BOOK REVIEW : Feelings of Passion for Sweetness of Life : AMONG THE PORCUPINES <i> Carol Matthau</i> ; Turtle Bay Books $23, 302 pages

If this book were a dessert, it would have a meringue shell and whipped-cream topping. Carol Matthau’s style is light and sweet, although from time to time startlingly earthy.

Now married to the Oscar-winning actor Walter Matthau, Carol used to be married to the Pulitzer-winning playwright William Saroyan. In her own right, she has long been one of those beautiful and singular women people talk about and say memorable things to. At dinner for 12 chez Norton Simon, she was the woman to whom Cary Grant confessed, pointing in a tasteful way at the young man across from him who happened to be Warren Beatty: “I used to be him.”

Saroyan saw Carol, whom he married when she was 17 and he 34, as a perfectly born and bred Fifth Avenue debutante. In fact she was the child of an affair her mother had at 16. When her mother married another man and became pregnant again, her new husband pointed at Carol and said, “Now we can put that one up for adoption.”

Her mother dumped him, worked in a hat factory and boarded Carol out in foster homes. Carol was retrieved when her mother married Charles Marcus, the kindly aviation executive everyone needs as a stepfather, and they moved into an 18-room duplex.

Her first connection to Saroyan, a writer she thought was too famous not to be dead, was a part in a friend’s college production of a Saroyan play. She had one line: “No talking in the public library.” But the line in the play that she really loved was: “He knew the truth and was looking for something better.”

After attending a wedding in California, Carol and her mother hung around Hollywood. “All I wondered about was what to wear,” she writes. “It was wonderful not to have any depth or sensitivity, just to go with the wind.” She wafted into the arms of Saroyan, with the aid of her mother’s friend, band leader Artie Shaw. Carol was 16, Saroyan 33.

At a literary party with Saroyan, she encountered three women side by side on a love seat; they turned out to be Edith Sitwell, Baroness Karen Blixen and Marianne Moore. What are you doing with this child?, they asked, and Saroyan said it was OK, he was going to marry her. The baroness, a.k.a. Isak Dinesen, shooed Saroyan away and gave Carol this advice: “Do anything but marry. Sleep with someone else. Sleep with someone wonderful.”

It probably occurred to Carol Matthau in a late draft of “Among the Porcupines” that her stories of conversations with Cary Grant, Isak Dinesen, Marilyn Monroe, Greta Garbo and Truman Capote--not to mention love affairs with James Agee and Kenneth Tynan--might give her the appearance of a shallow and insensitive name-dropper to the non-famous people who would read her book.

Whatever the motive, she decided to write: “It seems strange that everyone I’m writing about was very famous. I wonder about it, too. Didn’t I ever find anyone interesting who was not famous? Actually, no, I didn’t.” There is, all the same, a very interesting and appealing pharmacist, unnamed, who explains menstruation to her.

Carol and Saroyan married in 1943: She was 17, he was 34. Saroyan, at the time the richest writer in America and almost as famous as Charlie Chaplin, loved his young wife but couldn’t stop bullying her. During one of their many awful fights, he said: “You think because you are beautiful, you can lie and lie and lie and lie every time you open your mouth. That’s all you do--lie. You are a congenital liar.”

Exiled to San Francisco, Carol took care of 3-year-old Aram and infant Lucy while Saroyan’s ferocious mother insulted her in Armenian. Saroyan had a hard time writing and lost a lot of money at a casino and the track, spurred by the delusion that he couldn’t write well when he was well-off. After six years of mutual torture, as Carol writes, “Bill came home one day and told me he was getting a divorce.”

There may be an important omission here. In another part of “Porcupines,” Carol says: “To be honest, I cannot be honest. More of my life is out of this book than in it.” Another story of the first breakup is conveyed in Aram Saroyan’s writing, and yet another in a Saroyan biography by Lawrence Lee and Barry Gifford. When they were first married, Carol objected to anti-Semitic remarks Saroyan made and he answered: “What’s the matter, you’re not Jewish, are you?”

She was too frightened, she told her ex-husband’s biographers, to tell him then that her mother was Jewish.

A few years later, at a concert in Carnegie Hall, a woman recognized Saroyan and introduced herself as a cousin of Carol’s mother. Shocked because the woman looked Jewish, Saroyan confronted Carol with the possibility that she was not the particular sort of blond Fifth Avenue deb he had chosen to marry. Yes, she told him, her mother was Jewish. Saroyan’s first reaction was to say: “How could someone as beautiful as you be Jewish?” His second was to leave. He said it was because she had lied.

When Saroyan returned and begged, Carol remarried him, moved by Charlie Chaplin’s argument. “He is a poet,” Chaplin said. “And when a poet loves you, it is like no other love.” It can be hell, as numerous spouses of poets could have told her. She ended the second marriage because she didn’t like what she was turning into. She observes wisely: “I don’t think marriages break up because of what you do to each other. They break up because of what you must become in order to stay in them.”

Back in New York, Carol had long lunches with Capote, who modeled the heroine of “Breakfast at Tiffany’s” after her, and who advised her to marry rich. But she married for love, another man with a ferocious mother and a passion for gambling. Carol met Walter Matthau when she had a small part and he had a big part in the Broadway comedy, “Will Success Spoil Rock Hunter?” Carol was smitten by his grumpy charm.

In both her marriages, Carol Matthau lived with an artist and a gambler, but she doesn’t make the comparison. Matthau, a lover of Mozart, would have loved to play Salieri in “Amadeus,” but sabotaged his chance at the part in a very interesting way. She doesn’t note Saroyan’s similar need to feel like a failure.

The Matthaus have an intelligent and sensible son, Charlie, who is good about money, perhaps because his father gambles and his mother shops. She chooses to write almost nothing about her first two children, Aram and Lucy. “Among the Porcupines” is a dessert confection. It’s Carol Matthau’s book, and she can leave out the meat course if she wants to. She mentions twice a passage she loves from a Willa Cather novel, “Lucy Gayheart.” After reverses in love, the heroine looks out the window at a snowstorm and realizes she can be in love with, “that old sweetheart, life itself.”

“Among the Porcupines” shows a passion for life, that old sweetheart, without a passionate need to understand it. At some level Matthau probably knows the truth, but has chosen to try to write something better. If Cather hadn’t come to mind, she could have used a line of Saroyan’s: “In the time of your life, live.”