Here's our deep thought from Sunday brunch: one learns in 5th grade that the image of the outside world that ones brain receives from the optic nerve is inverted. The light that comes from the plane above eye level passes through the lens and is reflected onto the bottom of the optic nerve, and the light that comes from the below that plane is reflected onto the top. The reason we know it's not the optic nerve or its connectors that switch bottom to top is illustrated by the film I saw in the same 5th grade science cycle. They took a guy and put this apparatus over his eyes that switched the image he saw with a couple of mirrors--what was being fed to his eyes was already upside down. He wore the device continuously, and a week or two later, his brain adjusted and he started seeing right side up again. They showed him riding a motorcycle to prove that he could see okay. Question: Did his brain just undo the flip that it normally does, or did it flip the image again? Is there any physiological difference between these two things? Sub-question: Why hasn't someone released all of those fifth grade science films from the 1950's on DVD? First, they rocked. Second, it would prove that I wasn't crazy, since nobody seems to have seen this particular film except me.
Anyway, this all struck my ten-year-old brain as impossible. On the one hand, the dude could ride a motorcycle, and that's pretty compelling evidence. On the other hand, it seemed to ten-year-old me that you see from your eyes, not your brain. I didn't even buy that the image from my eyes was somehow upside down in the first place. I mean, I was looking right at it. I could see that it wasn't upside down.
So here's the deep thought. If your brain does something as dramatic as invert the image your eyes receive before you actually "see" it, what the hell else is it doing? What's being received that you don't see? What's not being received that you do?
(Editor's Note: this post markedly more interesting if you are stoned.)