You know it’s the twilight of a presidency when the chief executive starts worrying about the past instead of the future.

That’s what President Bush, who is not exactly the biggest reader in the country, has been doing. He’s been reading like mad. About the Algerian War of 1954-1962. About the run up to World War II. About the Colonial period and the Revolutionary War.

Some of it, no doubt, is in his environment. He lives in the most historic dwelling in the nation. Pictures of his predecessors line the walls. He occupies rooms once used by Jackson, Lincoln, the two Roosevelts. He sits at the desk where John F. Kennedy Jr. once peeked out of the kneehole panel.

Bill Clinton read a lot, too, but he always was a voracious reader, consuming about 40 books a year, once devouring a book on death during his honeymoon, once telling a reporter that “The Meditations of Marcus Aurelius” was the most important book he ever read. He was in trouble in the White House, too, and he took solace in reading. It is possible that Clinton read more presidential biographies than any president ever.

Mr. Bush has been reading a lot about history, and he has been wondering a lot about history, specifically what his place in history will be, whether history will judge him well or ill. But as felicitous as the phrase is, there is really no such thing as the judgment of history. There are historians, and they often disagree, and there is the historical view, which changes with the angle and the age.

But in our hearts we know what the president is wondering: Will he be regarded as a champion of liberty for pursuing the war in Iraq or simply as a chump? Will he be regarded as courageous for staying the course in the face of criticism or for being stubborn for refusing to alter his course?

The president has a thing about Winston Churchill – many Americans do, not only conservatives but liberals, too – and right now Mr. Bush apparently is thinking that he is a bit like Churchill himself, seeing truths others do not see about the evil abroad in the world, sticking with his beliefs even though the smart set views him with contempt, taking strength from his isolation rather than letting isolation weaken him.

That was the position Churchill occupied during the wilderness years, when he understood the threat that tyranny posed in Europe, when he saw the danger that military weakness in Britain posed, when he understood that appeasement was not the prerogative of the strong but the refuge of the weak.

Churchill was right about Europe in the 1930s – not partly right, not technically right, but completely right. Historians may have their theories and their evidence about Hitler’s intentions and Hitler’s mode of operations, but no credible historian has argued that Hitler was anything but a tyrant who at the very least was willing to make conquests and very likely was hungry for them. The appeasers of Britain and France were wrong, dead and tragically wrong, and what was at issue was not this piece of territory (the Sudetenland) or that (Memel) but freedom itself, which is what Churchill argued.

But Churchill wasn’t always right. His miscalculations in the Dardanelles in World War I had tragic consequences and nearly ended his career, for good cause. And despite that horrific error Churchill is praised in the popular imagination for his fearlessness and determination. But that does not mean that fearlessness and determination are always to be rewarded, which may be the lesson that Mr. Bush takes from Churchill. Among those with fearlessness and determination in Churchill’s century were Stalin, Hitler and Mao.

One of the books the president has been reading is “Troublesome Young Men,” which is Lynne Olson’s chronicle of the conservatives who sided with Churchill while the fashionable people of Britain sided with his great rival, Neville Chamberlain, who wanted peace in his time so much that he forced himself to see it where it was not. Ms. Olson thinks there is more of Chamberlain than Churchill in the 43rd president – though she does not suggest that Mr. Bush is anything of an appeaser.

“Churchill would be amused at the very least by Mr. Bush trying to wrap himself in his cloak,” she said in an interview last week. “Chamberlain, like Mr. Bush, went it alone before World War II, didn’t feel the need to attract a group of allies. Churchill wanted allies and wanted a strong partnership with France and also with the Soviet Union. And unlike Churchill, both Bush and Chamberlain had very little experience in foreign affairs or much interchange with international leaders. They thought they didn’t need help.”

The problem, for Mr. Bush and for his predecessors and successors, is that there are no manuals for the use of power. Presidents cannot consult the index of a book on Lincoln or Churchill and, from the greatest figures of the 19th and 20th centuries, figure out how to approach the problems of the 21st century.

There are lessons of history, to be sure, but they are not as helpful as the history faculty, the History Channel and the History Book Club would have you think. These lessons are not specific; they are moral. They do not tell you when to appease and when to attack. They do not tell you when to consult the experts and when to consult your conscience. They do not tell you when compromise is ennobling and when compromise is unforgivable. They tell you only to be clearheaded about what is important, to have faith in enduring principles, to trust the instincts of the people, to have courage to do the thing that is good and right. The rest is up to the president.