The Evil Eye represents the evilness. -Isn't it weird that the narrator didn't think the old man was evil, just the eye? It's because the eye is a metaphor you idiot.
The Beating Heart represents guilt. -The heart keeps beating after the old man is suffocated.
The Lantern represents that light is generally counter to darkness. -Why does the narrator finally kill the old man once the light is fully shed upon the eye? -The eye could stand for the narrator himself.
Midnight represents the darkest hour. - The narrator is only doing evil things at evil hour.
The Bell represents the end of the narrator. -The part stated that the old man is exposed already.
The Watch represents the journey to death. - Describes how very, very, very slowly he moved.