From Roman times to the twentieth century the relationship between the Church and the secular state has varied from harmony to open dissension, from virtual identity of aims to uneasy truce. Douglas Woodruff, writing especially for this series, surveys and analyses the changing character of Church-State relations beginning with the Roman persecutions and the consequences of the dramatic change wrought by Constantine's adoption of Christianity as the imperial religion. From this union of Church and State developed the tension extending through the feudal age and the development of Christendom which arose out of the resistance of the Popes to attempts by Kings and Emperors to use the Church to further their own ends. Douglas Woodruff goes on to trace the emergence in the Later Middle Ages of national states, the final break-up of Christendom at the Reformation and the succeeding age of the Absolutist Hapsburg and Bourbon monarchs. He concludes his survey with two chapters discussing the Church confronted with an age of revolution and the hostility of the totalitarian systems together with the development of the tradition of the Church as one voluntary society within a plural society.