The 'crisis of church and state' that began in the second half of the eleventh century is argued here as having fundamentally reshaped European patterns of state formation and regime change. It did so by doing away with the norm in historical societies - sacral monarchy - and by consolidating the two great balancing acts European state builders have been engaged in since the eleventh century: against strong social groups and against each other.
The book traces the roots of this crisis to a large-scale breakdown of public authority in the Latin West, which began in the ninth century, and which at one and the same time incentivised and permitted a religious reform movement to radically transform the Catholic Church in the period from the late tenth century onwards.
Drawing on a unique dataset of towns, parliaments, and ecclesiastical institutions such as bishoprics and monasteries, the book documents how this church reform movement was crucial for the development and spread of self-government (the internal balancing act) and the weakening of the Holy Roman Empire (the external balancing act) in the period AD 1000-1500.