The Narrator's Insanity In 'The Tell-Tale Heart'

This demonstrates how he gains confidence on the action he has done. Also, the narrator believes that he can take away the live of the old man without any consequences. Significantly, this shows how the narrator is emotionally unstable because he has a satisfaction when he kills the old man.
To conclude, the narrator from “The Tell Tale Heart” is insane because he is emotionally unstable. After killing the old man and feeling fulfillment, the narrator cannot control his emotions towards hearing the old man heart and he confesses himself. Guilt and fear affects the narrator's mental defences. Consequently, the narrator admits his crime and has a mental destruction. All in all, this shows how the mind of the narrator is acting against itself