THE INAUGURAL parade route that President Barack Obama is to follow won't take him across Memorial Bridge toward Arlington Cemetery. But American history being what it is, and with U.S. military personnel deployed around the world, Mr. Obama inevitably will take this most moving and evocative ride in the capital before his first couple of months in office are up. And there, en route to a funeral service or an anniversary commemoration, he perhaps will note this inscription on the memorial to the U.S. Naval Construction Battalions:
"With willing hearts and skillful hands, the difficult we do at once; the impossible takes a bit longer."
This slogan, from one of the nation's most storied military units, the Seabees, has a special meaning for this season of hope and renewal in American civic life. The new president will be expected to do everything, and to do it well. He can't, and he won't. No one could.
This isn't merely a matter of high expectations, which in this year of deficits we have in surplus, nor merely a matter of managing expectations, which must be one of Mr. Obama's premier priorities. It is also a matter of presidential pacing.
New American presidents labor under the tyranny of many historical factors, none more oppressive, more distorting, or more distracting than the precedent of "the hundred days"- a phrase that dates not to Franklin Roosevelt but to Napoleon and his return from exile on Elba, his defeat at Waterloo, and his final exile on St. Helena.
Even so, the notion that FDR accomplished the difficult and made a healthy start on the impossible in 100 days is (accurately) part of the American collective memory.
In that period, Roosevelt won passage of more than a dozen pieces of major legislation, including an emergency banking measure, the first big federal relief program, landmark agricultural legislation that paid farmers not to plant crops, the creation of federal insurance for bank deposits, the establishment of the Tennessee Valley Authority and the Civilian Conservation Corps, and even the beer bill, legalizing beer and light wine and, in so doing, lifting American spirits.
This burst of presidential and congressional activity - accompanied on Day 9 by the first fireside chat - wasn't intended to be a model for anything, just as George Washington's decision not to seek a third term wasn't intended to establish an eight-year presidential tradition that wasn't broken until 1940.
"But to the press this business about the hundred days meant a great deal," says William Leuchtenburg, the emeritus University of North Carolina professor who is perhaps the leading authority on FDR. "It has been the mark ever since of a president. A president never reaches a hundred days without someone putting together a report card."
No one's report card can begin to measure up to Roosevelt's, which Mr. Obama almost certainly concluded after having read Jonathan Alter's The Defining Moment: FDR's Hundred Days and the Triumph of Hope." It may also be why the Obama camp shows impatience whenever the subject of the hundred days comes up.
For in truth, it's not only that FDR's hundred days weren't intended to be a model. They weren't intended to be anything. There was no hundred-day plan, no playbook, no nothing - which, of course, explains more about the New Deal years than a pile of wire-service stories and Web sites on Roosevelt's legacy.
"The Hundred Days were to a large extent an accident," Tony Badger, the Cambridge historian who wrote FDR: The First Hundred Days, argues in the latest edition of The Nation.
John F. Kennedy was aware of the tyranny of the hundred-days myth, the victim of it and, in some sense, the author of one of the most poignant effects of it.
His hundred days were modest. The principal achievement, though one that has resonated in history and in the lives of millions, was the executive order on Day 41 creating the Peace Corps. By Day 88 he was up to his eyes in the Bay of Pigs fiasco.
But in his Inaugural Address, Kennedy inoculated himself: "All this will not be finished in the first one hundred days," he said of his presidential vision. "Nor will it be finished in the first thousand days, nor in the life of this administration, nor even perhaps in our lifetime on this planet. But let us begin."
That is not one of the most-quoted passages in one of the most-quoted Inaugural Addresses of American history. We tend to remember the plea to ask what we could do for our country, or the challenge to let God's work on Earth be our own. And yet Lyndon Johnson remembered that line, and on the unforgettable evening four days after Kennedy's assassination when Johnson addressed a stricken Congress and country, he summoned the country and himself to a new challenge:
"Today in this moment of new resolve, I would say to all my fellow Americans, let us continue."
Mr. Obama is unlikely to unveil a hundred-days agenda remotely like Roosevelt's, though he almost certainly will borrow a page from the 32nd president and push for legislation aiding holders of distressed mortgages.
He knows, too, that presidential agendas, especially for the first hundred days, have a way of getting overshadowed by factors outside the control of the White House. Richard Nixon's first hundred days were disrupted by the war in Southeast Asia, Jimmy Carter's by the energy crisis, Ronald Reagan's by an attempt on his life, and George W. Bush's by a contretemps created when an American spy plane bumped into a Chinese jet over the South China Sea.
Everybody - columnists, commentators, senators, supporters, even critics - has a word of advice (or more) for the new president and his first hundred days. Here's mine: Count your blessings and count your promises, but for goodness' sake, don't count your days.