§ 2.1. =The Various Branches Included in a Complete Course of Church History.=--The Christian Church has undertaken the task of absorbing all peoples and tongues. Hence it is possessed of an eager desire to enlarge its borders by the conversion of all non-Christian races. The description of what helps or hinders this endeavour, the history of the spread and limitation of Christianity, is therefore an essential constituent of church history. Since, further, the church, in order to secure its continued existence and well-being, must strive after a legally determined position outwardly, as well as a firm, harmonious articulation, combination and order inwardly, it evidently also belongs to our science to give the history of the ecclesiastical constitution, both of the place which the church has in the state, and the relation it bears to the state; and also of its own internal arrangements by superordination, subordination, and co-ordination, and by church discipline and legislation. Not less essential, nay, even more important for the successful development of the church, is the construction and establishment of saving truth. In Holy Scripture the church indeed has possession of the fountain and standard, as well as the all-sufficient power and fulness, of all saving knowledge. But the words of Scripture are spirit and life, living seeds of knowledge, which, under the care of the same Spirit who sows them, may and shall be developed so as to yield a harvest which becomes ever more and more abundant; and therefore the fulness of the truth which dwells in them comes to be known more simply, clearly, fully, and becomes always more fruitful for all stages and forms of culture, for faith, for science, and for life. Hence church history is required to describe the construction of the doctrine and science of the church, to follow its course and the deviations from it into heresy, whenever these appear. The church is, further, in need of a form of public worship as a necessary expression of the feelings and emotions of believers toward their Lord and God, as a means of edification and instruction. The history of the worship of the church is therefore also an essential constituent of church history. It is also the duty of the church to introduce into the practical life and customs of the people that new spiritual energy of which she is possessor. And thus the history of the Christian life among the people comes to be included in church history as a further constituent of the science. Further, there is also included here, in consequence of the nature and aim of Christianity as a leaven (Matt. xiii. 33), an account of the effects produced upon it by the development of art (of which various branches, architecture, sculpture, painting, music, have a direct connexion with Christian worship), and likewise upon national literature, philosophy, and secular