable until Vietnam, and Senator McCarthy. The consequences to Southeast Asia were bad enough — boat people, decades of captivity, and killing fields. The ripples of the American defeat were felt for years, as far away as Africa and Central America and Lebanon. Both the left and the right seem to forget what the world was like in the years after Vietnam, when the Soviet bear was on the prowl. Even today, decades later, Osama bin Laden cites Vietnam along with Somalia as evidence that America would flee from a fight.

Well, we’re fond of history in these columns, and the history of America is largely a history of success, of the triumph of optimism and freedom over oppression and totalitarianism. It’s hard to escape a feeling that the 2008 race will belong to the candidate who can sketch for Americans an optimistic vision, neither of World War II nor the Cold War nor the Eugene McCarthy era all over again, but of what America has always understood it can be — a nation that can solve its problems and build a better world. Kennedy called it the new frontier and Reagan summoned it in his first inaugural when he spoke of our capacity to perform great deeds, to believe that together with God’s help we can and will resolve the problems which now confront us. “And after all,” he said, “why shouldn’t we believe that? We are Americans.”