I would say anyone who kills a person over his eye is probably a bit insane! In "The Tell Tale Heart" by Edgar Allan Poe, the narrator asks in the first sentence, "...but why will you say that I am mad?" (Poe 1) He goes on to give all the reasons why he should NOT be considered mad, but he is none too successful. The narrator says that "Madmen know nothing," (Poe 1) and therefore he cannot be mad because he carefully planned out the execution (!) of his plan. He proceeds to show us just how crazy he really is.
The narrator of the story tells us that he loved this man, but he could not stand his eye. People do not kill someone they love over their eye. That's crazy. On the night he killed the old man, he said he could hear the man's heart beating louder and louder, and later when the police officers are there, he begins to hear it again, though the man is dead. In the end, his craziness forces him to confess.