BOOK REVIEW / Little noted, long remembered : 'Lincoln at Gettysburg' - Garry Wills: Simon & Schuster, 17.99 pounds - Godfrey Hodgson on the hidden meanings behind a famous speech

THIS IS, there is no other way to say it, a stunning book. Garry Wills has taken a subject about which everyone, at least in the United States, thinks they know all that is to be known. He has gone on to show how much of what we thought we knew happens not to be quite so, and that in an important sense we have missed the main point altogether.

His subject is that most hackneyed of texts, President Lincoln's Gettysburg Address. What most educated people in England know of it, perhaps, is that it was a speech of noble eloquence over the dead who fell in the decisive battle of the Civil War, and that it ends with the hope that 'government of the people, by the people, for the people, shall not perish from the earth'. One might remark in passing that many of those who have had leading responsibilities in British parliamentary democracy since 1863 seem either not to have understood or not to have shared that aspiration.

To Americans, of course, who believe passionately in democracy, it is far more familiar. It has long been one of the sacred texts, along with Thomas Jefferson's Declaration of Independence, the preamble to the Constitution, and Lincoln's own Second Inaugural, of what can only be described as a kind of political religion. That tradition still lives. In our own time, John Kennedy's 1961 Inaugural Address and Martin Luther King's 1963 'I have a dream' speech have carried it forward.

Garry Wills has gone to work on this brief text with the tools of a polymath. He is a historian and a student of American politics - he holds a chair of American Culture and Public Policy at Northwestern University in Chicago - and he has written brilliant biographies of Richard Nixon and Ronald Reagan as well as penetrating studies of American religion and of the iconography and semantics of the American political tradition. He is also a classical scholar, educated by the Jesuits. But his dazzling intellectual gifts are always in the service of elucidating things that matter.

Many Americans know that Abraham Lincoln's imperishable words followed a far longer and more highly-wrought oration by a Massachusetts worthy called Edward Everett. The contrast is often given a mildly populist twist: the Harvard professor of Greek boring on for hours, only to be flattened in the contest by a few words from the homespun frontier railsplitter.

Wills shows it was not quite like that. For one thing, it was Everett the crowds came to hear; to invite the President was an afterthought on the part of the State authorities. For another, Everett was a man of genuine distinction, and not an unworldly academic by any means; he was governor of Massachusetts, congressman, senator, ambassador to Britain and Secretary of State as well as a Greek scholar and a Harvard professor.

Garry Wills also shows, in great detail, that both the Harvard professor's lengthy oration, and the naildriving speech by the self-educated Western president, were influenced by the same tradition and followed it closely: the tradition of Greek funeral oratory. Lincoln knew about ancient rhetoric, Wills suggests, because he had read the Lectures on Style by a Scots expert, Hugh Blair, who was much used by American public speakers at the time.

Wills analyses Lincoln's 272 words into such technical devices of ancient Greek rhetoric as the contrast between the epainesis, the praise of the dead, and the parainesis, addressed to the living. He shows, to take only a single example, that when Lincoln said 'the world will little note, nor long remember what we say here, but it can never forget what they did here', he was following literally the logos / ergon (word / deed) distinction that was traditional with Greek orators such as Pericles and Gorgias.

This is fascinating stuff. Indeed, it makes the hair on my head stand up a little to see the close parallels between Lincoln's text and Gorgias's funeral oration of about 400 BC. But that is an almost inconsequential historical by- way in comparison with Wills's main point. What he is saying is that the Gettysburg Address was not just an elegant celebration of the dead; that Lincoln deliberately seized the occasion of the dedication of the Gettysburg war cemetery, where thousands of soldiers from both armies were still being buried or reburied when he spoke, less than five months after the battle, to make a political point. And that was nothing less than to redefine the fundamental premise of American democracy.

The Constitution of the United States not only tolerated slavery, it enacted it, albeit in somewhat shamefaced and indirect language. It therefore qualified - fatally qualified, for three generations - what Jefferson meant in the Declaration when he said that Americans held it as self-evident truth that all men were created equal. Jefferson, after all, like Washington, was a slaveowner. So, to put it simply, he meant that all men were created equal except black men, and in the context of his time by 'men' he meant 'males', not 'humans'.

The great quarrel between North and South, with its torrents of oratory, its subtle constitutional hairsplitting, the fire-eating defence of slavery by the Southerners, and the passionate abolitionism of New England, never succeeded in resolving the fundamental ambiguity in the Declaration and the Constitution, the two fundamental laws of American democracy. It took the war to do that. Lincoln himself, who either held racist views or more probably found it politic from time to time to pretend that he did, was notably unwilling before the war to open that Pandora's box. Even when he proclaimed the emancipation of the slaves, less than a year before the Gettysburg speech, he did so in a notably cautious way. Lincoln grasped that the decisive defeat of Lee's desperate left-hook on Washington at Gettysburg changed everything.

Garry Wills's thesis, argued with masterly advocacy, is that what Lincoln was about at Gettysburg, quite deliberately and consciously, was abolishing that fundamental ambiguity in the American commitment to equality. 'This was the perfect medium for changing the way most Americans thought about the nation's founding acts,' says Wills. Lincoln was moving out beyond Jefferson's already daring assertion of political equality, and staking out a position, of equality for all citizens, which remains even now an aspiration, though one with irresistible magnetic force.

'He came to change the world,' Wills says, and there are echoes of Christian theology in what he is claiming, though he is notably irreverent in his dicussion of Lincoln. 'No other words could have done it. The miracle is that these words did. In his brief time at Gettysburg he wove a spell that has not, yet, been broken - he called up a new nation out of the blood and trauma.' It is a thesis with vast implications, and this book is a worthy statement of it.