Anna Letitia Barbauld was, suggests her biographer William McCarthy, nothing less than the voice of the late 18th century, responsible for crafting its chief thoughts and setting its tone and temper. In a string of essays and poems, she spoke truth to power in a way no one else managed, not even Mary Wollstonecraft, whose name remains resonant while Barbauld's has faded.
The reasons why some names stick and others disappear are complex - to do with fashion, gender, attracting a good biographer, and the bad luck of a house fire in which important sources go up in smoke. In Barbauld's case a mixture of several bad breaks means her name is virtually unknown. The most likely reason, thinks McCarthy, is that the younger generation of Romantic poets was extravagantly nasty to her. By the time Wordsworth and Coleridge were climbing to their prime they were desperate to shrug Barbauld off as a fussy old biddy whose rules about rhyme represented everything that needed to be blasted away. And yet, as these formerly angry young men swung to the right in the frightening years after the French revolution, her continuing engagement with progressive politics began to seem dangerously radical. She was simultaneously behind and ahead of her time - a tricky spot if you're hoping to go down in history.
McCarthy's recuperative biography is almost 800 pages long and 20 years in the making. Usually, these two facts would guarantee a book that is lumbering and worthy, unable to see the wood for the trees. Occasionally, though, a biography of such heft turns out to be a small miracle, a window not just into a life but the whole world that made it. This is what he has achieved in a thrilling, brilliant book. Deeply familiar with Barbauld's work (he is the co-editor of her collected poetry), he manages to integrate close readings of her essays and verse into a life story laid out with sympathy and style. The result is a masterclass in how to write literary biography, a sub-genre that desperately needs such acts of shining confidence if it is to find its pulse again.
Barbauld was born in 1743 into provincial dissent, that cradle of so many key voices of the Enlightenment. Her father taught first at a school and then an academy, coaching lads whose refusal to swear to the 39 articles meant they were barred from the ancient universities. Brought up alongside boys, including her adored younger brother John, Anna Letitia Aikin acquired the intellectual toolbox of a modern young man. There was Latin and Greek, but also modern languages and plenty of science. Most important, she was required to think about politics. Coming to maturity at the end of Britain's seven-year war with France, Russia and Austria, she was brought up against the unpleasant fact that her own country had used war to forge the foundations of an overseas empire. Was it "her" country, anyway? Dissenters might be obliged to pay taxes like everyone else, but they were unable to acquire a seat at Westminster from which to argue about where their money went. By virtue of both her gender and faith, she was doubly barred from citizenship.
No wonder, then, that her early published work fought unfairness wherever it was found. There was a long narrative poem about Corsican independence, an unlikely subject for a teenage girl from Lancashire. Closer to home, though no less charged, was "The Mouse's Petition", verses written by a laboratory animal begging its freedom from Joseph Priestley, the pioneering chemist who was a colleague of her father's. It sounds twee, but behind the tripping rhyme lay a deeply serious point: by what right can one creature ever hold power over another? Years later Barbauld was to write one of her most powerful poems on the shameful occasion in 1791 when Westminster refused to abolish the slave trade.
Long before that moment, though, she had made the crucial decision of her life, the one that ruined everything. In 1774 she pleaded with her parents to be allowed to marry Rochemont Barbauld, an odd man six years her junior whose Frenchness was offset by his impeccable Protestantism. At first the young couple replicated the life of her parents, setting up a boys' school in Suffolk where Anna Letitia busied herself in writing highly successful educational books and worrying about other people's children (she was to have none of her own). In time, though, her husband's eccentricities hardened into something that sounds like a combination of manic depression and obsessive compulsive disorder. He often spent the whole day in the bath, liked running backwards and forwards over thresholds, and spent fortunes he didn't have. It all came to a violent conclusion in 1808 when he took a knife to Anna Letitia, who escaped by jumping through a window. Following their separation, the unhappy man drowned himself.
Instead of kicking over rational restraint, Anna Letitia seems to have retreated further into it. Her armour of choice was stoicism, and she spent her life cultivating a serene smile while resolving not to complain about her ghastly personal circumstances. It was this "passionlessness" that so bothered the Romantics, who put it about that her lack of enthusiasm in bed had sent poor Mr Barbauld to his watery grave.
Despite this concerted attempt to talk her down, what she said and did still mattered in the new century. So when, in 1812, she published a poem that pleased no one, the result was a national scandal. "1811" is a clear-eyed look at the horror and absurdity of fighting the French, the very people whose recent revolution had drawn such admiration from Britain's liberal intelligentsia. While many of those people had rushed to abjure their previous enthusiasm for liberté, égalité and fraternité, the elderly Anna Letitia still thrilled to the possibility that the world was about to be remade in a fairer way. Her despair at realising that, on this occasion, the outcome was the usual one of bloodshed spilled out into verse that struck even old friends and allies as gloomy and unpatriotic. While her intention had been to preserve the Enlightenment's precious gains, to the rest of the world it appeared that she was doing what dissenters always did - sticking to the sidelines while coming over all preachy.
She lived the second part of her long life in north London opposite the brother who had acted in many ways as her real life partner. John Aikin had published her work in his Monthly Magazine, chivvied her for new material, and even given her a child, his son Charles, whom she unofficially adopted. Sensible and pragmatic though all this sounds, it's clear that behind the fixed smile Barbauld spent a lot of time wrestling with the usual writerly demons. On going through her things post-mortem, her niece and first biographer, Lucy Aikin, discovered trunks full of abandoned and scratched-through drafts of verses and essays that had never been allowed to see the light of day.
McCarthy does not bother to pretend that he feels anything other than great admiration for Barbauld, whose calm approach to calling powerful people to account he feels we need now more than ever. Yet in making Barbauld's life and work resonate, he manages to avoid those clunking analogies that have done so much to spoil biographical writing in recent years. So, for instance, when he draws attention to certain generic resemblances between an early chiding poem of Barbauld's addressed to her father and Sylvia Plath's brutal "Daddy", he is not suggesting a crude equivalence so much as a series of telling echoes. Likewise, when he draws Barbauld's work into relation with Virginia Woolf's, he is not making one woman writer stand in for another so much as weaving a web of connections between them. As a result, Barbauld is allowed to be interesting because she remains resolutely of her time as well, implicitly, of ours. It is an admirable approach to writing the biography of a forgotten life, and one that should be savoured.
• Kathryn Hughes's The Short Life and Long Times of Mrs Beeton is published by Harper Perennial.
