The story’s opening paragraph introduces the idea of mental illness. The narrator’s repetition of words like “nervous,” “mad,” and “heard” foreshadows the main themes: madness caused by sharpened senses and denial of madness by the person suffering from it. Thus, the short story can also be read as an investigation of the concept of “insanity defense,” which gained notoriety in 1843 in the wake of Daniel M’Naghten’s murder trial.

The narrator’s obsession with a particular body part, an eye, illustrates the process of mental deterioration. It also marks the beginning of a process of dehumanization. By divorcing the old man as a person from his eye, the murderer can compartmentalize their emotions. They state that “I loved the old man” and that it was “not the old man who vexed me, but his Evil Eye,” demonstrating how the eye becomes a separate, personified entity in the narrator’s mind (Paragraphs 2, 3). The body dismemberment after the murder further renders the old man into pieces of flesh, creating a sense of dissociation from the crime.

However, despite the narrator’s attempt to physically hide the evidence and mentally disengage from their terrible act of murder, they are unsuccessful in escaping punishment.