Edgar Allan Poe is renowned for his mastery in creating horrific and terrifying images through his choice of language and diction. The impactive nature of his word choice tends to insure that readers are taken to the brink of madness along with the (typically) unreliable narrator. In regards to "The Fall of the House of Usher," the opening of the text proves to be typical of Poe's image ridden language. Words such as dark, oppressive, dreary, soundless, and alone focus upon one singular purpose: establishment of the mood.
An essay with the purpose of defining how Poe's diction and imagery establishes the mood could begin in a couple different ways. First, one could use a narrative pattern of development. This pattern of development would allow the essayist to illustrate the power of language. A narrative introduction would tell a story which illustrates the power of ominous words over the mood of a text and, therefore, the reader.
Second, one could use a cause and effect pattern of development. With this, the essayist would illustrate the power of dark and heavy words over those which do not contain the same heavy nature. For example, one could illustrate how words such as cold, solitary, and oppressive contrast the mood which is brought about by words such as warm, sociable, and gentle.
The body paragraphs of the essay would then support, through textual examples, the impactive nature Poe's language has on the mood of "The Fall of the House of Usher."