Thomas de Quincey. Engraving of Thomas de Quincey (1785-1859), British writer and opium addict. At the age of 17 he ran away from home but was later reconciled with his family and studied at Oxford University. In 1821 he published Confessions of an English Opium Eater, a graphic description of his experiences as an opium addict. This was his most famous work, although he wrote many others. Opium (which contains morphine) consists of the dried resin from the unripe seed capsules of the opium poppy, Papaver somniferum. Opium is smoked, eaten or injected by users.