The union of all Christians and the restoration of primitive Christianity were the two main ideas announced by Thomas Campbell in his _Declaration and Address_ in 1809 and championed by Alexander Campbell for fifty years thereafter. With some differences of emphasis and phrasing, they were the ruling ideas of Stone and the other reformers whose work preceded, paralleled, and reinforced his. To this day, these are the two foci of interest among Disciples, and every difference of opinion which threatens to create parties among them revolves about answers to the questions: “Restoration of what?” and “What price union?” Each of these ideas, union and restoration, has a long history, only a small part of which can be told here, but part of which must be told. The Idea of Union The essential unity of the church was and is a basic principle of Roman Catholicism. It was a formative idea in the Catholic Church of the second and third centuries, which had not yet become Roman, and it continued to be so through all the history of the imperial church of the Middle Ages. The great Protestant reformers of the sixteenth century did not cease to be “catholic” in their belief that the church was divinely intended to be one body. They wanted to reform the church, not to break it into pieces. Efforts to heal the breach with Rome were long continued and frequently renewed. But reunion with Rome proved to be impossible on any other terms than submission to that usurped authority from which they had revolted. Different types of Protestantism soon appeared. The principal varieties—Lutheranism, Calvinism, Zwinglianism, Anabaptism, episcopal Anglicanism—represented, not divisions of an originally united Protestantism, but separate and independent revolts from Rome. Among these there was a long series of conferences, negotiations, and proposals designed to unite, if possible, all Protestants into one body. Such efforts continued to be made throughout the seventeenth century.