UNSENTIMENTAL JOURNEY

By Richard Stengel

As host of the crowded cocktail party that is his memoir, Gore Vidal is mostly on his best behavior. He seldom scandalizes his guests and rarely flings a martini into anyone's face. Courtly but gossipy, chummy but not overfamiliar, he proudly points out all the notables he has managed to attract to his soirae. Yet, while there is a good deal of pleasurable ogling to be had, Vidal's book is the sort of grand, teeming affair that leaves you feeling vaguely unsatisfied, as though you are not quite sure why he invited you in the first place.

Vidal turns 70 this month, a fitting time for a man of letters to turn his hand to recollections. But in Palimpsest (Random House; 438 pages; $27.50), he proves a reluctant memoirist. Elsewhere he has confessed that he only embarked on this book in order to stay a step ahead of two biographers. For Vidal the resurrection of his early life (the story ends when he is 39) seems to be an irksome enterprise, and the book reads that way.

Vidal is a first-rate essayist, one of America's finest, though a rather more pedestrian novelist and playwright. His memoir lacks the sharp, confident voice of his essays, while the characters, like those in his novels and plays, often come across as wooden and two dimensional. He complains over and over to the reader of his frayed memory, his disinclination to look backward, his lack of a diary (he relies altogether too much on other people's memoirs instead). As a result, Palimpsest has a kind of haphazard feel, with the present frequently intruding upon the past in a way that distracts from his narrative. (''The editor of the [New York Times] editorial page just rang up; he will come to lunch on Monday.'')

Vidal is snobby about his roots. He was raised in prewar Washington in the seigneurial home of his grandfather Thomas Pryor Gore, the blind Senator from Oklahoma (Vice President Al Gore is his cousin). Vidal's mother was a histrionic alcoholic, so early on he retreated into the world of books and language. He attended the exclusive St. Albans prep school and served as first mate on a supply ship during World War II, after which, at age 20, he published his first novel, Williwaw.

The handsome wunderkind was taken up by the literary powers in New York City, and his career seemed set to soar. But Vidal tells us that his third novel, The City and the Pillar, published in the unenlightened '40s and featuring an overtly homosexual love story, alienated the literary establishment and set him apart as a refugee in his own land. Later we follow him into the bright worlds of television and Hollywood, until he eventually takes refuge in the Old World of Ravello, in Italy, where he has lived for the past 30 years.

Curiously, for a man who prides himself on his unsentimentality, Vidal shades his entire story with the romantic memory of a love affair he had with a classmate at St. Albans. He suggests that blond, sunny, athletic Jimmie Trimble, who died in a foxhole in Iwo Jima, was his Rosebud, his one and only, his Platonic other half. As tender as he is about Trimble, so is he icy about the rest of his romantic attachments (he matter-of-factly states that he'd had 1,000 sexual liaisons by the time he was 25), as well as about most of his family and friends, nearly all of whom seem to disappoint him.

The characters flit on- and offstage like cameos. Here is a good-natured Allen Ginsberg, a self-absorbed Anais Nin, a pathologically untruthful Truman Capote, an endearing Tennessee Williams (who, during lunch with Senator John Kennedy in Palm Beach, Florida, tells Vidal that their host has a great butt), and a rather mawkish Jack Kerouac, with whom Vidal has a brief affair. (No man is a hero to his Vidal--and every man, the author insinuates, harbors homoeroticism within him.)

The character who is most alive--and drawn most acidly--is Jacqueline Bouvier Kennedy, who has the same stepfather as Vidal, Hugh Auchincloss. Vidal introduces the young Jackie in a scene in which she is showing his stepsister how to douche after sex. He depicts Jackie as a tough and consummately selfish woman who loves two things, money and publicity--the former more than the latter. On a night out with Vidal in Provincetown, Massachusetts, in the 1960s, she appears sly and humorous, a girl who wants to kick up her heels. At one point she begs Vidal to tell her how she can become an actress. Jackie was unconcerned about her husband's infidelities, says Vidal (he refers to J.F.K. as "the President-erect"), and suggests she was aware of his inclinations from the start.

Palimpsest is enjoyable as a kind of highbrow gossip column (the famous names could be in boldface), but it lacks the analytical substance that one has come to expect from its author. In a lovely passage, Vidal says he learned from his grandfather ''the ability to detect the false notes in those arias that our shepherds lull their sheep with"--and in fact his story sparkles when he deftly exposes the hypocrisies of Hollywood and Washington. As a writer he is at his best as an uncompromising critic, and at one point turns his sensibility on himself with sharp-eyed accuracy: ''In this text," he writes, "I am not moving toward anything that I am aware of."