A friend notes that March 4, 2005, the day on which this is written, is exactly 72 years to the day later than the day on which Franklin Roosevelt took office as president and assured Americans that “the only thing we have to fear is fear itself.”

Exactly 72 years before that, Abraham Lincoln took the oath of office and appealed to “the mystic chords of memory.” Seventy-two years before that, George Washington took the oath of office as the new nation’s first president.

Lincoln began his address at Gettysburg with the words, “Four score and seven years ago” – a reminder that the span of time between the great battle and the Declaration of Independence was not much more than the biblical lifespan of “three score and ten.” We stand today one lifetime away from Franklin Roosevelt, two lifetimes from Abraham Lincoln, and only three lifetimes away from George Washington.

1933, 1861, and 1789 were all turning points, moments when men mattered. Men of piercing intelligence and farsighted men of extraordinary and unusual character. Washington was a leader who knew he was setting precedents for a republic that he believed would some day be continental in extent; he purposively kept himself remote from his contemporaries and strove to control his raging temper. He unleashed the talents of the young Alexander Hamilton, whose Federalist papers had done so much to secure the ratification of the Constitution, to shape a strong and fiscally reliable federal government. But he alone had the prestige to hold the new republic together when it was split by partisans on either side of what was then a world war between monarchist Britain and revolutionary France.

Lincoln came to office facing the dissolution of the nation Washington had welded together a lifetime before. Little known to his fellow citizens, condescended to by his Cabinet, he pursued a zigzag course through military failure to success, from a promise to honor the laws that upheld slavery to the proclamation that slavery was no more, from savage battle to “malice toward none and charity to all.”

Another president might have let the Confederacy go – Lincoln’s predecessor thought he couldn’t do anything else – or might have compromised and readmitted the Southern states with slavery intact. Lincoln ensured that the promises made in the Declaration a lifetime before would be kept, if not fully in his lifespan then some day in a reunited United States.

In the lifetime between Lincoln’s first inauguration and Roosevelt’s, the nation grew into an industrial giant – swelled with immigrants as no nation had ever been – and into potentially the greatest military power on earth. But when Roosevelt took office, the economy was in a deathly downward spiral and demands for radical change were in the air.

Roosevelt’s economic policies, aimed at freezing the economy in place, have been faulted for prolonging the Depression and choking off economic growth. But critics should also credit him for what he didn’t do. Roosevelt could have nationalized the banks in 1933; instead, he insured their depositors. He could have nationalized industries, as Woodrow Wilson had done in World War I. Instead, he regulated them, imposed unions on their managements, and worked cooperatively with their executives in building the war industries into the arsenal of democracy that won World War II. In the process, the United States became the world’s greatest military power, with responsibilities it has been grappling with ever since.

It seems unlikely that George W. Bush will be a giant in history like the presidents inaugurated 72, 144, and 216 years before. The threats to the nation are not as great. Yet his presidency may come to be seen as another turning point, and one in which the president’s character, and the choices he need not have made but did make, could shape the nation for a lifetime to come.

Mr. Bush, as Yale’s John Lewis Gaddis has noted, has transformed American foreign policy more than any president since Roosevelt and has decided to wield America’s power proactively to advance liberty and democracy around the world. The recent advances toward democracy in the Middle East suggest he is on the side of history.

Mr. Bush is also working to transform government from the industrial era programs of Roosevelt’s day to post-industrial era programs and has had some successes – but how much is still uncertain. There will be turns in the road ahead, but Mr. Bush seems to be setting America on a course that was not inevitable and which could shape the nation for a lifetime to come.