Which is why the publication of details of dozens of intimate letters written by the young Hillary Rodham to a highschool friend has stirred up so much interest, raising anew the debates over how her political ambitions were formed and questions from her enemies about whether she is fit to lead the country.

At the very least, they are a fascinating insight into the emotional turbulence that once lay below the surface of the young student at Wellesley College, Massachusetts, who grew into one of the most scrutinised and yet ultimately inscrutable women at the centre of power in the US.

"Sunday was lethargic from the beginning as I wallowed in a morass of general and specific dislike and pity for most people but me especially, " the 19-year-old Hillary Rodham reported in a letter postmarked 3 October 1967.

9And in another missive that year, she had pondered her own developing personality:

"Since Xmas vacation, I've gone through three-and-a-half metamorphoses and am beginning to feel as though there is a smorgasbord of personalities spread before me.

So far, I've used alienated academic, involved pseudo-hippie, educational and social reformer and one-half of withdrawn simplicity.

"Can you be a misanthrope and still love or enjoy some individuals? How about a compassionate misanthrope?"

The intense and introspective correspondence was with John Peavoy, an equally smart classmate from Clinton's native Illinois, with whom she had formed a strong, if not particularly close, intellectual bond before they both headed to separate east coast universities. Their lives quickly diverged . . . his on to an academic path, where he now toils in obscurity as an English professor at Scripps College, a small women's school in southern California. The 30 letters, though, reflect their common explorations of a new life away from the influences of home, over a four-year period at the end of the '60s.

"They are windows into a time and a place and a journey of self-discovery, " Peavoy told the New York Times. "This was what college students did before Facebook."

The real surprise about the correspondence is that it reveals an undercurrent of self-doubt even as the civic-minded Hillary Rodham was pursuing a life in student activism, first in the Republican tradition she inherited from a bullying father, and soon in the Democratic party.

In a letter written in the winter of her second year, she confesses her own despair, describing a "February depression". She catalogues a long, paralysed morning skipping classes, languishing in bed, hating herself. "Random thinking usually becomes a process of self-analysis with my ego coming out on the short end, " she writes.

And at one point she demands of herself:

"Define 'happiness' Hillary Rodham, acknowledged agnostic intellectual liberal, emotional conservative."

These are the passages of the correspondence likely to be seized on by the modernday Hillary Clinton's political enemies.

Recent biographies, including one by Carl Bernstein, have made much of a streak of depression that runs through the Rodham family, particularly its menfolk. Hillary Clinton's uncle made a failed suicide attempt . . .

and her two brothers are also prone to melancholy. The letters add to the evidence for what Bernstein described as Clinton's tendency during her college period to fall into "debilitating, self-doubting funks. During the early weeks of her freshman semester, she was so deflated that she called home and confessed failure and an inability to cope."

Worse, Bernstein alleged it was a trait that had never been fully exorcised. The book says her "emotional state'' was "as fragile as it had ever been'' in late 1994 after her close friend Vince Foster had taken his own life, her father had died and the rejection of her healthcare proposals had put the Democrats on the road to a crushing midterm electoral defeat. On the campaign trail this year, her script on universal healthcare includes a line about how she bears "the scars on my back" to prove she has learnt a lot about how not to implement such a policy as president. The scars may be more psychological than physical, according to Bernstein. He wrote: "'I don't know whether she was seeing a doctor or not' . . . she wasn't, so far as is known . . . 'but she was depressed, ' said David Gergen, who was counsel to the president. 'Deeply depressed. I just felt she went into a downward spiral. This was a near-universal view in the White House.'" The insinuation is that a tendency to depression would be a hindrance if faced with another major political setback if she returns to the White House, or if there is some other crisis. In what is certain to be a mud-slinging political contest if Clinton wins the Democratic nomination, these sorts of insinuations will surely bubble to the surface, even if they are never mentioned by the formal Republican campaign.

For now, though, the Clinton camp is relaxed about the emergence of the youthful correspondence, which Mr Peavoy has kept in his vast collection of documents and memorabilia and recently allowed a New York Times reporter to copy. It should be treated, her campaign staff say, proportionate to the fact that it is 40 years old.

While she mentions one encounter with a "Dartmouth boy" she is mainly disappointed at the calibre of men among her fellow students, who, she says, "know a lot about 'self ' and nothing about 'man'". It wasn't until she was at law school at Yale that she met the charismatic Bill Clinton, who she married in 1975 at the age of 27.

As for the actions of her fellow female students, she tells Peavoy that a junior in her dorm had been caught at her boyfriend's apartment in Cambridge in the early hours, saying: "I don't condone her actions, but I'll defend to expulsion her right to do as she pleases . . . an improvement on Voltaire."

If there is very little sex, there is precisely no drugs and rock 'n' roll. Indeed, she tells how she spent a "miserable weekend" arguing with a friend who believed "acid is the way and what did I have against expanding my conscience".

The publication of the letters is one more distraction, unbalancing Clinton's efforts to shift the focus of the campaign onto issues of policy rather than of personal peccadilloes, character and appearance.

Recently, much of the attention on her has focused on her cleavage, much to the fury of her campaign staff. A Washington Post article after a Democratic candidates' debate dedicated itself to her outfit and a neckline that "sat low on her chest and had a subtle V-shape. The cleavage registered after only a quick glance. . . It was startling to see that small acknowledgment of sexuality and femininity peeking out of the conservative . . .

aesthetically speaking . . . environment of Congress."

The article generated hundreds of outraged calls, emails and letters to the Post . . .

and a rebuke from the Clinton staffer Ann Lewis: "Frankly, focusing on women's bodies instead of their ideas is insulting. It's insulting to every woman who has ever tried to be taken seriously in a business meeting."

Nonetheless, the correspondence with Peavoy shines a light on the formation of her political views . . . and the rejection of the Republicanism of her parents in Park Ridge, Illinois. In particular, she details the constant rows with her father, Hugh, the son of Welsh and English immigrants who ran a small textile business.

"God, I feel so divorced from Park Ridge, parents, home, the entire unreality of middle-class America, " she opines in one letter.

"This all sounds so predictable, but it's true."

The Vietnam War was a significant catalyst and by the end of college she was volunteering on senator Eugene McCarthy's antiwar presidential campaign in New Hampshire.

She drifted soon enough, too, from her friendship with John Peavoy. The pair have not met face-to-face since, bar a highschool reunion evening when Hillary Clinton, by then America's first lady, was a guest of honour.

They did correspond one more time, though . . . only this time it was the machine politician writing. Clinton's political antennae had discerned the existence of the correspondence, which Peavoy had previously shown to a biographer, and she was writing to ask if she could have a copy.

"For all I know she's mad at me for keeping the letters, " Peavoy told the New York Times, as he highlighted a neat irony in one of the letters.

"Don't begrudge me my mercenary interest, " she wrote, but she was going to keep his correspondence