This biography of the craven Romantic and self-confessed ‘Pope of Opium’ concludes with the ominous words: ‘We are all De Quinceyan now.’ His life was shambolic but his legacy is strong. Many spores from his fevered mind have lodged in modern popular culture: his narcotic excursions inspired Baudelaire and Burroughs, his sensitivity to place influenced the psychogeographers Guy Debord and Iain Sinclair, his laconic, jaunty essay ‘On Murder Considered as One of the Fine Arts’ was deemed ‘delightful’ by Alfred Hitchcock, and his Escher-like imaginative double consciousness prompted Jorge Luis Borges to ask: ‘I wonder if I would have existed without De Quincey?’

And yet behold the man himself. Broke, pompous and high as a kite, he dressed like a beggar and wrote surrounded by an ‘ocean’ of books, papers and candles so that, as Frances Wilson dryly notes, ‘It was habitual for his daughters to point out to De Quincey as he worked that his hair was alight’. By turns amused, appalled and empathetic, Wilson paints such a riveting multi-tonal portrait that one ends up with a strong regard for De Quincey’s rare vision but at the same time an absolute certainty one would not invite him to dinner.

Torpid until midnight, his conversation would take off just as the other guests were leaving, reaching a peak of ‘diseased acuteness’, according to Thomas Carlyle; he might then stay on as a guest for weeks on the smallest pretext, borrowing money, leaving behind the stacks of papers that always attended him, and probably ending up by revealing damning details about his stay a few years later. He was a great writer, but became, like so many junkies, a lousy friend.

He created his own mythos through autobiographical sketches — such as the Gothic description of the moment, when he was six and his beloved sister Elizabeth had died aged nine, when he stole into her room to kiss her marble lips while a hot summer wind blew like an ‘audible symbol of eternity’ and he ‘slunk, like a guilty thing, with stealthy steps from the room’; Wilson adds that he (probably) listened outside the door afterwards while two doctors sawed open her head during the autopsy. Wilson shows how this characteristic interplay of violence, transcendentalism and psychological acuity recurs throughout his writing; she beautifully binds and catches us in the web of his imagination, and this is the point: ‘There have been several fine biographies of De Quincey, but so far no De Quinceyan biography.’

As a lonely teenager he was profoundly affected by the works of Wordsworth and Coleridge, and he cultivated their friendship, lying in wait to foist presents on them. Aged 17, he ‘ambushed’ Coleridge for the first time and gave him a rare Latin pamphlet by the philosopher David Hartley, after whom Coleridge’s eldest son was named. Toadyish — but it worked, and De Quincey slowly ‘elbowed’ his way in.

At Oxford he was too conceited to attend any tutorials (‘Oxford, ancient Mother! Hoary with ancestral honours… I owe thee nothing!’ he later wrote) and as soon as he could, he joined his idols in Grasmere, where by the age of 24 he had become a friend to Dorothy Wordsworth and tutor and playmate to the Great Men’s children, burning through his inheritance in an attempt to win everyone over. Sensitive to moral ambiguities, Wilson notes how freely his elders accepted his books, loans, sponsorship and time, little wondering what the cost would be. ‘Coleridge had his suspicions, but Wordsworth had no idea that this mild creature, so keen to please, would be capable of writing about them with such candour.’

When De Quincey’s Lakeside Reminiscences were published 30 years later, Southey damned him as a ‘base betrayer of the hospitable social hearth’. It is full of details such as Dorothy Wordsworth having ‘no personal charms’ and William using a buttery knife to split the pages of De Quincey’s Burke. Wilson nimbly compares it with another classic of friendship recollected from a distance, A.N. Wilson’s Iris As I Knew Her, but gratefully defends De Quincey’s journalism as a rare and vivid source of biographical information about the Romantics.

‘Opium was the making of De Quincey,’ writes Wilson, frank about the fact that this study prizes him as a writer rather than a person. It made him a hopeless provider for his seven children (one son died fighting the Opium War with China) but gave him a form of synaesthesia, allowing him to see in the ‘elaborate harmony displayed before me, as in a piece of arras-work, the whole of my past life’. His descriptions of an opium night passing as slowly as 70 or 100 years still thrills, but context makes it almost more incredible. Wilson writes:

We see him as one of us, a voice anticipating our own age of recreational drug use, but this was not how he was read in 1821, when the whole country was marinated in opium, which was taken for anything from upset stomachs to sore heads.

According to Mike Jay, the author of Emperors of Dreams, a study of drug-taking in the 19th century, De Quincey

recast a household habit as a personal and unique transgression; not so much breaking a taboo as deliberately creating one by recasting a familiar practice as transgressive and culturally threatening.

Complicated; but ‘nothing De Quincey wrote was ever straightforward’. ‘A fearless ironist, his mischief worked in curious ways,’ uniting ‘playfulness, venom, ambition, revenge and self-perception’. He was a transcendental hack; a faithful husband but selfish loner; a writer of the highest ambition with an obsessive interest in writing about murder; an acolyte uplifted by the Romantics, but always kept in their shadow; a visionary whose writing is all ‘I’ but no ego:

The self he describes in Confessions and other autobiographical essays is a fleeting form on the cusp of disappearing — into a city crowd, into the chasm of a dream or into some other body entirely.

In her pursuit, Wilson often catches decisively this most elusive character, and the chase is exhilarating.