In the short story "The Tell-Tale Heart" by Edgar Allen Poe the author shows us more than one symptom of madness - it is important to remember that it is perfectly possible for an isane person to be perfectly lucid, analytical and methodical. He therefore appears normal to outsiders. Later he becomes paranoid and more psychotic.
The narrator is undergoing a psychological breakdown in the story yet he keeps telling us that he is perfectly sane, but he is describing the actions of a mental patient. ‘‘True—nervous—very, very dreadfully nervous I had been and am; but why will you say that I am mad?'' He is able however, to see himself objectively and wonders about his sanity.
I have always thought that the narrator was already quite mad even at the beginning of "The Tell-Tale Heart." He gives a pretty strong clue in the first paragraph when he claims to have "heard all things in the heaven and in the earth. I heard many things in hell." Though he says he loves the old man, he decides to kill him anyway because of the evil, vulture eye. Not a particularly sane reason. Just because the narrator is precise with his planning doesn't mean that he's not already mad. The whole plot to kill someone you love and chop them to bits shows a predetermined obsession that is in no ways rational. The heart that he thinks he hears beating is just another of those things he claims to hear in hell. He is mad from the start and may devolve somewhat by the end, but he certainly doesn't evolve in any manner other than deeper into the depths of madness.
This story is about the narrator's descent into madness. Poe gives us a chilling look inside his tortured mind as the narrator tells us about planning and carrying out the murder of an innocent old man. The narrator admits he loves the old man but must kill him because of the man's "vulture" eye. I would say the man devolves rather than evolves over the story because he completely loses it by the end of the story. He's unable to live with what he has done and ends up confessing to the crime. By the end, the narrator cannot distinguish reality from fiction and will never be able to recover.
In the beginning of the story "The Tell-Tale Heart" the narrator is trying to let us know that he is in control and not crazy. He is being very precise in his description of his reasoning that he had to kill the old man.
The reader begins to feels the tension increasing through the story through the repetition of words and the increased frequency of the use of some words as well as their spacing in the story. The reader's mental disintegration is evidenced by his constant discussion about the man's eye and he effect it has on the narrator.
After the narrator kills the man, he is clam for a brief period but begins hearing the dead man's heartbeat. Either guilt or the schizophrenic brain is hearing that which is not real to the policemen who visit. The reader feels the insane intensity and stress of the man as he tries to ignore the sound of the heartbeat. At the same time the policemen demonstrate to the reader that they do not hear anything.
When the man can no longer handle the situation he reveals everything to the police. He has totally mentally deteriorated.