I once asked a Japanese friend to explain why so many people on the Tokyo subway wore surgical masks. Are they extreme germophobes? Conscientious folks getting over a cold? Oh, yes, he said, yes, of course, but that's only the rubric. The real reason to wear the mask is to spare others the discomfort of seeing your facial expression, to make your face into a disengaged, unreadable blank--to spare others the discomfort of firing up their mirror neurons in order to model your mood based on your outward expression. To make it possible to see without seeing.