In college many years ago I had to wait in a hallway for one of my professors. Across the way a door opened into a history class. The teacher - a tall, bald, white-haired man - entered, put his books down and looked out over the class.

"As you know, my goal in this class will not be to teach you to think for yourselves but to force you to conform to my way of thinking."

As one a hundred pens began scribbling in a hundred notebooks and I could see a look of purest terror creeping over the professor's face.

"No, no!" he shouted. "That was a JOKE!"

For a moment every face turned up to look at him blankly. Then, as one, they all laughed. When I left he was still staring at them, open mouthed.