Final answer:
In "The Tell-Tale Heart," the heart symbolizes the narrator's guilt, while the old man's eye represents perceived evil, contributing to the themes of insanity and inescapability of one's actions.
Step-by-step explanation:
In Edgar Allan Poe's "The Tell-Tale Heart", the two controlling symbols of the heart and the eye have significant meanings. The heart is traditionally seen as the seat of emotion, and in this dark tale, it represents the narrator's mounting guilt and conscience as it beats louder and becomes intolerable. On the other hand, the old man's vulture-like, filmy, and pale blue eye may symbolize the narrator's deep-seated fear or some perceived evil quality or malformation, prompting the narrator's obsession towards it, eventually leading to murder.
The eye is instrumental in unravelling the narrator's madness, suggesting that what he perceives through it might in fact be a distorted view of reality, a result of his mental illness. The repeated and heightened focus on the old man's eye causes the narrator to become fixated and lose grip on sanity, while the incessant beating of the heart is a ghostly reminder of his heinous act. Thus, these symbols illustrate the themes of guilt, insanity, the subjective nature of reality, and the inescapability of one's actions in Poe's narrative.