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John Maynard Keynes really started something in the early 1940s when he tried to change the accepted view of Isaac Newton. Keynes attempted to overturn the concept of Newton as "the first and greatest of the modern age of scientists, a rationalist, one who taught us to think on the lines of cold and untinctured reason". In came Newton "the last of the magicians, the last of the Babylonians and Sumerians, the last great mind which looked out on the visible and intellectual world with the same eyes as those who began to build our intellectual inheritance rather less than 10,000 years ago I the last wonder-child to whom the Magi could do sincere and appropriate homage".

Michael White has clearly stumbled across this Keynsian transmutation with whoops of joy. There was obviously a book in it. Today we carry all the 20th-century baggage of modern scientific activity and attitude. We live in an age where alchemy and chemistry are divorced, as are astrology and astronomy, the dentist's surgery and the barber's shop. But it was not always thus. In Newton's time, mental peregrinations over a vast range of scientific topics were commonplace among scholars. Newton's own flittings between mathematics, alchemy, physics, astronomy and theology were quite unremarkable.

And the pace of change was so much slower then. One generation's science and engineering was very similar to the next. So people did not expect to make huge advances, and a rather complacent tenet of intellectual life was that some things will always be unknowable. This, coupled with Newton's rather occultist and esoteric approach, easily led him to believe not only that the universe was a cryptogram sent by the Almighty but also that the ancient "magi" had once held the key to all knowledge, and that this had been lost. So looking back was just as important as looking forward.

Newton stood out from the academic crowd by being a genius: and geniuses are very peculiar. Also, he was profoundly neurotic. His Cambridge days amply revealed his fearful, cautious and suspicious temperament. He certainly tried to shrink from the world, but he had an almost paralysing fear of exposing his thoughts, beliefs and discoveries to the inspection and criticism of others. Only two things forced Newton to publish anything. One was extreme pressure from friends. The other was the fear that someone else might catch up with him. Newton maintained an obsessive belief in his own uniqueness. He was horrified by the idea that others might independently acquire the same insights and accomplish the same breakthroughs.

But behind this conflict between introversion and excessive competition was a mental gymnast of astounding ability, a man who could concentrate on a problem for days on end, and who refused to turn away from it until it had succumbed to a solution.

What is also intriguing about Newton is that he had two completely different careers. In middle age he dropped out of academic life and became an extremely successful civil servant. All academics wonder why, and how, and if they dare to. The "why" is easy. He never enjoyed teaching, and cared little for students. In fact, far from trying to popularise his subject by teaching it properly, Newton took the very opposite stance. His masterpiece, Principia, was deliberately obscure and written in classical Latin so that only the intellectual elite could read it. His overriding concern was for his own research. And even here, instead of basking in his huge successes in the fields of astronomy and physics it is possible that the pursuit of the impossible goals of alchemy damaged him intellectually.

Maybe he was pleasantly surprised by his enjoyment of university "politics". Newton sat on a committee that opposed the admission of Roman Catholics to Cambridge. Here he acquired a taste for official responsibility and realised that he had a great ability for marshalling arguments and taking a forceful lead in representing strongly held beliefs. His status beyond the scientific community blossomed. Aware that his best scientific work lay behind him, he jumped at the chance of moving into new fields.

White has provided the reader with a rumbustious, galloping tale. Isaac Newton: The Last Sorcerer is one of those books that is extremely hard to put down. Every page reveals a diverting aspect of Newton's life. White has clearly studied his subject long and hard. But instead of going for the dry, dusty approach to scientific biography we are treated to a middle-of-the-road, "tabloid journalistic" write-up. The reader is constantly titillated by imagined scurrilous headlines.

Why did Newton love the colour crimson? Did he really die a virgin and never see the sea? Just how friendly was he with John Wickins (his room-mate at Trinity College, Cambridge for 20 years) and Nicholas Fatio de Duillier (a Swiss mathematician 22 years younger than Newton)? Was he a suppressed homosexual? What about his relationship with his beautiful, gregarious, intelligent, excitable and flirtatious half-niece Catherine Barton? How could such a devout puritan like Newton condone the fact that his afore-mentioned niece (and housekeeper in London) and his best friend (Charles Montague, Baron Halifax) were lovers? Did Newton really have a mental breakdown in September 1693, or did he suffer from mercury poisoning? How could an emotionally desiccated, obsessive academic convert himself into a first-class business manager of the Royal Mint? Was his alchemy really a clue to the inverse square law or did his attempts at manipulating nature train him to manipulate people? Is it that easy to sublimate scientific ambition in social and political success?

This book provides an insight into a host of "characters" all rolled into a single person. There is the son of an illiterate Lincolnshire farmer, who turned out to be so incompetent at farm management that he was sent to Cambridge to get him out of the way. There is the archetypal absent-minded professor and author of the Principia, the greatest single book in the history of physical science. There is the alchemist and biblical chronologist who did a bit of science in his spare time. There is the 50-year-old who converted himself from being a reclusive don in a provincial fenland town into a successful socialite, an efficient and influential administrator, and a shrewd Member of Parliament with a house in St James's. There is the commoner who received a knighthood at 62 and was buried in Westminster Abbey.

All in all, Newton's life and work stand both as a high point in a fertile age, and as a source of eternal fascination. This book reveals why.

David Hughes is reader in astronomy, University of Sheffield.