It can be said that the old man's blue eye is able to see the evils in the narrator's mind. The eye scares the narrator because he thought that no one could see the impurity of his character, and the fact that the old man treats him kindly is in a way making fun of him. So he comes up with the idea of ​​killing the old man to prevent the healed eye from offending him. Poe precedes Dostoyevsky and modern writers in exploring motiveless evil. The narrator quickly informs us that he killed the old man for none of the usual reasons, but only because he couldn't stand the man's blinded gaze. (enotes) The narrator in this case is an unreliable narrator because he is not of sound mind but pleads for others to think that he is. Killing some because you didn't like the look of their eyes is not a sensible thing to do. The narrator doesn't even step back to realize that the act is murder or what the consequences would be if it were discovered. Throughout the story he is trying to prove, reason exists within him as he lays down the old man's body in a "sane" manner. The narrator struggles with his mental health and asks why if they still thought he was.