In Edgar Allan Poe's "A Tell-Tale Heart", what is the disease the narrator is speaking of?
I am currently working on a literary criticism on the piece, and am trying to break the story down piece by piece. Poe writes, "TRUE! - nervous - very dreadfully nervous I had been and am; but why will you say that I am mad? The disease has sharpened my senses - not destroyed - not dulled them." What is the disease?!? Is it madness? Is Poe trying to trying to prove the narrator's insanity by showing his lack of reasoning?
If anyone has read (and understood), done a report or paper, or just knows a little about this story and could please give me some help, I would really appreciate it.