As President Bush prepared for his second inaugural, we settled down with an illuminating new book called “Ask Not,” written by a historian, Thurston Clark, about the inaugural address of President Kennedy. That is the speech in which the 35th president declared the most fundamental belief of his tenure, one for which the 43rd president has been mocked for reiterating so often – that, as JFK put it, “the rights of man come not from the generosity of the state, but from the hand of God.”

One of the points that Mr. Clark makes in the book, and that was reiterated in an op-ed article in Saturday’s number of the Times, is that part of the power of Kennedy’s speech came from its autobiographical nature. When he spoke of the torch being passed “to a new generation of Americans – born in this century, tempered by war, disciplined by a hard and bitter peace, proud of our ancient heritage,” he was speaking of his own life in a literal way.

That passage was followed by the new president’s most famous vow: “Let every nation know, whether it wishes us well or ill, that we shall pay any price, bear any burden, meet any hardship, support any friend, oppose any foe, in order to assure the survival and the success of liberty.” This is the phrasing that inspired our expedition in Vietnam and that has stuck in the minds of millions over the years. It is against that declaration that American politics seems to be at such an ironical pass.

For in the election just ended, it was the Republican who, while so different in style, carried the substance of these sentiments to the voters, while it was the Democrat, Senator Kerry, who, while affecting so many similarities of the Kennedy style, campaigned to repudiate these sentiments. It was President Bush who fought for and won the $87 billion in funding for our troops in Iraq that became the symbol of this issue, and it was Senator Kerry, another Massachusetts Democrat, who voted against it and, incidentally, who went on to argue for a more pragmatic, less idealistic foreign policy.

When did this happen? When was the moment at which the Democrats relinquished the mantle of leadership in the struggle for the success of liberty? When, and how? Some say it was relinquished at the Bay of Pigs or, later, during the Cuban missile crisis, when, it turns out, Kennedy signaled he would pull American missiles out of Turkey if the Russians retreated in Cuba. Others reckon Kennedy relinquished the mantle when he authorized the coup that led to the murder of President Diem in South Vietnam.

Others might say that the default came the year President Johnson ran against Senator Goldwater, when LBJ mocked the conservative with the famous advertisement showing a little girl plucking petals from a daisy until an atomic bomb went off. It ushered in an era when the Democrats sought to be perceived as less likely to risk all in the war with the Soviet Union. Still others might suggest the tipping point came when Johnson chose not to run, rather than to see out the fight in Vietnam.

Nixon failed to pick up the mantle. His presidency was marked by retreat in Vietnam and detente with the Soviet Union. He truckled to the Red Chinese. President Carter sounded some of the noblest themes ever uttered by a president, such as his Notre Dame speech, where he marked the point that the great democracies of the world were not free because they were rich but rich because they were free. He engaged, through proxies, the Soviets in Afghanistan. But he kissed Brezhnev and turned his human rights rhetoric against America and the flaws of our allies.

It fell onto Reagan’s shoulders to pick up the mantle of leadership in the global fight for freedom. He abandoned the idea of peaceful coexistence and initiated the rollback that brought the defeat of Soviet Russia, the unification of Germany, and the expansion of democracy in Central America and Africa. It was a vast and sophisticated leadership, involving a rebuilding of the defense budget, the backing of the twilight wars, a brilliant fight against the Sandinistas and other communistic regimes in Central America and the Caribbean, and the greatest presidential act of the 20th century, walking away from the brink of appeasement at Reykjavik.

President Bush turned out to be a transitional figure, and President Clinton lacked the biography that Professor Clark teaches was so important to Kennedy’s inaugural. He was a child of the peace movement, who, in the most desperate hours of the fight for freedom in Southeast Asia, failed to report. As president, he was prepared to use force, at least from the air, as he showed in the Balkans. But he was not a master of it, and he was by instinct a conciliator. He failed to enforce United Nations sanctions in Iraq. Toward the end of his presidency, he made a trip to Vietnam and, en route, told the Associated Press that he had a better grasp now than he once did of what Johnson faced.

It was not until war was brought to our shores on September 11 that America was confronted with a test that a president could not dodge, which is how George W. Bush came to prove the point JFK was making when he said, “In the long history of the world, only a few generations have been granted the role of defending freedom in its hour of maximum danger.” The energy, the faith, the devotion which Americans bring to this endeavor would, Kennedy said, light our country and all who serve it and light the world. And he issued his exhortation to his fellow Americans: “Ask not what your country can do for you – ask what you can do for your country.”