Eugene McCarthy once let it be known that if he were elected president, he thought Barbara Tuchman would make a grand secretary of state, but although the doings of diplomats have always figured in her writing, it is not the job for her.

"No tact, no patience," she explains. "You can't make enemies in a job like that, and I have no capacity to suffer fools."

She thoroughly enjoys the job of understanding human folly and time's passing. There have always been, after all, echoes and oments to be found in the long tread of centuries, and past portents led her to the subject of her present book, "A Distant Mirror."

"Living as we do under the shadow of disaster," she said, "I thought it would be interesting to see what happened in the 14th century, after the experience of the Black Death and all the other catastrophes."

The books that she has written stant at parade attention on the mantlepiece in her daughter's living room where she is speaking: "The Guns of August," "The Proud Tower," "Stillwell and the American Experience in China," "Bible and Sword," "The Zimmerman Telegram."

Two of them (The Guns of August" and "Stillwell") have won her Puliter Prizes, and all of them make it clear that Barbara Tuchman likes her history whole, in all its chaos and laughter and mourning, and that she is not about to force her muse into any theoretical or ideological corsets.

"You have to account for the randomness," she says for "all the silly, absurd, grievous things that people can do." And so it isn't just the great broad rivers of history whose courses the charts, but all its inlets and tide-pools and the marshy meadows in between.

In "A Distant Mirror", she writes about apocalypse and the dread, the tremors that seize a society's collapse, and the pathos that is so often a consequence of human pride. But she writes as well about how crimson and green, being the most expensive colors, were among the most favored for the nascent bourgeoisie, how there was little mother love and absolutely no tea or coffee and how the criers walked through the crowded streets of Paris to announce the dead and call, "Wake you sleepers, pray God to forgive your trespasses; the dead cannot cry; pray for their souls as the bell sounds in the streets," and how "stray dogs howled to hear them."

She delights in the contradictions. "Look at Chaucer," she says, "think of all the gloom and pessimism of his age - here's a person who was right in the middle of it and his view was so compassionate."

Of her own era, which of course, is meant to find its reflection in her distant mirror, she is not so certain. She is 66, and her hair is the color of the steel that lines her character and her carriage. "The people of my generation have lived through an era of collapsed assumptions," she says. "There has been a lot of what you call craziness."

Called on for examples> she steps delicately through the minefields of contemporary controversies. There is, she says, "the whole field of heterosexual and homosexual rights, for instance - well, let's not get into the homosexual part, but the sexual freedom of unmarried men and women - now that's a whole set of changes that, while on the whole it's been good, take some getting used to."

And then, of course there is the rejection of authority "by people with no particularly great qualifications for judgement," and such phenomena as transsexual operations, and "this crazy cult of intimidation," and "the cult of the body" and the turn toward the irrational - "I don't relate to much in modern culture," she says in summation."I'm a rather nervous relic of the 19th century."

It was in that century, she says, that her grandfather made his way supported by certitudes that are backing now. "My grandfather believed in the goodness of America," she said. "That if you worked hard, all would come to you. That quote - "I am the master of my fate. I am the captain of my soul - they believed that. Now it seems the prevading idea is cynical, a sense of events beyond anyone's control."

It was a sense that pervaded the 14th century as well and one that took seven years to document and research and index on notecards. And because she is not, the sort of historian to find the meaning of all it solely in diplomats' decision and generals' tactics, there were quite a lot of notecards that took heed not only of the momentous but the minutize.

"I had headings for everything," she says. "Food, friars, salvation - everything was filed alphabetically and chronologically." New categories would occasionally have to be added "After awhile, I realized that everything I was gathering on the Church was overwhelmingly negative, and so, to balance it out, I started a new heading, and called it "Positive Aspects of the Church.'"

She traveled too, over the great scarred fields of battle and ruin, and over the mountains the Crusaders themselves crossed and to the former domain of Enguerrard de Coucy VII, the protagonist of her narrative, the remnants of whose castle still cling to the high ground overlooking Paris.

She traveled as well to Turkey, where the captive Crusaders were taken after their final defeat at the hands of the sultan. Looking across the Hellespont one day, she realised, as she describes it in her book, that "the prisoners could see the fatal shores of Troy across the straits where the most famous, most foolish, most grievous war of myth or history, the archetype of human bellicosity had been played out. Nothing mean nor great, sorrowful, heroic nor absurd had been missing from that 10 years' catalogue of woe."

The conversation jumps from the folly of Troy to the battle of Crecy to Vietnam - "now look at that war for stupidity and macho," and it is distressingly clear what a bane on man's existence has been his "insistence on personal glory."

She has moved out to the patio. The bane of the day is yet another universal, in this case, the weather - will it rain? Will it be too cool for late summer dresses? Where is one to put the bar?

Tuchman is asked if man's seeming insistence on making the same mistakes over again has made her much of a pessimist. "People are always asking me to draw conclusions," she says."They always want to know if I believe in progress. I don't believe in major moral progress," but she also doesn't think that the tale that history tells is one of "innocence despoiled by corruption." It is instead, the story of "the weakness and fallibility of ordinary men who are dealing in the fates of nations."

Ordinary men have managed to wreak quite a bit of havoc in the fates of nations and the ways and means by which ignorant armies clash by night have figured so often in Tuchman's writings that she is asked why she thinks it is that the race seems so determined to continue in its contentiousness.

The answer is not quite what is expected from this elegant, fine-boned, porcelain women, who seems a bit of a Tory and a terror to boot. "Human affairs, she says, "have always been dominated by men, and I think there is always a certain anxiety bout, if you'll forgive the phrase, getting it up. White a woman can be passive and still accomplish the matter at hand, a man has to prove it every time, and so he creates an image of power and force and macho, as they call it these days."

Whatever they call it these days, whatever the shifts in values and assumptions requested by the present, the past demands objectivity, selections and truth. "You have to give it shape," she says. "You have to give it action. It never gets any easier."

She is talking about the writing of it, but she could have been talking about the living of it just as well.