This is one of the nicest explanations for one of the deepest mysteries of our modern (as in post Bronze Age) technological era: Why is it that when you look in a mirror, left and right are reversed, but not up and down?
The answer is simple: Neither is reversed. What is switched around is not one side vs. the other or top vs. bottom, but rather, which side of your face your nose is on. When you look in a mirror, you do not see the back of your head. The image in the mirror is the image of yourself with front and back reversed. All else follows from that.
Anyway, enjoy the show. Hat tip: clevedan….
Richard Feynman and the Looking glass: