Internal vs. External Conflict

In The Tale-Tell Heart by Edgar Allen Poe, it describes a man who is terrified of another man's blue eye. He has everything planned out. This guy watches the blue-eyed man every night at a certain time and one night, he decides to kill the man and hides his body under the wood floors, leaving no evidence. He, the murderer, almost gets away with it, but the guilt makes him mentally crazy. The cops come and he lies endlessly, with them not expecting a thing. However, he can' t take it anymore therefore turning himself in to the police. In the end he claims he hears the blue-eyed man's heart beating louder and louder when it was just his mind playing tricks on him. I think the message that Edgar Allen is trying to send out is that; don't do something you'll regret, because us as humans have this thing called guilt, and it's not something that you can control. Guilt will eat you alive. It'll chew you up and spit you out. You can try to shun it out but it will still be there in the back of your head reminding you of the thing you did, and it could eventually drive you insane; just like the killer in the story.