Dante by Barbara Reynolds

All life is written in his burning pages

However, if Dante speaks to our present condition, it is not because we fear damnation, but because Dante wrote the epic of Everyman who sets out in search of salvation. (A more recent sinner, Jeffrey Archer, subtitled the three volumes of his prison memoirs "Hell", "Purgatory" and "Heaven", presumably after Dante.)

Dante's genius has often been obscured in the English-speaking world, and part of the blame must lie with the Victorians. Clergymen, civil servants and other worthies translated the poet's crystalline cantos into pious fustian, full of righteous morality. There was a message for contemporary society in The Divine Comedy which Christians such as John Ruskin saw it as their duty to convey: the wages of sin shall be known in purgatory. Recast as Victorian hymnology, The Divine Comedy became the most earnest of poems. Even Longfellow's translation of 1865-1867, much admired, is now known for its timid expurgations and literalisms.

Yet, awkwardly for the Victorians, parts of the epic are pretty ribald. (How translators must have agonized over Canto XXI of The Inferno, where the devilish Malacoda makes a "bugle" of his arse by breaking wind musically.) When William Burroughs' Naked Lunch was prosecuted for obscenity in Boston in 1965 (the "talking asshole" chapter), Dante was cited in the novel's defence.

After the Victorian distortions, who put the fizz back into Dante? None other than Dorothy L Sayers, the detective novelist. Many who know Dante from the Penguin Classic (published between 1949 and 1962) are surprised that most of it was translated by the same Sayers who gave us the dandified sleuth Lord Peter Wimsey. For the last 13 years of her life, Sayers worked devotedly on Dante. Her translation was energetic if at times stilted; its colloquialisms at least were in keeping with Dante's Italian.

Barbara Reynolds, author of this excellent critical biography of Dante, completed Sayers' translation of The Divine Comedy after the author's death in 1957. Reynolds is a world authority on Dante, and this book is the summation of a lifetime spent lecturing on the poet. Unfailingly lucid, it provides a scholarly reading of the works, and does not flinch from confronting unsavoury aspects of Dante's personality.

In The Divine Comedy, Dante exacts a pitiless revenge on former associates, politicians and other humbugs who had ruined (so he thought) his native Florence: some are boiled alive in brimstone, others trapped in ice. Now, 700 years on, Dante has no equal as a singer of other-worldly horror.

He began the first section of his epic three-part poem, The Inferno, in about 1307, five years following his expulsion from Florence for corruption and embezzlement. The charges against Dante were probably false, says Reynolds, but he never set foot in his home town again. Reynolds shows how deeply scarred and humiliated Dante was by banishment. His pride and young ambition dented, he worked with gleeful concentration on his private vision of hell.

With its adrenalin-quickening scenes of horror, much of The Inferno is "awful" in that archaic sense of the word (still valid in Italian), capable of inspiring "awe". The poem, as every Italian schoolchild knows, opens on Good Friday in a supernatural forest at nightfall. Dante, a figure in his own work, has lost his way in middle age and is alone and frightened in the woods. The Latin poet Virgil, sent by the mysterious Beatrice, is about to show him Hell.

Little is known of Beatrice dei Portinari, who died in Florence in 1290. She was the love of Dante's life, yet the poet rarely disclosed her name in his writing (and then only in the abbreviated form of "Bice"). In The Divine Comedy, Beatrice is usually taken to be an allegory of divine grace, but Reynolds suggests other roles for her, some of them not defined before. She appears before the speechless Dante as a veiled woman in robes the colour of "living flame", and was later worshipped by the Pre-Raphaelites as a dewy eyed damsel, tender as a marshmallow. (Rossetti's Beata Beatrix, now in Tate Britain, illustrates the lachrymose ideal.)

Throughout this spendid book, Reynolds commends Dante as a radical for choosing to write in vernacular Italian instead of Latin. Dante's overthrow of Latin preceded Chaucer's by 80 years; by writing in Italian, he was able to reach a wider audience, and make use of vulgar burlesque, harsh and grating rhymes, as well as invective. The Divine Comedy in fact gathers together an extraordinary range of literary styles, Reynolds says, from "narrative, dramatic, lyrical, oratorical and vituperative". If any writer has a claim to the universal, it is Dante: all life is written in his burning pages.

After a lifetime spent in the various careers of philosopher, soldier, politician and man of letters, Dante died in 1321 of malaria; he was 56. Today he is a national monument, read and re-interpreted by generations of Italians. In If This is a Man, Primo Levi relates how he tried to remember lines from the Inferno at Auschwitz.

The Italian composer Luciano Berio, in his avant-garde homage to Dante, Laborintus 2, used jibberring voices and skewed jazz rhythms to represent the grafters and money-brokers of Hell. For others, T SEliot among them, Dante's brimstone poem was the highest expression of Christian civilisation. The Divine Comedy encouraged Eliot in his conviction that modern man is spiritually shipwrecked. "I had not thought death had undone so many," we read of those lifeless commuters in The Wasteland (words which Eliot cribbed directly from Canto III of The Inferno). In spite of our distance from medieval theology, The Divine Comedy remains one of the essential works of mankind. European literature begins and ends with Dante; he is the patriarch of modern letters.

Ian Thomson's biography of Primo Levi won the Royal Society of Literature W H Heinemann Award 2003