I can turn my head but that hides exactly as much as it reveals. Fully one half of the world is hidden from me at every moment! This is alarming!
What hides half the world? Me, myself. Literally, half the world is hidden from me by the fact of my own presence in it. I am my own blind spot. No matter where I look, there is a big hole in the universe that reminds me of my own existence.
I am the invisible one. I see, but I do not see the one who sees.
Why is it that way? If our eyes were on flexible stalks rising above our head, we could see all around, both forward and backward at the same time. For an animal so extremely dependent on vision as we are, that would have been a better design. We got cheated.