Declan Moriarty does not own a telephone. He lives in a stone house outside Ballyvaughan, in County Clare, with a dog, a Rayburn stove, and 3,000 books, and when his publisher wanted to reach him last year to say that the manuscript he had posted, unannounced, in a brown envelope, was the best thing she had read in a decade, she had to drive four hours to tell him.

“He made me tea and said, ‘Well, it took long enough,’” recalled Siobhán Breen, the publishing director of Liffey Press, which brought out his first four novels between 1981 and 1992 and which will publish “The Long Field” on Thursday. “Then he asked if I wanted to see the garden.”

Mr. Moriarty, 71, was once the most celebrated Irish novelist of his generation. His second book, “The Tenants,” a study of a Clare farming family during the Economic War of the 1930s, won the main Irish fiction prize in 1984 and was shortlisted for a major British one. His fourth, “Hollow Lane,” was his most ambitious and least loved, and after it appeared in 1992 he stopped publishing. He taught at a secondary school in Ennis until 2010, then retired. He gave no interviews. Rumors circulated that he had written nothing, or had written and burned it, or had become a monk.

“I wrote every day,” he said, sitting at a kitchen table that doubles as his desk, in his first interview in 34 years. “I just did not finish anything I thought was worth your time. There is a great deal of that. Most of it is in the stove.” He was wearing a cardigan with a hole in one elbow and spoke slowly, with long pauses that he did not seem to find uncomfortable.

“The Long Field” is a 260-page novel about a retired schoolteacher in the west of Ireland who inherits a field from a brother he had not spoken to in 40 years and spends a single summer deciding what to do with it. Nothing much happens. A fence is mended. A neighbor’s cattle are moved. A letter is written and not sent. It is, in the view of the half-dozen critics who have read advance copies, a masterpiece, and the kind of book that is only written by someone who has stopped caring whether it is one.

“The early books were trying to prove something,” said Prof. Máire Ní Dhomhnaill of University College Dublin, who has taught Mr. Moriarty’s work for 25 years and had long assumed there would be no more of it. “This one is not trying to do anything. That is why it does everything.”

Mr. Moriarty is not sentimental about his silence. “People would like there to have been a crisis,” he said. “There was no crisis. I was a man who taught English to 15-year-olds and had a book he could not get right. Then one morning in 2023 I could get it right, and 18 months later it was done.” He will not be attending the launch in Dublin. “I have been to Dublin,” he said.

Asked whether there would be another, he looked at the dog for a while. “There is a drawer,” he said. “It is not empty.”