NEW YORK• Sometimes CNN anchor Anderson Cooper imagines himself as the Thomas Cromwell to his mother's Henry VIII, the voice of reason - the tether - to her buoyant impulsiveness. And sometimes he pictures Gloria Vanderbilt, who has been in the public eye since her birth 92 years ago, as an emissary from a distant star, marooned on this planet and trying to make sense of it all.

"I always viewed my role as helping her navigate this time and place," Cooper said recently.

But in the documentary of her life, Nothing Left Unsaid, airing on HBO on Saturday, with him as his mother's interlocutor, and in the epistolary memoir the two have made together, The Rainbow Comes And Goes: A Mother And Son On Life, Love, And Loss, out tomorrow from Harper, what instead unfurls are the ways in which this family of two has survived unthinkable losses.

There was the death of his father when Cooper was just 10 and the suicide of his brother Carter, at 23, a decade later, as Vanderbilt watched her son's hands slip from the terrace of their apartment in Gracie Square.

In that same decade, Vanderbilt would make a fortune to rival that of her forebear, Cornelius Vanderbilt, from blue jeans emblazoned with her name and then lose it all when her psychiatrist and lawyer colluded to defraud her of her many lucrative licences.

And yet, Cooper said: "She has this enduring optimism and this sense that the next great love or the next great adventure is just around the corner and she's about to embark on it."

The other day, Vanderbilt brandished her familiar U-shaped grin and her Old World accent, padding about her jewel-box Beekman Place apartment in bare feet.

"The phone can ring and your life can change in a blink," she said. "I also believe you sort of attract what you want, what you're looking for and I think that one must always be in love. To be in love with a person is, of course, ideal, but you can be in love with a flower, a tree, an idea.

"Just waking up in the morning, you know. It's an attitude, an attitude of romantic readiness," she concluded firmly, quoting F. Scott Fitzgerald. "We have to have that."

Vanderbilt, whose father died when she was 15 months old, has been making headlines since her birth. In 1934, the tabloids called her The Poor Little Rich Girl.

That was the year of the bitter custody battle between her aunt Gertrude Whitney and her beautiful, too young, hapless mother Gloria Morgan Vanderbilt, who loved parties and the allowance that accrued to her from her daughter's trust fund.

She made headlines, too, for her storied romances - to Howard Hughes and Frank Sinatra, among many others - and her four marriages, the first, when she was just 17, to an abusive Hollywood agent rumoured to have murdered his first wife.

Vanderbilt largely raised herself, a kind of emotional orphan careening from marriage to marriage before finding happiness with Wyatt Cooper, Anderson Cooper's father, a screenwriter and actor from Mississippi.

"Wait a minute," Cooper writes in The Rainbow Comes And Goes of his mother's first marriage. "You started dating a guy who was a gambler and rumoured to have killed someone? That's not usually the kind of information people put in their Tinder bio to attract dates. Didn't you think that was somebody you should probably stay away from?"

Recalling that exchange, Vanderbilt said: "Of course, you always think you can fix things. You always think you're the one who can."

In many of her eight books, a body of work that includes four memoirs, a book of poetry and an erotic novel, published when she was 85, she continued that interrogation.

Of the erotic novel, Obsession, she said: "That was so much fun. It was almost as if somebody else wrote it and it just sort of fell on the page. When I recorded the audiobook, though, I thought: 'What have I done? Poor Anderson!'"

Clearly, Cooper's inheritance from his mother is not tragedy nor money, as he and his brother were taught at a young age there was no pot of gold for them - though he and she share the same steely work ethic - it is resilience, made springier by a sense of humour.

Both the documentary, directed by Liz Garbus, and the memoir, which is a series of e-mails between mother and son, have Cooper investigating the emotional landscape of his mother's life and, in so doing, examining his own.

They were a year into the documentary when Vanderbilt fell ill with a serious respiratory infection. She did not tell her son just how serious it was and he left town on an assignment, never learning until his return that she had been hospitalised. He was deeply rattled and rued his reflexive impulse to put his work first and view any intrusion as an inconvenience.

On her 91st birthday, they began "a new kind of conversation", as he writes, by e-mail, which Vanderbilt takes up with characteristic enthusiasm. It is a frank and tender undertaking.

In one exchange, Vanderbilt recalled her son coming out to her when he was 21 and being stricken with guilt about a derogatory comment she had once made, that she would feel she had failed as a parent if her child was gay.

As it happened, Cooper had no memory of the incident; instead, he recalled only the positive way she had described a gay couple when he was growing up. "I rejoice that you're gay," she writes her son.

Mother and son concluded their e-mails to each other just before Vanderbilt's 92nd birthday in February. Cooper asks how she is feeling about death, while noting that her funeral plans have always been very detailed.

Vanderbilt does share a few of her instructions: If in a church, how about St James'? If an open coffin, she would like to be dressed in a Fortuny gown; Cooper can pick the colour and they are in the cedar closet in her apartment.

Do not have the funeral cosmeticians do her face. Please ask Judy Collins to sing Amazing Grace. And as is her way, she cheers for her son, exhorting him to put aside his pessimism. "Excelsior!" she writes.

For her part, Vanderbilt is sanguine about her own mortality. She quotes Woody Allen, who was once asked whether he would like to live on in the hearts of people after his death and replied: "I would prefer to live on in my apartment."

NEW YORK TIMES