An old man who ran his own company and was about to retire had taken his only son into work one day, who had just qualified with the necessary management diplomas to successfully run the business at a senior level.  On arriving at the building the young man's father said, "Follow me, son.  There's something that I need to teach you if you're serious about takiing on this business once I retire."

And with that the old man walked into the building and walked right up the stairs until he got to a very narrow passage that led to a door which led out onto the roof of the building.  The old man led his son to the edge of the roof and said "Right, son.  Today you're going to learn the most important thing that you'll ever need to know in this business."

"And what's that?" replied his son.

"In order to find out you need to jump off of the roof" replied the young man's father.

"Are you serious?" replied his son. "It's a twenty foot drop!"

"Son, you do want to take over the family business when I retire, don't you?" said the old man.

"Yes, of course I do" replied his son.

"And you trust me?" asked the old man.

"Of course I do" replied the old man's son. "You're my father."

"Right" said the old man.  "Then do as I say - jump!"

And with that his son jumped off of the roof, only to crash painfully to the ground twenty feet below.  His father rushed down the stairs and out into the car park, where his son was lying on the ground, bruised, battered and winded.

"Son, can you hear me?"  asked the old man.  "Are you OK?"

"Get an ambulance" moaned the old man's son.  "I can't get up."

"Well, there you go, son" replied the old man.  "You've just learned the first lesson in the business - never trust anybody!"