title, "Schriften des Vereins fuer Reformationsgeschichte," which have been exceptionally well introduced by Kolde's writing, "Luther und der Reichstag zu Worms, 1521" (Halle, 1883). All of them deal directly with Luther, or with movements caused by his lifework.
Janssen gave a real and unmistakable impetus to research work on Luther among men of learning. Prepared to work in a scientific manner by accepting Ranke's methods in the field of church history, they were forced by Janssen to begin. Added to this, Janssen's lifework not only was taken up by other Catholic theologians, continued and its scope widened,'7 but a later book by Denifle, "Luther und Luthertum in der ersten Entwicklung quellenmaessig dargestellt" (Ist vol. Ist ed. 1904; 2nd vol. ed. by A. M. Weiss, 1909), also raised new questions and demanded a more thorough study, especially of the pre-Reformation theology. The latest Catholic work on Luther, by H. Grisar (Martin Luther, first volume: Luther's Werden, second volume: Auf der Hoehe des Lebens, 1911, third volume: Am Ende der Bahn, 1912), had much less influence on Protestant research into the life of Luther.
Subordinated to these two main factors, there are two further circumstances that were of material assistance. In the first place, Protestant theology was given the great book on Luther, by Julius Koestlin: "Martin Luther; Sein Leben und seine Schriften," in 1875, and in 1883 this work appeared in its second edition vastly improved. Koestlin did not belong to the Rankean school. He was not a church historian, but a systematician. He did not study the old sources in the manner of the historians of this school, when he began his work; and even later he rarely co-operated in the search for new material, that
