Within a few months he left his lair to deliver a series of eight sermons in Wittenberg. Yet the emperor was already gone. Preoccupied by his conflict with the French, he absented himself from central Europe for ten years. By the time he returned, it was too late. Europe had changed. Somewhere in the continent a kind of universal joint—one of those suspicious devices whose design could be found among Leonardo’s papers—had shifted. German princes, the king of France—even the pope—were loath to give Charles the powers he needed to suppress Luther. Moreover,
