A new century awaits, and with it new conflicts.

We have answered so many astonishing questions in the century now ending--Can we put a man on the moon? How do atoms work?--that the unanswerable rankles a bit. But mysteries endure, and even after a century of Roosevelts, peppered with a Gorbachev and a Mandela and a Churchill, we are no closer to an answer for the greatest of historical questions: Where do leaders come from?

It's a lively question as we gaze at the pink morning of a new century, a question that vibrates with possibility and that engages both our hopes and fears: Who will be the Gorbachev of...