Samuel Johnson: A Life, By David Nokes

In 1777 a delegation of London bookseller-publishers called on the 67-year-old Samuel Johnson with a commission. They wanted the writer, critic, pundit and forefather of the modern literary tribe to embark on a set of biographical prefaces to an edition of the English poets. These biographies, the Lives of the Poets, would become the first monument in the genre to which David Nokes's book belongs, and the last of Johnson's landmark works. Famous since his Dictionary in 1755, a state pensioner (at £300 pa) since 1762, with the limpet-like James Boswell recording (almost) every word and move for the first and finest of celebrity biographies, the melancholic Dr Johnson still deemed his life to have been "a barren waste of time" with "disturbances of the mind very close to madness" – his abiding dread.

Humbly, he took the job, and asked for a meagre 200 guineas (Nokes suggests a multiplication factor of 100 for modern values; I would reckon more). Hardly believing their luck, the publishers swiftly agreed; they would have paid 1500. As deeply steeped in self-reproach as in his beloved cups of tea, Johnson merely responded to this shameless rip-off by remarking "The fact is, not that they have paid me too little, but that I have written too much". All writers know publishers like that.

Born 300 years ago this month, Johnson never falls from fashion or becomes a bore. Apart from his own prodigious gifts, this is because his writing and career embodied, even helped create, the market-dominated landscape of literature, journalism and publishing in England that persists down to this day.

As the lawless early 18th-century "Grub Street" gentrified itself into a half-respectable profession of letters, Johnson's vast bulk of mind and spirit cleared a free commercial space for books, reviews and the debate (and gossip) around them that stood apart from academic and aristocratic hierarchies. His Dictionary, he typically boasts, saw print after nine years of hard graft "with little assistance of the learned, and without any patronage of the great".

If this year's tercentenary fiesta has a bittersweet tang, that may be because a revolution in technology threatens to buy up or shut down the Johnsonian marketplace in thought and talent. Where once professional writers fought for freedom from condescending patricians such as Johnson's bugbear the Earl of Chesterfield, future survival might mean a bow to My Lord Google or His Grace the Duke of Amazon.

For the moment, Johnson's mirror still reflects us in a hundred ways, down to his naughty preference for reviewers who "write chiefly from their own minds" over notices by "duller men" who "are glad to read the books through". Dully, I have done so, and can recommend Nokes. He is a sharp-eyed, close-focused, light-footed chronicler; he moves fast, writes succinctly, quotes richly, speculates rarely and knits the sources into a swift, lively narrative.

"Shaking, twitching, pock-marked, half-blind", Johnson the frail child of a cash-strapped bookseller from Lichfield never shed either his proneness to depression or the form of Tourette's syndrome that made his ungainly form so alarming. This iconic outsider has a perennial appeal for writers (and many non-writers) who dream of making it in London against all the odds and in spite of "the thinnest of hopes".

Yet the hallmark of Nokes's Life is its avoidance of myth and hindsight. He looks behind the grandstanding figure shaped by "competitive repartee". He scrubs the stress, exhaustion, fear and sheer insecurity of Johnson's career clean of the rosy glow of heroic adversity that readers of Boswell tend to see. This Johnson marries "Tetty" Porter, a widow 20 years his senior, for money as much as love. Penniless, he quits Oxford not as a tragic reject (Sam the Obscure) but as an "insubordinate" prodigy who planned a rapid comeback.

Nokes's scrupulous insistence on steering Sam clear of the fog of legend has a downside. Important figures as David Garrick – pupil, friend and future stage superstar – appear abruptly, trailing no clouds of glory but not much explanation either. Averse to contextual clutter, Nokes has a habit of using phrases such as "rabid anti-government Whiggery" before he bothers to spell out what they mean. Admirably keen on drama, colour and well-quoted dialogue, he drops us in the thick of the action, and leaves us to piece together a back-story. Readers might like to refer to David Womersley's Penguin Classics edition of Boswell's Life of Johnson, with its encyclopaedic notes.

In many lights, however, Nokes's Johnson looks as noble and unique as ever. His support over decades as "virtual parent" to the Jamaican freedman Francis Barber – the servant who became his legatee - epitomised a loathing for slavery, and a distrust of colonial arrogance, that came from the heart. Frank elicits a rare purple passage, his Caribbean childhood evoked via a dip into picturesque life-writing in the Ackroyd vein. The prejudice-free humanity of Johnson, a Church-and-King Tory, can still make liberal idealism sound hollow and hypocritical – above all, that of the American revolutionaries: "How is it that we hear the loudest yelps for liberty from the drivers of negroes?"

Johnson's tenderness for the insulted and the injured might have chimed with his own sense of exclusion, but he also deployed a self-critical Anglican piety as a defence against large sensual appetites. Garrick reports asking Johnson to name humanity's greatest pleasure. Uncontroversially, for an 18th- or 21st-century Londoner, he answered: "fucking and the second was drinking". Prayer by prayer, Nokes charts a lonely battle for "moral self-control".

Braiding their letters and journals into a tragi-comic love story, Nokes also traces Johnson's platonic passion for Hester Thrale: the Welsh wife of a wealthy Southwark brewer whose friendship dominated the last 20 years of his life. This tale can never fail, but Nokes does it proud. He presents Hester, "the first of humankind" to Johnson, as the last and most adored in a long line of clever women friends.

Johnson, who lovingly collected waifs and strays, feared abandonment and solitude. And the widowed Hester did abandon him, rushing to marry the musician Gabriel Piozzi months before Johnson's death in December 1784.

Look at the lasting works and you see scorned and snubbed genres built up into dignity and even grandeur: biographies, essays, journals, editions, the Dictionary. Nonentities, human and literary, grow into nobilities. And, even if it expires soon, the lowly scribbling trade that he emboldened with a giant's roar has survived for 250 years. When this sickly baby emerged into the light of Lichfield, the midwife had said, "Here is a brave boy". Yes, a brave boy.