The Accidental President : A sober assessment confirms the greatness of a gawky genius : LINCOLN, <i> By David Herbert Donald (Simon & Schuster: $35; 660 pp.)</i>

At one end of the Washington mall, guarding the Potomac River behind him and looking outward on other monuments to triumph and tragedy, sits Abraham Lincoln in his temple.

Since its unveiling in 1922, the Lincoln Memorial has served as a national altar for everything from regional and racial reconciliation to righteous advocacy of causes left and right, sacred and secular, transitory and eternal. The idea of Lincoln’s peculiar, self-made genius--”unancestried” as poet James Russell Lowell called him--has been necessary to the faith that Americans, especially in fragmented and uncertain times, can have the courage of their democratic convictions.

There have always been many uses for the Lincoln who, as Yogi Berra might have said, “was born in a log cabin made from his own hands.” Enormously useful as well has been Lincoln the Olympian statesman and master rhetorician who, as Garry Wills wrote in 1992’s “Lincoln at Gettysburg,” reconfigured the natural rights tradition in the Gettysburg Address and “revolutionized the Revolution.” As admirably chronicled in Merrill Peterson’s recent “Lincoln in American Memory,” the iconic Lincoln became a huge vessel into which we have poured an unceasing array of cultural mythology.

Any Lincoln biographer must decide how to negotiate this minefield of myth. David Herbert Donald, twice the recipient of the Pulitzer Prize for biographies of Charles Sumner and Thomas Wolfe, and professor emeritus at Harvard, has steered clear of legends and delivered a one-volume study of Lincoln’s life that will augment and replace the previous modern standards by Benjamin Thomas (1953) and Stephen Oates (1977).

Donald’s “Lincoln” is a masterful scholarly achievement. Indeed, the legions of readers and television viewers reached by Gore Vidal’s “Lincoln” (1984) will find in Donald’s work a kind of factual gyroscope, a marvelously researched and well-crafted reconstruction of the 16th President’s life, beginning with a brief account of his real ancestry, in which Lincoln was not much interested, and ending at the transcendent moment he died in that crowded room across the street from Ford’s Theatre.

During the 1930s and ‘40s, the era when Carl Sandburg’s massive Lincoln came to dominate the American imagination, Donald’s mentor, James G. Randall, played the leading role as critical scholar to Sandburg’s singing poet. Randall’s Lincoln was moderate, the vital centrist who ultimately resisted the radicalism of his era and saved the Union. Much, though not all, of Randall’s perspective on Lincoln survives in Donald.

In an interesting way, Donald, a historian of conservative instincts, has observed and participated in decades of change in the methodology and subject matter of American history. In his important collection of essays, “Lincoln Reconsidered” (1961), he was one of the first to call for the serious study of the “folklore Lincoln.” Moreover, he was an early reviewer and energetic supporter of Vidal’s novel. Perhaps in this new biography, Donald is playing the careful scholar to Vidal’s perversely entertaining novelist, not unlike his mentor attempted to be for Sandburg’s proletarian romanticism.

Donald’s biography is foremost the product of painstaking research and a lifetime of reading in the Lincoln archives and literature. It is a definitive version of Lincoln’s personal story told, as Donald says, about “what he knew, when he knew it, and why he made his decisions.”

The book is written with an elegant restraint that may frustrate some readers hoping for more drama or speculation about the turbulent events swirling around Lincoln’s daily life. But Donald has effectively used Lincoln’s own language--the famous speeches and state papers, public letters and the inexhaustible trove of the President’s own jokes and tales--to develop the story.

Donald carefully demonstrates just how much Lincoln was a product of frontier poverty, minimal formal schooling and a rolling stone journey through a variety of occupations in his 20s. Lincoln loved his stepmother, Sarah Bush Lincoln, but was extremely ambivalent about his father, Thomas Lincoln, loathing Thomas’ work in farming and carpentry. Self-taught in grammar, bookish to distraction, fiendishly ambitious, a backwoods rumbler when he needed to be (he even accepted one challenge to a duel), Lincoln made it into the Illinois Legislature by his mid-20s.

He fell almost naturally into the study and practice of law, and Donald makes the legal career, balanced with the personal story of his tempestuous marriage to the well-born but emotionally high-strung Mary, a central theme of the book’s first half. Donald musters sympathy for Mary (the sad-faced lawyer riding the circuits for months at a time was not easy to live with), but in the end she is portrayed as an irretrievably tragic woman.

