Your salary may come in the mail, but originally it comes from the Latin adjective salarius, meaning pertaining to salt.  Roman soldiers used to receive a handful of salt everyday.  Eventually the salt was replaced with money, and the soldiers could go buy as much salt as they wanted.  Money is a good thing, especially with my high blood pressure.  If I just got handfuls of salt all the time, I probably would just quit working.  Especially considering the fact that I have big hands.  I would be getting way too much salt.