What evidence can you find that the narrator's state of mind may be deteriorating?
In "The Fall of the House of Usher," Poe builds a mood of gloom and foreboding in his Gothic tale. The narrator declares,
During the whole of a dull, ark, and soundless day ...when the clouds hung oppressively low in the heavens, I had been passing alone,...through a singularly dreary tract of country; and...found myself, as the shades of the evening drew on, within view of the melancholy House of Usher....but, with the first glimpse...a sense of insufferable gloom pervaded my spirit.
After reflecting upon the history of his friend, the narrator looks up at the House of Usher and feels a "superstition" which continues after he enters the mansion. where he feels that he breathes
an atmosphere of sorrow. An air of stern, deep, and irredeemable gloom hung over and pervaded all.
Through this story, the narrator absorbs "the depression of soul" that the decaying trees and crumbling building generate. When he encounters his old school friend, Roderick Usher, the narrator is astonished by the appearance of the man. His "sickening of the heart" continues to pervade him as he becomes increasingly concerned with the friend's mental state, reflected in the "ghastly pallor" of the man. And, although the narrator makes great efforts to alleviate the melancholy of Roderick, only one unceasing radiation of gloom" prevails.
However, as the narrator attends Roderick in his painting, he experiences "intolerable awe" at his work. But, a "nervousness" comes upon the narrator, "irrepressible tremors" pervade his heart, and he experiences "an intense sentiment of horror, unaccountable yet unendurable." In his efforts to calm Roderick, the narrator reads to him from the "Mad Trist," but he hears a scream and a grating sound which unnerves and oppresses him. As Madeline stands "lofty and enshrouded" at the door, she falls and makes him the victim of the very terrors he has anticipated. The narrator, too, is terrorized.
In the "mansion of gloom,"
Although there is evidence within the first few sentences of the story that the narrator may not be completely rational, the best evidence that the narrator's state of mind may be deteriorating is that he says so himself. In speaking about Usher's horrid condition, the narrator says, "It was no wonder that his condition terrified--that it infected me. I felt creeping upon me, by slow yet uncertain degrees, the wild influences of his own fantastic yet impressive superstitions."
There are additional examples as well. First, the narrator speaks within the first paragraph of the text as if he is seeing things that are not really there. He speaks of the "vacant eyelike windows" and "sense of insufferable gloom" that added to his "utter depression of soul." Further, the narrator’s irrationality takes a turn for the worse after Madeline's corpse has been stowed. "Sleep came not near my couch . . . and, at length, there sat upon my very heart an incubus of utterly causeless alarm" and he paced "rapidly to and fro through the apartment." Even the end of the story can be questioned. Here our narrator supposedly observes the House of Usher literally falling to the ground in ruin. As readers we are left wondering if Usher's home really fell or whether we have once again fallen victim to our affected narrator.
For once, he enters the house (that's an allegory to a brush or future brush with your inner fears and insanity). Then, after he experiences the shock of the first look of his friend and the house, he starts becoming uneasy. Seems as if Roderick is slowly starting to enthrall him into his own state of mind, as the narrator then starts losing sleep at night. When the sister dies, you see how he goes along with the idea of burying her in the household cemetery. After the vision of the sister happens in the end (which we do not know if was an actual vision or the sister crawling out of her grave) the narrator saw the same thing and as he ran the house fell right behind him. Seems as if the whole thing is an explanation of a journey into insanity.