For a few brief strokes of a pen, a signature carries a lot of weight in human society. Before pens were a readily available tool, people used stamps for the same purpose. Those stamps are called seals (nowadays you can pick up all sorts of cute wax seals for adding that olde worlde touch to your scrapbook, wedding invitations, or greeting cards). Did you know that some key verses in the Bible tell us that, as believers, need to be sealed, too? But what on earth does that mean, and how (without enlisting the aid of hot wax and an enthusiastic friend) can we be sure that we are actually sealed?