I got that Sanity

The Tell-Tale is about a so-called sane narrator having the murderous desire to kill this old man because of his evil eye. Now on to the analysis. I believe the evil eye could refer to how within another person's human eyes, you can see yourself. I have been able to deduce that maybe the eye represented in reflection of the narrators level of sanity. He may have chosen to kill the old man because the blue vulture looking eyes of the old man may have thought that the old man was going to kill him. Taking the initiative, the narrator sought to kill the old man. As I stated early, the eyes of the old man probably portrayed how the narrator was losing their sanity with each passing day.
  The beating heart was most likely a sign of the guilt that the man felt for killing the old man. The beating could have even been the narrator's own heart, seeing as it isn't possible for a heart to still be beating after one's body has been dissesembled. With this in mind, I feel that the narrator earlier explains his heightened senses as a way to deny his own further drop in to insanity. From what we can tell, the narrator and the old man seem to know each other, and are probably neighbors or have a servant & master kind of relationship. In conclusion, the narrator is insane, and needs to be rehab.