Most humans are born with two eyes with which they see the world.
Two perfect mechanical structures working in sync with each other to bring you the the sights and images of this world we live in.
I like to think that the world is a balance of positive and negative. With two eyes you can see both.
Close one eye and you can see light reflecting on the surface of a metallic sphere. Open it up and close the other. Now you see the shadows more clearly.