Proof

A man went to his lawyer and told him, "My neighbor owes me $500 and he won't pay up. What should I do?"

"Do you have any proof he owes you the money?" asked the lawyer.

"Nope," replied the man.

"Okay, then write him a letter asking him for the $1000 he owed you," said the lawyer.

"But it's only $500," replied the man.

"Precisely. That's what he will reply and then you'll have your proof!"