When I was in college, they used to show movies in a lecture hall that was tiered at a deep angle down to the front of the room. As soon as you entered the door from the rear, you had to go down an aisle of very steep stairs. I remember arriving late once, after the movie had already begun. As I tried to find a place to sit, it was so dark in the room that I nearly wiped out trying to negotiate the stairs. I ended up practically crawling on my hands and knees, groping my way to a seat. At the time I realized that people around me were laughing but it didn't occur to me that they were laughing at me. That is, until I was seated and watched as the next group of people entered the darkened room. By then my eyes had adjusted to the darkness, and I could see them carefully feeling their way aro…