Continuation of Andrew Carnegie "Power of Persuasion"

Carnegie drafted his letter to his nephew and signed it and then added a post script that he was enclosing a check for $10. But he did not put in the $10 check. Shortly thereafter he received a reply from his nephew stating the check was not enclosed in the letter he received from his uncle. Carnegie showed the letter to his sister who paid off her debt to her brother. Andrew Carnegie then sent the $10 to his nephew.

Of course, one hopes they never need to trick loved ones into communicating with them. But if you ever need to persuade someone to do something a certain way, remember that self-interest is one of the most effective motivators.