There's an urban legend that when the Indians first saw Columbus's ships, they weren't able to perceive the ships because they were nothing they'd ever encountered in their world. The validity of the story is often debated, but i think what the story really opens a discussion for is the idea of perception. a guy posting as silas sparkhammer on the snopes boards had some good comments:

Again, go into a forest (if you have never been in one) and you will have a great deal of difficulty finding your way around. This confusion won't last for mere seconds, but for hours and hours. It takes time for the brain to figure out entirely new patterns.

Take someone who doesn't know how to play chess. Take another person who is a master of the game. They both see exactly the same light patterns reflecting off of the pieces on the board...but they perceive *very* different things.

There's also this experiment in visual cognition. Check it out. Did you see it? I saw it.

And that's the thing. Perceiving people on multiple levels. Keeping an eye out for the WTF.

Last night, when I was out people watching, I was thinking about those Indians not recognizing the boats. Maybe there are certain people who are around in your world, but you can't see them because you haven't enough perspective to recognize them. So you recognize they're people, but you don't really "see" them. But when you get into a different place, different eyes, different frames of reference, you can suddenly recognize them. Through your connection with them, they suddenly bring your life to a different level.