““For more than a thousand years this idea of the unity of Christendom, of Christendom as a sort of vast Amphictyony, whose members even in war time were restrained from many extremities by the idea of a common brotherhood and a common loyalty to the Church, dominated Europe. The history of Europe from the fifth century onward to the fifteenth is very largely the history of the failure of this great idea of a divine world to realize itself in practice. The””