2. The important ought to be distinguished from the unimportant at every step. Athanasius and Augustine are worthier subjects of study than Flavian and Optatus. The invasion and conversion of the Teutons are more important than disputes over Easter or the shape of the tonsure. 3. Original sources ought to be used so far as possible. History should be studied "from the sources of friend and foe, in the spirit of truth and love, _sine ira et studio_."[9:1] 4. Both Protestant and Catholic secondary authorities ought to be read on every important controverted point. 5. Origins ought to be studied with special care. 6. Transition periods rather than crises ought to be given the most time. 7. Biographies of epoch-making men like Constantine, Gregory the Great, Charlemagne, Hildebrand, St. Francis, Innocent III., etc., ought to be carefully considered. 8. Causes and results ought to be closely worked out and classified.[9:2] 9. The continuity of the Church as a great force in the world ought to be ever kept in mind.[9:3] 10. Differentiation ought to be thoughtfully noted through the ages. 11. The unity of history--the influence of the Church upon every other institution--ought to be followed from one transitional period to another. 12. The sympathetic attitude ought to be taken at all times in judging men and movements. The student ought to stand in the centre of the circle so that he may see all points of the circumference--all persons, all events, all parties, all creeds, all sects, all shades of opinion--and see their true historical relations. SOURCES 1.--Bright, W., _The Study of Church History_. In _Waymarks of Church History_. N. Y., 1894. 2.--Cave, A., _Introduction to the Study of Theology_. Edinb., 1885, 421 _ff._ 3.--Collins, W. E., _The Study of Ecclesiastical History_. N. Y., 1903. 4.--Coxe, A. C., _Institutes of Christian History_. Chicago, 1887. 5.--De Witt, J., _Church History as a Science, as a Theological Discipline, and as a Mode of the Gospel_. Cinc., 1883. 6.--Foster, F. H., _The Seminary Method of Original Study in the Historical Sciences_. N. Y., 1888. 7.--Gwatkin, H. M., _The Meaning of Ecclesiastical History_. Camb., 1891. 8.--Hatch, E., _An Introductory Lecture on the Study of Ecclesiastical History_. Lond., 1885. 9.--Hitchcock, R. D. _The True Idea and Uses of Church History_. N. Y., 1856. 10.--Jortin, J., _The Use and Importance of Ecclesiastical History_. _Works_, vii., 405-454. Lond., 1772. 11.--Lea, H. C., _Studies in Church History_. Introd. Phil., 1869. 12.--McGiffert, A. C., "The Historical Study of Christianity." _Bibliotheca Sacra_, Jan., 1893, 150-171. 13.--Robinson, J. H., _Sacred and Profane History_. In _An. Rep. Am. Hist. Assn._ 1899, i., 527.