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...