During the 16th century close to 30 German dukes, landgraves, margraves and counts, plus one Holy Roman emperor, were known as mad - so mentally disordered that serious steps had to be taken to remove them from office or to obtain medical care for them. This book is the first to study these princes, and a few princesses, as a group and in context. The result is a flood of new light on the history of Renaissance medicine and of psychiatry, on German politics in the century of Reformation, and on the shifting Renaissance definitions of madness.