De Quincey was a well-known 19th century English journalist and essayist. He was orphaned at a young age and sent away to school, where he was successful but bored and soon ran away. He then spent several years living as a vagrant in Wales, then London. In London, he was reunited with an old family friend who supported him financially and sent him to study at Oxford.
At age 28, De Quincey began to use opium (mixed with alcohol in the form of laudanum) regularly to treat his severe stomach pains. Though his intake was moderate at first, he soon became addicted. At first he rationalized the use of the drug. Later, he experienced opium-induced stupors in which he could not distinguish dream from reality nor note the passage of time.
He also developed memory loss and long periods of depression. He resolved to wean himself from the drug and did so, although in the final version (1856) of this memoir he admits to having slipped back into addiction a number of times.