THE POTOMAC RIVER, dazzling and serene in the fall sunlight, seemed to lap gently against Spence's Point, a wooded haven two hours from Washington, in Westmoreland County, Virginia. But so fierce is the river's erosive force that a previous house at the point "fell into the river quite a while ago," Elizabeth Holdridge Dos Passos recalled recently.

Mrs. Dos Passos -- or "Miss Betty," as her family and neighbors know her -- was seated next to a window overlooking the 175-foot expanse of lawn that sweeps to the water from the electric brick-and-glass facade of her 13-room house. The lawn was covered with chestnuts, shed by a tree planted by her husband, John Dos Passos. Other souvenirs of Dos Passos are the five magnolia trees on the lawn, the brick walks across it, the squat crepe myrtle, its leaves an October orange, and the creosoted jetties that prevent this house from falling into the river like its predecessor.

The house was built in 1806; beginning in the 1940's, Dos Passos remodeled and expanded it. A decade after his death, Spence's Point survives in a kind of austere glory -- its blend of old and new architecture an apt reminder of one of America's leading modernists who began his career protesting the Sacco-Vanzetti trials and ended it as a conservative landowner whose habits and opinions resembled those of the wealthy father who first acquired the Westmoreland estate.

Spence's Point is a working farm of 1,665 acres -- the remains of 7,000 acres bought in 1885 by John R. Dos Passos, the flamboyant corporate lawyer who assembled the Sugar Trust, wrote impassioned defenses of the rights of the wealthy classes, and fathered an illegitimate son. Jack Madison eventually became John Dos Passos, "Dos" to his literary friends and "Mr. Jack" to his friends in the county. As during the writer's life, a local farmer leases the land for corn, soybeans and wheat. At 70, Elizabeth Dos Passos manages the affairs of the farm and takes care of the house, as well as the enormous literary estate Dos Passos left behind. "My husband didn't have an official literary executor," she explained. "As near as can be, I'm it."

She is a tall woman, whose reserved, even grave, manner can yield in a moment to uninhibited laughter at some memory of the great days she spent with Dos. Showing a visitor across the lawn, she retains a torch of the feline good looks that once led a Bahamian fisherman to recall her as "the prettiest white woman I've ever seen."

Their 21-year marriage had its beginning in Dos Passos' work. In 1949, they renewed a distant acquaintance at a Manhattan brunch. She was 40, he was 53. His beloved first wife, Katy, had been killed the year before, in a hideous car crash with Dos Passos at the wheel. Elizabeth's husband, Desmond, had died in a car accident in 1946.

"Things began to mesh," she recalls. He complained to her that he could not get started on a series of articles he had promised to write for General Mills' employee magazine. Elizabeth, who was with Readers Digest , suggested they work together over the coming Memorial Day weekend. She was then living in Mt. Kisco; he rented a sitting room in a Manhattan Hotel. "So I trundled in on the train and trundled out again at night," she said. "At the end of the time, it was finshed. Very soon after that he popped the question. We didn't know each other very well, but we knew we could work together."

The next year, she gave birth to a daughter, Lucy, making Dos Passos a first-time father at the age of 57. They decied to put Lucy and her older half-brother, Christopher Holdridge, in private schools in Baltimore. During the week, the family lived in the Mount Washington neighborhood; on weekends, they returned to Spence's Point.

Wherever he was, Dos Passos was an indefatigable worker. Elizabeth Dos Passos has preserved his study much as it was diring his life. On one wall is a colorful headdress presented to them while on a visit to "a tributary of the Amazon." On another are two of the hundreds of watercolors he painted all his life: one of Mendenhall Glacier in Alaska, another of the South Pacific, where he went as a war correspondent during World War II. There are also four -- count them -- desks. As dos Passos grew bored or stiff at one, he would move to another. He worked four or five hours a day, six days a week -- seven if he was facing a deadline. "This business of waiting for an inspiration was strictly out," she said. "Some days he would accomplish quite a lot, some days very little -- but he tried."

Indeed, in the 21 years of their marriage, Dos Passos completed 18 books -- a dizzying blend of fiction, history, reportage and polemic which represents only a small part of his life's work.

The size of this body of writing -- its scope, its idiosyncratic subject matter, its sheer unwieldiness -- is one important reason why Dos Passos' reputation remains unfocused and elusive today. Indeed the years at Spence's Point were a time of literary isolation for a writer who had once been the darling of the New York critics. Dos Passos and Ernest Hemingway, once close friends, had begun falling out in 1937. A fitful correspondence continued, until one day Elizabeth brought in the mail. "After a few minutes I heard a kind of a rumbling in the other room," she said. "He came in and threw me a letter in Hem's handwriting. It said something about it's good for an old Portuguese to marry a young wife.' He didn't like that and I think there was no correspondence after that. They were so thoroughly out of step by then."

Edmund Wilson remained a close friend, despite bitter disagreement with Dos Passos' conservative politics. In his biography of Dos Passos, Townsend Ludington reports favorably on Wilson's role as confidant, critic, advisor, and foil in the last years of Dos Passos' life. Domestically, however, "Bunny" Wilson played a different role when he and his wife Elena made their only visit to Spence's Point. "We tried to entertain them in the best way we could," Elizabeth Dos Passos recalled. "But Bunny Wilson was not in the least interested in farming -- even from a poetic point of view. I think they were here two nights; it was a long time, I can assure you.

"By this time, Bunny had covinced Elena that she was unable to drive. She'd driven all her adult life, and never had any accidents, but that was the way his mind worked. So they were driven down by Mr. Peck, the only taxi driver in Wellfleet, Massachusetts.

"Mr. Peck was a correct New Englander, always wore a coat and tie and used good grammar, and we just assumed that he would have his meals with us. Oh, no! The great proletarian Edmund Wilson wouldn't listen to that! Oh, it was terrible! In those days it was very hard to find a place to eat anywhere around here, so I had to bring him trays. It was really awfully painful.

"The last night they were here, Bunny lashed out at Dos about something that he had written or hadn't. Elena and I tried to cool it, but it didn't work very well, and Dos didn't want to lash back as he would have if Bunny hadn't been a guest. We were glad to see them go."

Perhaps because of his isolation and his extreme conservatism in later life, Dos Passos' once-formidable reputation has suffered an undeserved eclipse. Studies of "Papa," "Bunny," and "Scott" abound, but almost nothing is said about their great contemporary. "Dos." His tremendous and continuing influence on American literature -- he has left his mark on writers as diverse as William Faulkner, Norman Mailer, Robert A. Heinlein and E. L. Doctorow -- remains a well-kept secret. Perhaps the Ludington biography -- which Elizabeth Dos Passos authorized and read in typescript -- will help set the record straight. If not, there are two more biographies projected, and CBS has optioned Dos Passos' greatest work, the U.S.A. trilogy, for possible TV adaptation.

"Judging from the correspondence I get and the interest of young people in his work, I think the graph is going up -- and rather rapidly," Elizabeth Dos Passos said. "You know, Scott Fitzgerald almost went into total eclipse for a while, and then suddenly he was everywhere! Everything you opened had something about Scott Fitzgerald. I don't think it will be that way with Dos, but I think there's a very definite rise in the graph."