English essayist and critic, best-known for his autobiography Confessions of an English Opium-Eater, which appeared first in 1821 in London Magazine. De Quincey was addicted to opium from his youth for the rest of his life. His influence on such writers as Poe and Baudelaire, and a number of readers tempted to experiment with opium, has been immense and notorious.

"If opium-eating be a sensual pleasure, and if I am bound to confess that I have indulged in it to an excess, not yet recorded of any other man, it is no less true, that I have struggled against this fascinating enthralment with a religious zeal, and have, at length, accomplished what I never yet heard attributed to any other man - have untwisted, almost to its final links the accursed chain which fettered me." (from Confessions of an English Opium Eater)

Thomas Penson Quincey was born in the industrial city of Manchester, Lancashire. His father, Thomas Quincey, was a wealthy linen merchant; he died in 1793. A few years later the family moved to Bath, where his mother Elizabeth Penson took the name 'De Quincey,' which sounded more aristocratic.

De Quincey was educated at schools in Bath and Winkfield. In Confessions De Quincey tells that when he was thirteen he wrote Greek with ease, and at fifteen he composed Greek verses in lyric metres and conversed in Greek fluently. "That boy," his master at Bath had said, "that boy could harangue an Athenian mob better than you or I could address an English one."

At the age of 17 De Quincey ran away from Manchester Grammar School to Wales – with the knowledge and support of his mother and uncle. Before returning back home, he lived on the streets of London in poverty and hunger. Later in life he often saw in his dreams "Anne of Oxford Street," a 15-year-old prostitute who showed kindness to a young runaway.

Throughout his life, De Quincey suffered from stomach pains. To opium, in the form of laudanum, De Quincey became addicted in 1804, when he studied at Worcester College, Oxford. He used it first to relieve acute toothache. He kept a decanter of laudanum by his elbow and steadily increased the dose. The drug was widely used to treat everything from syphilis to the common cold.

De Quincey left Oxford without taking a degree. In 1807 he became a close friends with the romantic writer Taylor Coleridge, whom he met on a visit to the fashionable town of Bath. Coleridge introduced his new friend to Robert Southey and William Wordsworth, whom De Quincey greatly admired. In 1809 De Quincey went to live with them in the Lake District village of Grasmere. Suffering a series of debilitating illnesses between 1812 and 1813, De Quincey began to take opium again. A daily user, it was not until about 1817 he was able to control his habit.

In 1816, De Quincey married Margaret Simpson, a farmer's daughter, with whom he already had a child. She was the fixed point in his life; they eventually had five sons and three daughters.

Having spent his private fortune, De Quincey started to earn living by journalism. He was appointed as an editor of a local Tory newspaper, the Westmoreland Gazette. For the next 30 years he supported his family, mainly in Edinburgh, by writing tales, articles, and reviews. Early in the 1820s De Quincey moved to London, where he contributed the London Magazine and Blackwoods. His chronicle Confessions of an English Opium Eater, which first was published in London magazine and then reprinted in book form, was a mixture of stories about his life, social comments, cultural anecdotes, and descriptions both the ecstasies and the torments of the drug. Subtitled "Being an Extract from the Life of a Scholar" De Quincey drew a sharp distinction between himself and other junkies; moreover, though he preferred laudanum, opium dissolved in alcohol, he defined himself as an opium-eater, not drinker or smoker. The book was an instant success and an important inspiration for other writers. Confessions – its title noteworthy referring to the Confessions of St. Augustine – also included quotes in Greek, Latin and Italian. Without considering its intellectually and physically corruptive effects, De Quincey took the drug in hope of increasing his rationality and the sense of harmony. For him opium was not a part of criminal, alienated lifestyle.

In 1826 De Quincey moved to Edinburgh. After the death of his wife in 1837, he began to use opium heavily. Between the years 1841 and 1843 he hide the creditors in Glasgow, and published then The Logic of the Political Economy (1844), a dissertation on David Ricardo's economic theory, and Suspiria De Profundis (1845), the sequel to his Confessions, in which he documented his childhood, dreams, and fantasies. From 1853 until his death De Quincey worked with his Selections Grave and Gay from Writings Published and Unpublished by Thomas De Quincey.

