No sense of history without a good biography When Robert Caro published The Passage of Power, the fourth volume of his Lyndon Johnson biography, last week, Bill Clinton reviewed it reverently in the New York Times Book Review. That gives an idea of how seriously Americans take presidential biographies. In an ordinary world, presidential biographers write about presidents and not vice versa. Mr Clinton, however, has always had an appetite for big lives. Over Christmas, he urged people to make a gift of David Donald's Lincoln. George W. Bush, too, likes biographies. He spent some of his final days in office with Michael Kazin's book on the Christian firebrand and three-time Democratic presidential candidate William Jennings Bryan. Cynics would say the two politicians are proving their shallowness, not their depth. They're taking from history what they can use - leadership secrets - and throwing away the husk. But this cannot be the full story, because Americans unlikely to exercise even a bit of power await new biographies just as eagerly. Two decades ago, US readers were partial to sweeping histories of the sort written by Paul Johnson and Paul Kennedy. They still like war books, but history is doing less well. Biography is the kind of history Americans have the steadiest taste for. There are some ignoble reasons for this. The internet has reorientated even educated people's attention towards gossip. There are also some understandable reasons, including the ability of biography to ease us into deep conceptual waters with quirky details and engaging stories. William Silber's forthcoming biography of former US Federal Reserve chairman Paul Volcker will probably teach the median American reader more about macro-economics than Allan Meltzer's multi-volume history of the Fed or Friedman and Schwartz's Monetary History of the United States. But biographies give us more than just a sugar-laced kind of history. At their best, they show us a facet of history that history itself cannot. Most historians filter their subject matter through the preoccupations of their own time. Generally, this is a good thing, enabling us to see, in hindsight, what was ultimately important in a period. Paul Berman's A Tale of Two Utopias transformed thinking about the 1960s when it was published in the late 1990s. It showed that the sixties were less political and more social than people appreciated. Women burning their bras were not a sideshow - they were the show itself. What some had taken for the pith of the 1960s - the ideological struggles among socialist movements - was in retrospect less important. The best historians have a gift for abstraction. They reveal what people were actually doing, underneath what people thought they were doing. But this can be a drawback. It can make the mood of a bygone society opaque to us. Abstraction isn't always terribly fecund. A bunch of good stories is more apt to generate a profound principle than a profound principle is to create a bunch of good stories. That is where biography comes in. The most interesting thing about history, the source of all its tragedies, is that intentions and ideals are so very different from deeds and effects. The gap between LBJ's ideals and his deeds is unusually wide. Through punctilious attention to detail, Mr Caro hopes to capture what in a recent New York Times interview he called "two threads, bright and dark." Johnson was devious in acquiring power, idealistic in wielding it. He was dishonest and corrupt, and sincerely concerned about poverty and racial equality. You can describe him as one of the worst presidents or as one of the best, depending on whether you judge him by how he sowed or what he reaped. That account, though, is incomplete. Caro's Johnson, like Macaulay's History of England, is the towering result of a serious miscalculation. Mr Caro has bitten off more than he can chew. He has embarked on a project so ambitious that a normal lifespan will not suffice for its completion. In the latest instalment, Mr Caro spends almost 500 pages on the month-and-a-half that passed between Kennedy's assassination in November 1963 and Johnson's first state of the union speech in January 1964. It was during those months that he laid the foundation for the most eventful presidency since Franklin Roosevelt. That presidency was about welfare and warfare, neither of them properly funded. In this it resembles George W. Bush's presidency more than any other. LBJ's escalation of the Vietnam war went so wrong so quickly that hubris could be easily diagnosed. His astonishing escalation of the welfare state was, in retrospect, equally misguided, and of a piece with his Vietnam policy. It is just that it took four decades for the hubris to become apparent. Mr Caro has given us a monument of biography. As history, though, his "bright and dark" assessment of LBJ looks less astute.