The irony in the story is in the second sentence of the first paragraph; the narrator says "The disease had sharpened my senses not destroyed, not dulled them." In my opinion this is ironic, because he believed that his insanity was an asset to his situation, when really it brought about his downfall. Had he not been so self-assured that his scheme would be flawless because of his "heightened senses", he invariably would not have ended up in turmoil. This brings about the next point; it was ironic that after all of his careful planning, he ended up admitting to the police that he had killed the man.
Symbolism is an important aspect of the story. The major symbol is the heartbeat. The narrator believed that the sound was the beating of the old man's heart, but it was actually his own heartbeat, signifying his fear of being caught, and his guilty conscience tormenting him for killing the old man. The vulturous, blue veiled eye clearly represents evil, the evil that the narrator saw in the eye that he was trying to eliminate.
A theme of "The Tell-Tale Heart" is that human nature is a delicate balance of light and dark, or good and evil. Most of the time this precarious proportion is maintained; however, when there is a shift, for whatever reason, the dark or perverse side emerges. How and why this dark side arises differs from person to person. What may push one individual over the edge will only cause another to raise an