This book is essentially addressed to a single question arising from the intricate political history of the medieval western Empire: why did Germany evolve into a multiplicity of autonomous states under secular dynasties, urban authorities, and prince-bishops, becoming a species of aristocratic congeries in which the crown enjoyed enormous prestige but minimal authority? In my view, one answer to this is to be found not in the realm of high politics, but in the vigorous consolidation of princely jurisdictions in the German regions, a complex process which took significant new directions between the later eleventh and the earlier fourteenth centuries. The aim of the book is to examine those directions, and to try to uncover the causes for them. This pursuit involves the study of Germany's political and juridical institutions in the Middle Ages, but the threatening aridity of such an approach is, I hope, tempered by delineations of the princes and dynasties, churchmen, and kings whose careers actually gave life to those institutions. It has clearly to be stated that there is no intention of serving up a ‘total history’ of the medieval German aristocracy. The material to be presented concerns aristocratic politics, princely and episcopal territories, and highly placed persons. There is nothing here about the cultural background and achievements of the German princes and their courts as centres of patronage and creativity in many of the arts, a huge subject with rich sources of its own. There is not much social and economic history of the nobility as a class or order either, although the changing structure of their families is discussed in chapter 8 and the economic foundations of their regional power is outlined in chapter 9.