Profile: Warren Buffett
At 81 years of age, investor Warren Buffett is one of the richest men in the world, with a personal fortune of nearly $40bn.
Recently, Mr Buffett ran a small tax survey in his Omaha office to find out what proportion of everybody's salary was being taxed.
He discovered that he was paying a much lower share of his income in tax than his much lower paid staff. So he proposed that America's tax laws be changed so that he and his "mega-rich friends" pay more income tax.
President Obama has included the "Buffett Rule" in his deficit reduction plan to increase taxes on America's most wealthy.
For BBC Radio 4's Profile Mary Ann Sieghart talks to family, friends and Buffett experts to get an insight into the man known as the "Oracle of Omaha".