On the occasion of Hagen Keller's 80th birthday, former collaborators have discussed how political history of the Middle Ages must always be rewritten in the field between fragmented tradition, historiographical findings and modern social discourses. In this way, the contributions document not only the breadth of topics to which Hagen Keller's œuvre has provided substantial impulses, but also an autoreflexive, problem-focused line of thought that has shaped the cooperation with him.