Arthur is 90 years old. He's played golf every day since his retirement 25 years ago. One day he arrives home looking downcast. "That's it," he tells his wife. "I'm giving up golf. My eyesight has become so bad that once I hit the ball I couldn't see where it went." His wife sympathises and makes him a cup of tea. As they sit down she says, "Why don't you take my brother with you and give it one more try."
"That's no good" sighs Arthur, "your brother's a hundred and three. He can't help."
"He may be a hundred and three", says the wife, "but his eyesight is perfect."
So the next day Arthur heads off to the golf course with his brother-in-law. He tees up, takes a mighty swing and squints down the fairway.
He turns to the brother-in-law and says, "Did you see the ball?"
"Of course I did!" replied the brother-in-law. "I have perfect eyesight".
"Where did it go?" says Arthur.
"I don't remember."