In the parsha of "trumas hadeshen" (removing the ashes from the altar), the kohein is told to change his clothes before continuing with the rest of his daily duties (Vayikra 6:4). Rashi comments, "This is not an obligation, rather it is derech eretz ; that he shouldn't wear his normal working clothes and get them dirty while taking out the ashes. The clothing in which one cooks the food for his master is not the same clothing one wears when serving wine to his master." Rashi's comment is difficult for at least two reasons. First, if it is not an obligation, then why does the Torah command it? Second, if the the reasoning is as clear as the example, then why would Torah need to mention something so obvious? The first question we can answer from a Rashi in Eruvin, 104b. The mishna there says that a cohein is allowed to put a bandage on a wound on his hand while working in the mikdash on shabbos. This is another example of "ein shvus b'mikdas...
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 :)