Althhough De Quincey wrote much, he published only few books and had constant financial difficulties. Most of his works were written for periodicals. He also examined such German philosophers as Immanuel Kant, Gotthold Ephraim Lessing, Jean Paul Richer, and Friedrich von Schiller, and translated their writings. De Quincey's strong points were his imagination and his understanding of altered states of consciousness, of which he had his own doubts: "The mere understanding, however useful and indispensable, is the meanest faculty in the human mind, the most to be distrusted; and yet the great majority of people trust to nothing else, – which may do for ordinary life, but not for philosophical purposes." (The Knocking at the Gate in Macbeth, 1823)

De Quincey's influence has been later seen in the works of Edgar Allan Poe, Charles Baudelaire, Aldous Huxley, and William Burroughs. Like Poe, he was interested in the criminal mind, though he was not always deadly serious with the subject: "If once a man indulges himself in murder, very soon he comes to think little of robbing; and from robbing he comes next to drinking and Sabbath-breaking, and from that to incivility and procrastination." (from Murder Considered as One of the Fine Arts, 1827) It has been suggested that De Quincey prefigurated modern Outsider-writers such as Alexander Trocchi, for whom drugs served as confirmation of their alienation from mainstream society.

For further reading: Thomas De Quincey: His Life And Writings by Alexander Hay Japp (1877); A Flame in Sunlight by E. Sackwille West (1936); Thomas de Quincey by H.A. Eaton (1936); Thomas De Quincey, Literary Critic by J.E. Jordan (1952); The Mine and the Mint by A. Goldman (1965); The Infection of Thomas De Quincey: The Psychopathology of Imperialism by John Barrell (1991); De Quincey's Art of Autobiography by E. Baxter (1991); De Quincey's Disciplines by Josephine McDonagh (1994); A Genealogy of the Modern Self: Thomas De Quincey and the Intoxication of Writing by Alina Clej (1995); De Quincey Reviewed: Thomas De Quincey's Critical Reception, 1821-1994 by Julian North (1997); The Romantic Art of Confession: De Quincey, Musset, Sand, Lamb, Hogg, Fremy, Soulie, Janin by Susan M. Levin (1998); Romanticism and Masculinity: Gender, Politics and Poetics in the Writings of Burke, Coleridge, Cobbett, Wordsworth, De Quincey, and Hazlitt by Tim Fulford (1999); Thomas De Quincey: Knowledge and Power by Frederick Burwick (2001); De Quincey's Gothic Masquerade by Patrick Bridgwater (2004); Thomas De Quincey: New Theoretical and Critical Directions, edited by Robert Morrison and Daniel S Roberts (2008); The English Opium-Eater: A Biography of Thomas De Quincey by Robert Morrison (2009)  

Selected bibliography:

