If you take something that doesn't belong to you, you have to return it; right? Well... not always. The Torah reveals to us some interesting details in what are the appropriate actions to be taken in case one has erred and taken something that doesn't belong to him. As an important aside, I'd like to take this opportunity to explain a detail in how I phrased that introduction. It is a mistake to say that the reason stealing is wrong, or eating pork is wrong, or tying a permanent knot on Shabbos is wrong is because the Torah says so. Rather, we do them because HaShem -- our Creator, who therefore has the right to tell us what to do and how to do it -- told us not to do those things. How do we know Ratzon HaShem? HaShem has revealed that to us via His Torah. How do we know that the Torah (Oral and Written) that we have today is an accurate revelation of His Will? That's another question for another time. The point is that the Torah is the...
This is a paraphrase of the pasuk in t'hillim 84:7 -- "mei'chayil el chayil" -- which means "from strength to strength". In this case, it is my thoughts and ideas to those who are strong enough to be interested :)