AP Photo

When Joseph Ratzinger was chosen by his fellow cardinals to be pope in April 2005, he was universally billed as the continuity candidate. He had spent 25 years doing John Paul II’s bidding in charge of the old Holy Office, and most Catholics believed they knew exactly what Benedict XVI stood for. Few expected any surprises. Yet now he has pulled off the biggest surprise of all by becoming the first pope in 600 years to resign.