If you have ever been the the Harold B. Lee Library on BYU's campus, you know that the stairs across from the circulation desk are pretty worn out. You can see the worn foot tracks of thousands upon thousands of trudging, depressed students climbing up the stairs to find a quiet area to cram material into their swollen brains. The tracks are quite deep and noticeable.
Seeing the stairs today reminded me of a story that my statics professor (not statistics) told me about two years ago when I took that class. He said that many years ago a castle in Europe had the same problem as the BYU Library. The tracks were worn deep into the stone steps. The royal engineer in charge of fixing the problem had the great idea of just flipping the steps over. That would be much cheaper than making new steps and double the life of the stairs in place.
However, when they flipped the steps over they noticed that the other side had worn out spots, too.
Can you guess why?
The people of this old European town had already flipped over the castle stairs! This happened perhaps 100 or 200 years previously. Interesting, isn't it? I think it's neat that both people had the same idea.