he Cuban government has agreed to allow access to a trove of Ernest Hemingway's papers that experts say promises to illuminate the period in which he wrote some of his most significant works.

The collection, deteriorating amid rifles and stuffed African game heads in the basement of Hemingway's home outside Havana, includes 3,000 letters and documents, 3,000 photographs and 9,000 books, many with his musings in the margins ó what one biographer, A. Scott Berg, called a "CAT scan of Hemingway's brain."

Those who helped persuade the Cubans to open the collection, ending an impasse that has frustrated American scholars for 40 years, say they have seen just a small fraction of it, but it already offers hints of Hemingway's creative process: raw fragments of stories scribbled on paper and book jackets, galleys and early drafts of major works, and a poetry anthology in which he circled "No man is an island," the line from John Donne that would serve as the epigraph to "For Whom the Bell Tolls."

There is Hemingway's copy of the screenplay for "The Old Man and the Sea," with his notations. There is a scrap of paper on which he jotted a profanity-laced conversation from World War II, which he apparently planned to use in a story, but then dismissed, writing above it, "too frank." There is the start of an epilogue, later rejected, to "For Whom the Bell Tolls."

The documents also reveal details of Hemingway's personal life: he recorded his weight and blood pressure almost obsessively on the inside cover of his copy of "Wuthering Heights." In a written soliloquy dated June 1, 1953, he agonized about his conflicted feelings for his fourth wife, Mary, wondering whether he should accept her as a scold or "learn not to give a damn about her." He then sent it to her with a cover letter asking her to read it when she got a chance. There are directions to the servants on how to prepare the Hemingways' favorite foods, and in what order to present them. Another note instructs them not to disturb him while he is writing. There are Michelin maps of Spain with names of people he met and restaurants and hotels he visited.

"This really is the last frontier," said Sandra Spanier, a scholar who is involved in the preservation effort, and was chosen last year as the editor of a new collection of Hemingway letters. "We haven't known much about the period he spent in Cuba, except that it was extremely significant and extremely long. This is very promising and not yet fully mapped territory."

Under an agreement with Cuba to be announced in November, American conservators will begin repairing and preserving the materials and scanning and microfilming them. The originals will remain in Cuba, but the electronic collection will be stored in the United States, at the John Fitzgerald Kennedy Library and Museum in Boston, which already has a small Hemingway archive. An inventory of the collection will be available online.

Hemingway spent a third of his life in Cuba, where he lived longer than anywhere else. There, he wrote "The Old Man and the Sea," "For Whom the Bell Tolls," and manuscripts that would be published posthumously, including "A Moveable Feast." He felt such fondness for Cuba that he donated the medal from his 1954 Nobel Prize to the shrine of Virgen de Cobre, the country's patron saint.

Cubans returned the affection with equal intensity. As Patrick Hemingway, the author's son, said in an interview, "I think many Cubans don't realize he wasn't a Cuban." When Hemingway committed suicide in 1961, shortly after the Bay of Pigs invasion, the Cuban government allowed Mary Hemingway to remove 200 pounds of papers, but insisted that most of their home's contents remain untouched. She left the house to the Cubans, who turned it into a museum. The Cuban government has been so protective of its holdings that visitors are allowed only to peer through the windows, where they can see Hemingway's Cinzano bottles and typewriter gathering dust. And no one, not even Cuban scholars, has been allowed to see the documents in the basement.

The agreement to allow the Americans to preserve the documents began with a visit to the museum in January 2001 by Jenny Phillips, a granddaughter of Maxwell Perkins, Hemingway's editor and close friend. Ms. Phillips asked a curator if there might be letters from her grandfather inside, and upon hearing who he was, Ms. Phillips said, the curator invited her and her husband for a special tour of the house, known as Finca Vigia. But they, too, were told they could not enter the basement.

Back home in suburban Boston, the Phillipses went to the Kennedy Library, where Mary Hemingway had donated the papers she removed from Cuba. Stephen Plotkin, a past curator there, told them he knew of the materials and called their deterioration "an archival emergency," but also said that he and other scholars had given up hope of gaining access to them.

The Phillipses sought help from Representative Jim McGovern, a Massachusetts Democrat and longtime advocate of normalizing relations with Cuba. Over the course of a year, Mr. McGovern negotiated with the Cuban government to release and preserve the materials on the condition that they remain in Cuba; the Cubans said they had rebuffed all previous efforts because American scholars had always wanted to take the originals to the United States.

An initial agreement was signed in January, and in March, the Phillipses returned to the house with Ms. Spanier, conservators and Mr. Berg, who had written a biography of Perkins and had studied under Carlos Baker, another Hemingway biographer, at Princeton.

"I think I've read all the biographies of Hemingway and I've never had a a complete sense of him until I smelled this house and saw some of these things," Mr. Berg said. "This is what has been missing on Hemingway, this is the stuff that makes him come alive."

Entering the house's humid, dirt-floored basement, the conservators found many books damaged by insects, and papers fading. But they also found photographs by Robert Capa taken during the Spanish Civil War, 26 letters written by Adriana Ivancich, the young Italian countess who was the subject of Hemingway's infatuation and reportedly the model for the heroine in "Over the River and Into the Trees." There are also other letters, from Ezra Pound and Martha Gellhorn, Hemingway's former wife. There are also lists of provisions he would need for trips on his boat, the Pilar, and instructions from his children's pediatrician jotted inside books.

"Just to have that kind of quotidiana on an important figure is the kind of thing biographers dream of," said Mr. Berg, who won a Pulitzer Prize for his biography of Charles Lindbergh.

Most revealing, he said, was the memo in which Hemingway poured out his conflicts with his wife.

"If that document exists, I imagine others in the same vein do," Mr. Berg said. "And even if they don't, even if that is unique, it suggests a whole kind of dialogue between Ernest and Mary Hemingway that I don't think we knew about, a whole level of pain and candor I have not seen anywhere else."

In one folder, Hemingway had saved newspaper articles about his presumed ó and greatly exaggerated ó death in a plane crash in Africa in 1954. Another folder is filled with 1925 book reviews of "In Our Time."

"Just seeing what he saved is an interesting gauge of the things he valued," Ms. Spanier said.

While Hemingway has been the subject of endless study ó not to mention the inspiration for a licensed line of furniture ó his 21 years in Cuba are the least understood period of his life, scholars say. Mr. Berg said Mr. Baker never visited Cuba. In Michael Reynolds's five-volume biography of Hemingway, there are three volumes covering the first 30 years of his life, and only one covering the last 21.

"We don't have the depth to write about that period," Ms. Spanier said.

The curators at the Finca, she added, had taken great care to preserve the documents despite a lack of resources. There was a trunk stenciled "Tropicana," filled with letters; a curator begged for it from the nightclub of the same name because she was worried about the effect of the temperature changes on the documents. Another curator, finding the kind of acid-free paper she needed to preserve the documents in a shoebox, went to a shoe factory to ask for more of it.

"If something isn't done, it will simply deteriorate," Patrick Hemingway said of the collection.

Earlier this month, the Rockefeller Foundation granted the conservators $75,000 to pay for the initial preservation, and Mr. McGovern said he hoped to raise an additional $25,000 privately.