Mr. Smith lived in the country but worked in an office in the big city. Five days a week, he commuted by train.
One morning, as he was reading his newspaper on the train, a man sitting behind him—whom Mr. Smith had never met—leaned forward, tapped him on the shoulder, and spoke to him.
The man said, "You're not leading a very interesting life, are you? You get on the same train at the same station at the same time every morning, and you always sit in the same seat and read the same newspaper."
Mr. Smith put his paper down, turned around, and said angrily, "How do you know all that about me?"
"Because I'm always sitting in this seat behind you," the man answered.