A LENS would reverse things top to bottom...not a mirror. In a full length mirror, you can see your feet also 'seeming' to be reversed left for right, but try to imagine how they could possibly be at the top. It's just that the IDEA of your mirror image being backwards is so strong. If you have two mirrors, you can counter the 'reversal' in the 2nd one, but you still don't get an up-down change.