science generally; and also, conversely, an estimate of the influence of these forms of secular culture upon the condition of the church and religion must not be omitted. The order of succession in the historical treatment of these phases under which the life of the church is manifested, is not to be rigidly determined in the same way for all ages after an abstract logical scheme. For each period that order of succession should be adopted which will most suitably give prominence to those matters which have come to the front, and so call for early and detailed treatment in the history of that age. § 2.2. =The Separate Branches of Church History.=--The constituent parts of church history that have been already enumerated are of such importance that they might also be treated as independent sciences, and indeed for the most part they have often been so treated. In this way, not only is a more exact treatment of details rendered possible, but also, what is more important, the particular science so limited can be construed in a natural manner according to principles furnished by itself. The history of the spread and limitation of Christianity then assumes a separate form as the History of Missions. The separate history of the ecclesiastical constitution, worship, and customs is known by the name of Christian Archæology, which is indeed, in respect of title and contents, an undefined conglomeration of heterogeneous elements restricted in a purely arbitrary way to the early ages. The treatment of this department therefore requires that we should undertake the scientific task of distinguishing these heterogeneous elements, and arranging them apart for separate consideration; thus following the course of their development down to the present day, as the history of the constitution, of the worship, and of the culture of the church. The history of the development of doctrine falls into four divisions: a. The History of Doctrines in the form of a regular historical sketch of the doctrinal development of the church. b. Symbolics, which gives a systematic representation of the relatively final and concluded doctrine of the church as determined in the public ecclesiastical confessions or symbols for the church universal and for particular sects: these again being compared together in Comparative Symbolics. c. Patristics, which deals with the subjective development of doctrine as carried out by the most distinguished teachers of the church, who are usually designated church Fathers, and confined to the first six or eight centuries.