Pillow cases hanging on the line

There was a family who had problem with one of their children. A son. This son took off from home one day, and didn't have any contact with his parents for two or three years.

One day, all of a sudden, they received a letter from this boy. He wanted to come home. He wrote, "I would understand if you don't want me to come home, but I would like to. On such and such a day, I will be on the train that goes right past your house. If you will allow me to return home, then on that day hang out a white pillow case on the line. Then I will know to get off the train and come home."

Well on that day, the son was on the train. And as he approached that house he was looking -- straining to see if he would be able to catch a glimpse of a white pillow case on that line. As he was looking, as the train rounded the corner that allowed him a view of his parents house, what did he see? There was not a white pillow case on the clothes line. But there was white everywhere over the back yard -- anything white, pillow cases, bed sheets, T-shirts -- hanging from the windows, the trees and the clothes line.

Source: James Beeke, Fall, 2008