After reading all the contributions to this thread, I just have to put in my 2C worth. I think you have to do what is comfortable for you. If you feel guilty about keeping something that doesn't belong to you, give it back. If you don't feel guilty about it, there's no need to justify it (because you can't), just keep it. There's no need to sugarcoat anything. We'll all mature enough to know there is a difference between what you should do and what you actually do. I don't think there is a "sliding scale" about how large or serious the mistake is, it is something that doesn't belong to you. If you decide to keep something that doesn't belong to you, just do it and get on with life. Don't make excuses or look for someone or something to justify what you did. I don't think there is a person alive who is 100% honest or 100% dishonest. Remember the saying: "You know what you did."