There are times when you feel he could have been more selective in what is included. Some chapters drag; detailed descriptions of Eliot's long holidays abroad are unnecessary; and Karl faces an uphill struggle with the years of Eliot's life when she was creatively idle or suffering from psychosomatic ailments. But, overall, he has written a fascinating study of this remarkable woman.

George Eliot was born Mary Anne Evans near Nuneaton in the English Midlands in 1819. Her father, Robert Evans, was a typical self-made man who believed devoutly in king, country and the infallibility of the Church of England. Any deviation from the norm shocked him and, at first, his daughter was dutiful. But even at the mediocre schools she attended, Mary Anne (later Marian) and her brilliance could not be ignored. She read widely and voraciously.

Her first act of rebellion came in 1842 when she stopped attending church services. Her father refused to speak to her and threatened to cut her out of his will. They reached a compromise and she went back to church, although she made it plain she no longer believed in formal religion.

Robert Evans never forgave her and when he died in 1849, he only left her a small allowance, even though she alone had nursed him through his long illness.

With meagre resources, she set about reconstructing her life. She travelled to Europe, which for a single woman in those days was unheard of. She became fluent in German, Spanish and Italian and before turning to fiction was to translate the works of a number of important philosophers.

In Nuneaton and Coventry she had built up a small group of fellow independent thinkers who helped with her early development. But it was not until she settled in London, that she met people who were closer to being her intellectual equal.

One of the most important was the man now known as the father of sociology, Herbert Spencer.

She began to write pieces for a journal called Westminster Review and met another contributor, the self-taught scientist, George Henry Lewes. He was already married, although he and his wife Agnes had an 'understanding'. When she had one illegitimate child by his business partner Thornton Leigh Hunt, Lewes was tolerant but by the second one he had had enough.

Lewes and Marian developed a relationship which culminated in them running off to Germany in 1854. Their elopement caused a scandal which led to irrevocable splits with friends and family. Spencer stood by Marian but her brother Isaac cut her off. She was 34 and had still to produce her first work of fiction.

It was only in 1856 that Lewes encouraged her to try writing a novella as they were short of funds. This led to her first success, Scenes of Clerical Life, accepted by the Edinburgh publisher William Blackwood.

Lewes sent the manuscript to Scotland under the pseudonym of George Eliot and it was immediately accepted. Blackwood knew he was reading a major new talent and was impressed that here was a young man who understood his male and female characters with equal prescience.

Most people were taken in by the concealed identity which Marian felt was necessary as she was still considered to be the scarlet woman. She correctly surmised that by the time her true identity became known, the puritanical Blackwood would be unable to ditch her.

While she fooled most people there was one fellow scribe who knew the tricks of the trade too well. Charles Dickens wrote of Scenes: 'If they originated with no woman, I believe that no man ever before had the art of making himself mentally so like a woman since the world began.' After the publication of her first novel, Adam Bede, in 1859, she revealed who she was. Some people were shocked; others found her genius overrode all other considerations.

But success did not mean she was reinstated socially. While Tennyson, Darwin, Browning, Henry James and Thomas Huxley were regular visitors to the home of Eliot and Lewes in London, there were still many fashionable drawing rooms where Lewes alone was welcome.

Marian, now Eliot, never got over being treated like an outcast and it is reflected in her fiction, as was so much of her life.

Insults from social peers and critics wounded her deeply and Lewes tried to protect her from them. She was frequently depressed, yet this seemed to fuel her as a writer rather than impede her progress.

Karl writes: 'She was in her own words a compulsive personality, a condition often linked to general sadness and depression. The reach for perfection would always be disappointed. Her inability to tolerate criticism was associated with her sense of an ideal she knew she could never achieve.' She took the disappointments she experienced and, through her astonishing powers of self-discipline, fashioned them into literature.

'Sadness,' says Karl, 'gave her psychological insight - in effect her voice.' Adam Bede was her transitional novel, the springboard which would launch her to greater things. Like Mill On the Floss, Silas Marner and Romola, it showed the writer negotiating the foothills as she headed towards the summit and her masterpiece Middlemarch.

Eliot began Middlemarch in 1869. She completed it in 1872 and it bears all the hallmarks of her prose at its very best. Rather than looking at a society in turmoil, as Dickens so often did, she concentrated on individuals and their own personal tragedies.

She was 'creating a monument to human behaviour', Karl says, trawling the depths of her own past to find inspiration. In Dorothea Brooke we see a woman accepting the moral rules of 1830s England until she falls in love and, like her creator, is forced to either conform and suppress her feelings or be exiled to the edges of society.

Meanwhile, Karl maintains Casaubon 'represents failure. . . he is that terrified half Eliot was never able to bury'.

Despite the human tragedy, the society remains an ordered one. Eliot exposed hypocrisy in Victorian England but did not advocate radical change.

She was only to write one more novel, Daniel Deronda. While completing it, she began to experience the pains that, unknown to her or the doctors of the day, were the first symptoms of the kidney disease which would finally kill her.

After Lewes died in 1878, Eliot married John Cross, a man 20 years her junior. He offered her the protection from the world Lewes had given her. But she was only to enjoy it for seven months before she died in 1880.

By the time of her death, Eliot was the third most famous woman in England after Queen Victoria and Florence Nightingale. She had known literary and financial success. In one year alone, she earned the modern equivalent of US$500,000.

Yet when she died, that elopement with Lewes could not be forgotten. It was decided not to bury her in Westminster Abbey. Instead she was laid to rest next to Lewes in the unconsecrated (dissenters) portion of Highgate Cemetery.

Eliot was a complex woman. Her best fiction is multi-layered and equally complex. Karl peels away these layers; one of the chief functions of good biographers.

He is at his best when analysing the novels and seeing how the characters and events found parallels in Eliot's own life and were turned into literature by her genius.

Some of the links are obvious but many are not and his painstaking reading of her novels, journals and correspondence result in perceptive analysis gratefully free of academic jargon. But I disagree with Karl's claim that Eliot was the 'voice of the century'. At no point does he offer sufficient evidence to support this assertion. It was a century of such profound changes, it had no single voice.