Even as the beleaguered President is about to be elevated to a second term in that momentous election of 1864, one can still wonder at how this prairie lawyer who never seemed to fit into his clothes, this gawking “backwoods Jupiter,” became the leader of the republic in its greatest trial. Donald, nevertheless, is astute at showing how contingency combined with Lincoln’s own political genius to make him President, and how sheer courage and political acumen helped him endure vilification that no chief executive had ever known.

These pages feature many wonderful first encounters with Lincoln, such as the Virginian who describes the President-elect in 1861 as “a cross between a sandhill crane and an Andalusian jackass . . . vain, weak, puerile . . . without manners, without moral grace.” Lincoln’s grace was of his own manufacture; he was “awkwardly charming,” as Donald says, able to laugh longest at his own jokes and at himself.

Lincoln’s ultimate success as a politician emerged, of course, from a string of defeats, including the epic struggle for the U.S. Senate with Stephen A. Douglas in 1858, told engagingly here, but interpreted negatively, and a bit oddly, as debates that did not address major questions of “public policy,” other than slavery expansion and racial equality. Lincoln the agitator, who predicted over and over that a “house divided” could not stand, and who seriously intended to put slavery on a course of “ultimate extinction” is not the one Donald most admires. It is the pragmatic Lincoln, the conciliator, the moderate Henry Clay Whig whom Donald most appreciates.

Lincoln’s presidential candidacy in 1860 was a product of fate, the tenacious labors of his Illinois managers, and the volatile party disintegration and sectionalism that was tearing apart the Union. As President he faced the unprecedented turmoil of the secession crisis as, in Donald’s words, an “inexperienced leader with a limited personal acquaintance . . .” and “inadequate information. . . .” There was some truth to Lincoln’s clever self-deprecating claim that he was President “by mere accident.”

So how did this man whom so many considered “not up to the job” become our greatest President? Donald’s overarching answer to this old question is set in Lincoln’s own words in 1864: “I claim not to have controlled events, but confess that events have controlled me.” But we also learn much here about Lincoln’s brilliance in creating political coalitions in his party and Cabinet, his quick study of military strategy, his capacity for moral growth and imagination, his desire to prevent the war from becoming a “remorseless revolutionary struggle,” but his ruthlessness in prosecuting it when it became just that by 1862-63.

A strength of this biography is Donald’s analysis of wartime politics, internecine Cabinet battles and the way the Lincoln Administration teetered on the brink of disaster with each Union military failure. Events indeed were in control, but Lincoln, isolated in the White House, daily and inexplicably submitting himself to endless petitioners and job-seekers, kept an anguished faith that all the suffering for which he was responsible had a purpose.

According to Donald, the essentially unchurched Lincoln believed in a “fundamental fatalism” that saw people as “instruments in God’s hands.” This religious outlook is apparent in Lincoln’s most famous wartime speeches, but Donald refrains from extended analysis of how deeply rooted these ideas were in American thought.

A providential conception of American history, with notions of apocalyptic rebirth and necessary suffering, sustained Bible-reading Americans on both sides during the Civil War. Lincoln’s magnificent second inaugural address, with its prayerful explanation of the war as God’s retributive justice, is aptly described by Donald as an unprecedentedly wrathful doctrine of absolution for both North and South.

Although slavery and emancipation are portrayed as Lincoln’s greatest intellectual and political challenges, Donald looks away a little too easily when explaining why Lincoln held to colonizing blacks as long as he did. Donald’s interpretation of the language of “rebirth” in the Gettysburg Address has more to do with republicanism than black freedom. Moreover, we hear precious few black voices (amid countless Northern politicians and editors) responding to emancipation at its various stages.

But Donald demonstrates how the Declaration of Independence’s first principles, especially about human equality, sustained Lincoln as he secretly drafted the Emancipation Proclamation and kept it in a drawer at the War Department in 1862, refusing to back away, even in the darkest hours of 1864, from the notion that the war should be fought to end slavery.

Donald’s Lincoln is a humanized, demystified figure: cautious, brilliant and lucky, the pilot who kept trying to steer the ship to the middle of the river while imagining the gradual, if inevitable, abolition of slavery. In the end he was the leader both of massive destruction and of a reinvented Union. Donald’s Lincoln holds up and comports well with W.E.B. Du Bois’ description of him in 1922 as “a big, inconsistent, brave man.” “I love him,” wrote Du Bois, “not because he was perfect but because he was not and yet triumphed.”

“Lincoln,” read by James Naughton, is available from Simon & Schuster on four cassettes ($25; abridged).