During the sixteenth century close to thirty German dukes, landgraves, 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 study these princes, and a few princesses, as a group in context. The result is a flood of new light on the history of Renaissance medicine and of psychiatry, on German politics and in the century of Reformation, and on the shifting Renaissance definitions of madness.