Books: The lad of many parts

The usual perception of James Boswell is of a vain, egotistical, amoral, neurotic, buffoonish exhibitionist, a foil to his mentor Samuel Johnson, who appears as the Socrates of the story - erudite, incisive, wise, humane, dignified, witty. To put it another way, Boswell is forever the Watson to Johnson's Sherlock Holmes, the Sancho Panza to his Don Quixote.

The greatest quality of Peter Martin's impressive revisionist biography is the way it subverts these conventional expectations. He persuades me that Boswell was a better writer than Johnson and had a finer mind. Johnson's reputation is absurdly overblown. He was insanely jealous of all his more gifted contemporaries, and there were many, from Wilkes to Hume. The good doctor did not know how to argue a case, and if Boswell disagreed with him, he lost his temper or sulked. Johnson's idea of conversation was essentially that of the pampered star on a modern chat show. He expected that whatever he said, however fatuous, would be greeted with nods, smiles and laughter.

Where Johnson was riddled with political bigotry (any proposal to narrow the scandalous gap between rich and poor in the 18th century was derided as "levelling down"), misogyny (Martin cites half a dozen shocking examples and suggests that Johnson might have had problems achieving normal orgasm), and racism (with Americans and Scots particularly featuring in his demonology), Boswell was always more alive to nuance, ambiguity and what Keats called "negative capability". Most of all, he was a more complete human being. Maybe at times Martin overdoes this side of Boswell, especially in the meticulous examination of the multitudinous sexual escapades, but he faces his subject's satyriasis with admirable clarity.

Boswell was a writer of genius who wasted much of his talent pursuing a futile career as an advocate in Scotland and a barrister in England. As an advocate he was a highly skilled propagandist for his clients and a courageous, even foolhardy, defence counsel.

Unlike Johnson, who was a trimmer, Boswell was a natural rebel - not a useful characteristic for a lawyer. His zest for life and curiosity about others was inexhaustible. His charm and charisma must have been literally fabulous, for he could win over almost any human being he set his sights on.

Boswell would write to chosen luminaries, asking for an interview and pointing out that he was "of singular merit". Intrigued, the targets would invariably have to meet the boastful young man who penned such words and when they did, they were hooked. Boswell gate-crashed where others feared to tread and successively won the friendship and respect of Rousseau, Voltaire, Paoli, Wilkes, Hume, Lord Kames, Goldsmith and, of course, Johnson. The only literary celebrity to resist the charm was Horace Walpole, possibly because his closet homosexuality could find no common ground with the Scot's rampant heterosexuality.

Boswell wrote thousands of words each day, either in journals or for publication. The sources for his life are probably the most copious for any 18th-century figure, and Martin has mastered them. The snag is that writing a life of Boswell is a kind of Hegelian task, for he was involved in all the main currents of European politics and culture from 1750 to 1790.

Fully to comprehend Boswell, one must not only vanquish the mountain of primary material at Yale and elsewhere but also be expert in the most heterogeneous fields: Rousseau and Voltaire studies, the empiricist philosophy of Berkeley and Hume, 18th-century cabinet government, the Scottish legal system, Corsica, crime and punishment, Jacobitism, the history of the Highlands. It is scarcely a criticism of Martin to say that he sometimes lacks the depth of knowledge to contextualise Boswell properly, but I did find his treatment of the famous tour of the Hebrides with Johnson in 1773-74 let down by a less than complete grasp of the Jacobite dimension. There are many better accounts extent of this jaunt in the Highlands.

On the other hand, there is no aspect of Boswell's life - whether it be his defence of the American colonists against Johnson's imprecations, his morbid liking for public executions, his rivalry with Hester Thrale Piozzi as Johnson's most trusted confidante, his chequered relationship with Henry Dundas (for 30 years effectively the ruler of Scotland), and his troubled family relationships with disapproving father, imbecile brother and long-suffering wife - where Martin does not have valuable insights to convey. He rightly makes Boswell's hypochondria a central theme but does not, in my view, probe deeply enough to uncover the roots of his melancholia. The judgement that Boswell was "like an actor on a stage surrounded by mirrors, each reflecting back at him the multiple aspects of his mind" is disappointingly anodyne. Such a judgement could be passed on almost any interesting human being.

Martin is at his best when dealing with Boswell's prodigious sexual appetite. He even tells us which woman gave him the most pleasure in bed - the dissolute adventuress, forger and perjurer Margaret Caroline Rudd.

The hundreds of women Boswell slept with produced no less than 16 separate bouts of gonorrhoea. Here we surely have the Victor Hugo syndrome, the prolific writer who is also a legendary womaniser.

One vulgar wag said that Boswell was fertile both upstairs and downstairs. His two overriding aims in life were to possess women and compete with gifted men; when he slept with Rousseau's mistress Therese Le Vasseur, he achieved, as it were, the grand slam of making love to a woman allegedly "possessed" by the most original mind of his age.

Johnson may have proved that the pen was mightier than the phallic sword, but in Boswell's case it was a close-run thing.