At first, his paranoia gives him the irrational fear of the vulture's eye which brings him the urge to kill the old man.
Being the first story I have read which is a psychological thriller and horror story at the same time, I become very much interested and involved with the story. I can say that this is one of the best stories of murder I have ever read as it explores how people with psychological disorders think and why they do the things that they do. In the end, the Tell Tale Heart also acknowledges the conscience within man by showing how the relentless heartbeat of the old man bothers the murderer. It simply portrays that even though the murderer become greatly satisfied because he was able to rid himself of the object of his fear, he still has this innate longing to do what is right as dictated by his conscience. With the Tell Tale Heart, Edgar Allan Poe is highly successful in affecting and influencing readers like me.
On the other hand, The Cask of Amontillado is a more intricate and complicated plot of murder. I can say that Edgar Allan Poe is able to devise and show the perfect plot for murder. As opposed to The Tell Tale Heart which tackles paranoia and guilt, the main theme of the story is revenge.