Saul Bellow Nobel prize-winning writer, hailed as one of the great American novelists of the twentieth century

His work touched on the essence of human existence, the experience of immigrants and Jews, and class and social mobility in twentieth-century America.

The 89-year-old writer, who had been in declining health, died at his home in Massachusetts on Tuesday. His wife Janis, and five-year-old daughter, Naomi, were at his side.

Following three National Book Awards, he won the Pulitzer Prize in 1976 for Humboldt's Gift. That same year Bellow was awarded the Nobel Prize, for his "human understanding and subtle analysis of contemporary culture."

In 2003, the Library of America issued a volume of Bellow's early novels, a rare tribute to a living writer from the non-profit publisher, which was created to preserve the American literary heritage.

"The backbone of twentiethcentury American literature has been provided by two novelists - William Faulkner and Saul Bellow, " fellow writer Philip Roth said.

"Together they are the Melville, Hawthorne and Twain of the twentieth century."

Bellow was the most acclaimed of a generation of Jewish writers who emerged after the Second World War, among them Roth and Bernard Malamud, leading Bellow to joke that he and his two peers were the "Hart, Schaffner and Marx" of literature. To American letters, he brought the immigrant's hustle, the bookworm's brains and the high-minded notions of the born romantic.

In spite, or perhaps because, of all the praise, Bellow also had detractors. Norman Mailer called Augie March a "travelogue for timid intellectuals." Critic Alfred Kazin, a longtime friend who became estranged from Bellow, thought the author had become a "university intellectual" with "contempt for the lower orders." Biographer James Atlas accused Bellow of favouring "subservient women in order to serve his own shaky self-image."

Old-fashioned, but not complacent, he kept writing into his 80s and, hoping to make his work more affordable, had his novella A Theft published as a paperback original in 1989. His recent works included The Actual, a sentimental novella published in 1997, and Ravelstein, a novel published in 2000 which was based on the life of his late friend Allan Bloom, author of The Closing of the American Mind. Also in 2000, Bellow was the subject of Atlas' acclaimed biography.

Bellow had a gift for describing faces, and the author's own looks - snowy hair, aristocratic nose and a space between his front teeth - were familiar from book jackets. His personality was equally distinctive. In Humboldt's Gift, the narrator's childhood sweetheart refers to him as a "good man who's led a cranky life."

He had five wives, three sons and, at age 84, a daughter. He met presidents (Kennedy, Johnson) and movie stars (Marilyn Monroe, Jack Nicholson). He feuded with writers (Truman Capote, Mailer), and helped out writers, notably William Kennedy, on whose behalf he lobbied to get his work published.

"When I first talked about writing with Saul he insisted on the ability to change, to get a serious grip on what was real in your life, " Kennedy said. "He was the twentieth century's literary wizard, who fused the intellect and the imagination in glorious and comic language that we'd never heard before."

After teaching for many years at the University of Chicago, Bellow stunned both the literary and academic world by leaving the city with which he was so deeply associated. In 1993, he accepted a position at Boston University, where he taught a first year class on "young men on the make" in literature.

Like his characters, Bellow's life was an evolution from the unbearable, yet comic passion of the Old World, to the unbearable, yet comic alienation of the NewWorld.

The son of Russian immigrants, he was born Solomon Bellows in Lachine, Quebec, outside Montreal. He dropped the final "s" from his last name and changed his first name to Saul when he began publishing his writing in the 1940s.

The classic Bellow narrator was a self-absorbed intellectual with ideals the author himself seemed to form during the Depression. While he would remember the fear most people had during those years, Bellow found them an exciting and even liberating time.

"There were people going to libraries and reading books, " he told The Associated Press in a 1997 interview. "They were going to libraries because they were trying to keep warm; they had no heat in their houses.

There was a great deal of mental energy in those days, of very appealing sorts. Working stiffs were having ideas."

From the beginning, Bellow was determined to tell a different kind of American story to depart from the tightlipped machismo of Ernest Hemingway.

"Do you have emotions?

Strangle them. To a degree, everyone obeys this code, " Bellow wrote in his debut novel, Dangling Man, published in 1944. While the Hemingway hero keeps his problems to himself, Bellow declared: "I intend to talk about mine."

The Bellow themes were in place, but his prose matured later. As the author himself would acknowledge, his early books were too prim, too careful. Only in 1953, with The Adventures of Augie March, would readers see another Bellow: the funny Bellow, the immigrant Bellow, Bellow the son of a bootlegger.

"Well, Augie March was a sort of Niagara of freedom that poured over me suddenly. I thought of myself as an imperfect writer who needed to perfect himself, perfect his language and style, and all of a sudden that was a suffocating project that I had to break with, " he said.

Augie March and the books that followed - Seize the Day, Henderson the Rain King, Herzog - established him, and perhaps saddled him, as a canonical writer. In each work, Bellow lived up to Augie March's idea of imaginative power, of inventing "a man who can stand before the terrible appearances."

Bellow's men stood before the NewWorld and trembled.

Non-believers amid the worship of machines and money, they shook with existential despair. They did everything from compose letters to dead people in Herzog, to running away to Africa in Henderson the Rain King.

"There is something terribly nervous-making about a modern existence. For one thing, it's all the thinking we have to do and all the judgments we have to make. It's the price of freedom: make the judgments, make the mental calls, " he said.