In 1790 Thomas Jefferson penned in a letter to James Madison his famous idea that "the Earth belongs to the living." With intricate mathematical calculations he determined the span of generations and reasoned that since present generations should not be bound by the decisions and compacts of past generations, all laws should expire every 19 years. Madison responded with a gentle -- but devastating -- counter, pointing out to his friend the practical problems with this idea and concluding that its implementation, by causing so much uncertainty in the continuity of arrangements, would be enormously harmful. For most of our...