In works on the Thirty Years War, few phrases appear with such predictable regularity as 'religion and polities'. The close relationship between confessional affiliation and the formulation of policy, both domestic and foreign, is particularly obvious in European history between the Lutheran Reformation and the beginning of the eighteenth century, yet few historians of the period seem to be able to understand, much less explain, it. The problem is central to the historiography of the Thirty Years War, as the motives of the participants appear to vacillate between the loftiest religious ideals and the basest worldly ambitions. At times, historians of the conflict have created a dichotomy between 'religious' and 'political' motives that leaves little room for manoeuvre between the two.