• Confessions of an English Opium-Eater, 1821 (revised edition, 1856)
  - Englantilaisen oopiuminkäyttäjän tunnustukset (suom. Ville-Juhani Sutinen, 2007)
• On The Knocking At The Gate, In Macbeth, 1823
• Walladmor: “Freely translated into German from the English of Sir Walter Scott” and now freely translated from the German of G W H Haering into English, 1825
• On Murder Considered as One of the Fine Arts, 1827 (in Blackwood's Magazine, extended in 1839, a "Postscript" in 1854)
  - Murha taiteenlajina (suom. Ville-Juhani Sutinen, 2009)
• Klosterheim; or, The Masque, 1832 (edited by John Weeks, 1982)
• Letters of De Quincey, the English Opium-Eater, to a Young Man Whose Education Has Been Neglected, 1843
• The Logic of the Political Economy, 1844
• Suspiria De Profundis, 1845 (published incompletely)
• Joan of Arc, 1847 (in Tait's Edinburgh Magazine)
• The English Mail Coach, 1849 (in Blackwood's Edinburgh Magazine)
• Biographical Essays, 1851
• The Cæsars, 1851
• De Quincey's Writings: Thomas De Quincey, Vol 5, Life and Manners: from The Autobiography of an English Opium-Eater, 1851  
• De Quincey’s Works..., 1853-63 (15 vols.)
• Selections Grave and Gay, from the Writings, Published and Unpublished, by Thomas De Quincey, 1853-1860 (14 vols., ed. and rev. Thomas De Quincey)
• Biographical Essays, 1854
• Literary Reminiscences, 1854 (2 vols.)
• Autobiographical Sketches: With Recollections of the Lakes, 1854
• Letters to a Young Man, and Other Papers, 1854
• Miscellanies: Chiefly Narrative, 1854 (2 vols.)
• Theological Essays and Other Papers, 1854 (2 vols.
• Essays on Philosophical Writers and Other Men of Letters, 1854-60 (2 vols.)
• Sketches: Citical and Biographic, 1857
• Studies on Secret Records, Personal and Historic, 1857
• China: A Revised Imprint of Articles from "Titan," 1857
• Essays Sceptical and Anti-Sceptical on Problems Neglected or Mis-conceived, 1858
• Leaders in Literature with a Notice of Traditional Errors Affecting Them, 1858
• The Avenger, a Narrative; and Other Papers, 1859
• Classic Records Reviewed or Deciphered, 1859
• Critical Suggestions on Style and Rhetoric, 1859
• Speculations Literary and Philosophic: with German Tales and Other Narrative Papers, 1859 (2 vols.)
• Beauties, Selected from the Writings of Thomas De Quincey, 1862
• Recollections of the Lakes and the Lake Poets, 1862 (1948, ed. by Edward Sackwille-West; 1970, ed. by David Wright)
• Biographies of Shakespeare, Pope, Goethe, and Schiller, and on the Political Parties of Modern England, 1863
• Essays on Philosophical Writers and Other Men of Letters, 1865 (2 vols.)
• Memorials and Other Papers, 1865 (2 vols.)
• Suspiria De Profundis with Confessions of an English Opium-Eater, 1871 (1956, ed. by Malcolm Elwin)
• Essays on Christianity, Paganism, and Superstition, 1877
• The Works of Thomas De Quincey, 1878-81 (12 vols.)
• The Collected Writings of Thomas De Quincey, 1889-90 (14 vols.)
• The Uncollected Writings, 1890 (2 vols., with a preface and annotations by James Hogg)
• The Posthumous Works of Thomas De Quincey, 1891-93 (2 vols.)
• De Quincy Memorials, 1891 (2 vols.)
• Joan of Arc, The English Mail Coach, 1893 (ed. with introduction and notes by J. M. Hart)
• De Quincey’s Revolt of the Tartars, 1896 (ed. with notes and an introduction by Charles Sears Baldwin)
• Revolt of the Tartars; or, Flight of the Kalmuck Khan, 1896 (ed. by Franklin T. Baker)
• Collected Writings, 1896-97 (14 vols., ed. by David Masson)
• De Quincey’s Literary Criticism, 1909 (ed. with an introduction by H. Darbishire)
• A Diary of Thomas De Quincey, 1803, 1928
• Selected Writings of Thomas De Quincey, 1937 (selected and edited, with an introduction, by Philip Van Doren Stern)
• California and the Gold Mania, 1945 (illustrated with sketches from "Punch")
• Recollections of the Lake Poets, 1948 (ed., with an introd., by Edward Sackville-West)
• Niels Klim, Being an Incomplete Translation by Thomas De Quincey from the Danish of Ludvig Holberg, 1953 (edited from the manuscript by S. Musgrove)
• Unpublished Letters of Thomas De Quincey and Elizabeth Barrett Browning , 1954 (edited by S. Musgrove)
• New Essays by De Quincey: His Contributions to the Edinburgh Saturday Post and the Edinburgh Evening Post 1827-1828, 1966 (edited by Stuart M. Tave)
• Selected Essays on Rhetoric, 1967 (edited by Frederick Burwick, foreword by David Potter)
• De Quincey as Critic, 1973 (edited by John E. Jordan)
• Confessions of an English Opium-Eater: and Other Writings, 1985 (ed. by Grevel Lindop)
• The Stranger's Grave, 1998 (edited and introduced by Edmund Baxter)
• The Works of Thomas De Quincey, 2000-2003 (21 vols., edited by Grevel Lindop)
• On Murder, 2006 (edited by Robert Morrison)