Another significant aspect of the Mercersburg Theology is the view of history and theology found in Philip Schaff's "Principle of Protestantism." In this work, Schaff takes a Hegelian model of history and applies it to the history of theology. Theology must come to one final synthesis, as Schaff expressed in his remark that "the Reformation must be regarded as still incomplete. It needs yet its concluding act to unite what has fallen asunder, to bring the subjective to a reconciliation with the objective." By this, he proposes a reunion of the subjective doctrines of Protestantism with the objective character of the Roman Catholic Church. Thus, an outworking of this belief is a generous ecumenism extended toward all, especially toward Roman Catholics. Another contributor to the Hegelian approach of Mercersburg Theology was Friederich Augustus Rauch, especially through his work "Psychology".