WASHINGTON This is a delight of a summer book history for the beach, politics for the deckchair, and waspish entertainment come rain or shine. Nigel Hamilton takes Suetonius's set formula for mini-biographies in The Twelve Caesars - where they came from, what they did in power, who shared their beds - and uses it to work over every US president from FDR to George W. Bush. Scope for jokes, gossip and something much more a space to set a dozen leaders everyone knows in a context where secrets fall out of the cupboard and comparisons come naturally.

Who emerges well? Roosevelt, of course, with Eisenhower, Truman and Reagan not far behind. And badly? Bush Jr, inevitably; the warped, sometimes demented Nixon; but John F Kennedy, hopelessly in thrall to a world of lust, isn't pavilioned in praise either. And, because he is essentially telling a sequential story as well as sketching his portraits, Hamilton also charts the rise, and perhaps the fall, of the American empire in human terms.

We don't think of Hoover or Coolidge as any kind of Caesar. After Woodrow Wilson, indeed, the US turned in on itself, sinking first into hedonism then into crunching depression, until the ravenously ambitious Roosevelt won the White House and delivered a message that resounds to this day in coalition land. “The country needs, the country demands, bold, persistent experimentation. Take a method and try it. If it fails, admit it frankly and try another. But above all, try something.”

That's the wonder of history. The past isn't dead; it offers constant resonances. Here's Harry Truman, the humble farmer and haberdasher, flying off to a Pacific island to meet a victorious, vainglorious General MacArthur “like Julius Caesar first attempting collegial relations with Pompey” and learning, to his profound distress, that the victor of Inchon is a political imbecile who will soon be advocating nuking China. Here's Truman again, going back to the farm after seven hard years, quoting Cincinnatus and George Washington, but taking only modest savings and a military pension of $112.56 a month home to Missouri with him.

Wild military top brass out of control; recession cures that work or fail; public service greed and extreme frugality. You can't read how a doubting, reluctant Lyndon Johnson - spoonfed prospective triumph by a Pentagon always asking for more, goaded by right-wing zealots - was sucked ever deeper into Vietnam, then stuck there because there was no peace with honour, without thinking of Afghanistan today. Could Johnson have broken free in the end? No because Nixon was, covertly, offering the Vietnamese something malign - the promise of a better deal if they didn't stop fighting before the election. It was a pact with the devil that Tiberius might have relished.

The more distant in time the presidents Hamilton examines, the more interesting - because unfamiliar - they become. We know Jimmy Carter was clever and earnest but a hopeless micro-manager. We know we all got Ronald Reagan wrong. We know Gerald Ford was way smart enough to talk and chew gum at the same time. Nevertheless, in every tenure, the worlds of Washington and Rome can seem to touch across the millennia.

It's important, too, to see these 12 presidents as children, husbands, fathers - because private and public aren't separate, but crucial to the longer view. It matters that FDR dived into marriage young with an ugly cousin to get away from his doting mother. It matters that his love for Lucy Mercer drove Eleanor Roosevelt to baleful despair. It matters that LBJ “was rude, boorish, taunting, humiliating, and thought nothing of urinating into the sink in his office while still interviewing someone”. It matters that Jacqueline Bouvier was not the love of John Kennedy's life but “a cultural snob par excellence” who evoked “tantalisingly little initial interest or affection on JFK's part” before “a sullen, desultory romance” made her the necessary wife and - like Lady Bird Johnson - a kind of mute brothel supervisor, finding and fielding young aides and interns who could keep him happy for an hour or two (even under the dinner table).

It matters that Nixon's family never realised what those around him knew that he was a congenital, self-deluding liar. It matters that Nancy Davis rescued Reagan from the pits that he'd wallowed in since Jane Wyman walked out of their marriage without her, there would have been no Reagan presidency. It matters that George Bush Sr - dogged by rumours of infidelity - failed to win a second term and took defeat so badly that his eldest son felt disastrously driven to restore family pride. And, beyond any doubt, the Hillary and Bill relationship matters still.Hamilton, like Suetonius, is full of curt dismissals and insouciant judgments. He hasn't produced one dull essay in 12. But don't write off his Roman echoes as gimmicks contrived for facile effect. You find humility and rapaciousness, madness and brilliance here, just as you found them in the days of another empire, and thus you learn the most basic lesson of all. Thousands of years may come and go, but power, and the people who seek it, sometimes ordinary people, sometimes maniacs, sometimes somewhere in between, remain much the same.—Dawn/The Guardian News Service