An incident at a grocery store the other day got me thinking about a philosophical question I had never before considered. I had gotten in a line that had recently closed and had begun to unload my groceries onto the checkout counter. Before I put very many of them down, the clerk alerted me to the fact that this line was closed and pointed to a sign stating as much. I subsequently put the groceries back into my cart and moved to another line.

While I was waiting in the new line, I started to wonder how I could know for sure that THIS line wasn't also closed. I didn't see a sign stating that it was closed but, then again, I didn't see that other sign, even though it was obviously there. So could I really be sure, based on sight alone, that there was no sign stating that this line was closed?

But this all begs some even more serious and frightening questions. When driving down the road, how can you ever know for sure there aren't any people or animals in your path that you are about to hit? How does the bomb squad, even after checking a building in response to a bomb threat, know for sure there is no bomb planted in it? How could you ever know for sure that there aren't any intruders lurking in your house? This list could go on and on, of course.

Have you ever failed to see an object that was right under your nose? We all have at one time or another. That just goes to show us that we cannot always trust our sight. They say "seeing is believing" and this is very true, but not seeing should never be a basis for not believing or having any assurance of the absence of anything.