The morality of the poor
De Quincey says the true philosopher should be willing to associate with all kinds of people, including prostitutes and the poor (20). He frequently digresses from the narrative to suggest ways to make life better for the English poor (21), a concern that was probably influenced by his brief period of poverty as a runaway adolescent in London. Throughout the memoir, he admires the conduct of the poor and frames them as being morally superior to the rich. For example, De Quincey admires the generous conduct of the butler on the roof of the mail-cart, and in "The Pleasures of Opium," he argues that the poor exemplify virtues that the rich do not. Perhaps the most meaningful manifestation of this theme is Ann, to whom he remains indebted even at his time of writing. Especially considering how De Quincey frequently suggests the misery of life, these acts of kindness have special weight in his narrative.
The life of the mind
De Quincey differentiates between himself and the people around him by describing himself as a "philosopher." He believes that having a rich life of the mind justifies behavior that would otherwise be considered questionable, like running away from boarding school. In many ways, his many implicit defenses of his work as one of literary value suggest that a literary, philosophical sensibility defends even the overuse of drugs. Later in the memoir, he suggests that one of the worst effects of opium was its destruction of his ability to focus on his studies.
Nostalgia
Nostalgia frequently crops up in Confessions of an English Opium-Eater; it is at once a motif and a source of aesthetic beauty. De Quincey romanticizes events that were unpleasant at the time, and his gritty depiction of his life in London is tempered by his longing for Ann in later years. At the beginning of Part II, De Quincey stops the narrative to reflect on the fact that he is no longer a student, a reality he conveys using the language of death and decay (50). The memoir's nostalgia is invariably tinged with melancholy; for example, when he wanders past the old house in London, De Quincey sees a happy family and feels excluded and alone. The reflective nature of his memoir is itself a manifestation of the theme, as well as an attempt to give the work a personal and emotional weight greater than its exploitative 'drug-user' content might require.
The commodification of pleasure
In the section devoted to "The Pleasures of Opium," De Quincey dwells extensively on the cost of the drug. Although the cost was not a major issue for him (at least at this time of his life), he is preoccupied with the concept that the drug's transcendental pleasure can be bought and sold for money. This ties into his concern for social inequality; he suggests that, since this drug has the power to raise us above the misery of everyday life, the rich are able to escape the sufferings that the poor must endure because they cannot afford opium.
Wandering
Throughout the memoir, De Quincey reflects fondly on the many nights he has spent wandering the streets of London. Although this is one of his favorite pasttimes, wandering is presented ambiguously: it often fills him with sadness when he visits the poor districts and witnesses the hardships people have to endure, and he offers the Malay opium as a “respite from the pains of wandering” (57). De Quincey also presents life as a long, depressing period of wandering, without structure or a governing logic. The fact that he is nevertheless drawn to continue wandering suggests one of his personal contradictions that he explores in the memoir.
The writing process
De Quincey directly discusses many of the problems and decisions one faces when writing one’s own autobiography. He frequently introduces new topics with an explanation of why the topic is necessary or relevant, and anticipates potential objections that readers might make. Part of this is due to De Quincey's literary tradition – although he borrows from the conventions of fiction and memoir, he is also deeply engaged with the tradition of the classical essay, which often used direct address and privileged clarity of argument over grace of expression. This theme is perhaps most solidly discussed in terms of his ambition - though he no doubt knew he was writing a piece that would be popular for its exploitative content, he nevertheless maintains an ambition to craft a work of literary and intellectual value. This contradiction provides him many occasions to explicitly or implicitly defend the work's value, and can potentially help explain some of its more profuse devices, like apostrophe and dense allusions.
Dreams and the subconscious
Descriptions of De Quincey's opium nightmares take up a large part of the section devoted to "The Pains of Opium." They merit such extensive attention because De Quincey believes that dreams are representations of the subconscious, and that by relating these images, he reveals the depths of his personality and suffering. His belief is so important that he uses it to partially defend the amount of detail he provides on his impoverished youthful period, since those experiences will later grow perverted in the grips of opium dreams. Many of the memoir's other themes are expressed through dreams, including nostalgia (De Quincey dreams of Ann and other people from his past) and wandering (he goes on long, aimless dream walks just as he does in waking life). Dreams also provide a vehicle for seemingly unimportant memories to reappear; the final three dreams in the memoir can be read as De Quincey underlining the most important moments of his life for the reader. Such a psychological understanding of how our waking life and dream life inform one another was certainly sophisticated for its time, and remains one source of the memoir's enduring legacy.
