It is a certainty that there are many things that happen in Edgar Allan Poe's "The Tell-Tale Heart" which no one should ever do; however, there are also a few lessons from the story which we can apply to our own lives.
First, we should never judge people solely by appearance. When the narrator talks about the man he eventually kills, he is clear that there is nothing about the man which he finds objectionable. In fact, quite the opposite is true:
Object there was none. Passion there was none. I loved the old man. He had never wronged me. He had never given me insult. For his gold I had no desire.
The only thing which seems to bother the narrator is the man's eye, something physical which the man could not help or change. Other than this real or imagined physical flaw, the narrator had no problems with this man and, in fact, even loved him. Physical flaws should not determine how we feel about or act toward people.
Second, we do not have the right to be selfish when another person's life is at stake. Maybe the eye was kind of creepy, but the narrator's uneasiness--even unreasonable hatred--with the eye does not give him the right to selfishly get rid of it (and the man). The narrator boldly declares that "I made up my mind to take the life of the old man, and thus rid myself of the eye forever" as if it were his choice and right to do so. It is not.
Third, we should practice self-control of both our thoughts and actions. As soon as the narrator has a thought, he acts on it. Perhaps there are times in our lives when this is an acceptable or even a positive thing to do; however, when the action is something with long-lasting ramifications, like murder, we should be prudent and use sound judgment rather than making hasty decisions.
Finally, we need to understand that our guilt is likely to give us away if we have done something wrong. There is something natural in us, even in this cold-hearted and perhaps insane narrator, which knows right from wrong, and when we have done something wrong our guilt begins to work on us. In this case, the narrator appears to be calm and detached about what he has done, but when faced with the law, he cracks.
The officers were satisfied. My manner had convinced them. I was singularly at ease. They sat, and while I answered cheerily, they chatted of familiar things. But, ere long, I felt myself getting pale and wished them gone. My head ached, and I fancied a ringing in my ears: but still they sat and still chatted. The ringing became more distinct: --It continued and became more distinct: I talked more freely to get rid of the feeling: but it continued and gained definiteness --until, at length, I found that the noise was not within my ears.
Obviously no one has the right to take another man's life without just cause, but there are several other surprisingly useful lessons to be learned from this rather gruesome tale.