A man was walking along a road one day, when he came to a bridge across a river. Sitting on a large chair right in the middle of the path was a man, dressed in a suit of armour, and holding an enormous sword.

"None Shall Pass!" shouted the knight, in an intimidating voice.

"Why not?" asked the traveller.

"You must tell me why you want to cross the bridge."

"I want to get to the other side."

"Not good enough!" yelled the knight, brandishing his weaponry threateningly.

"Errr, I want to get to the next town," said the man.

"Sorry, but you must give me a good reason, or I can't let you cross."

"Okay. The reason I'm travelling is because I'm visiting my brother, who's sick."

"Hmmm...," said the knight. He pondered on this for a moment, before saying: "okay. That's good enough. I'll let you pass." The knight stood up, and let the man pass.

When the man arrived at his brother's house, he told the story of the knight at the bridge. "I can't understand why he made such a fuss about it," he said.

"It's obvious," said his brother, ......... "It only stands to reason."