Denifle had for years been studying the history of medieval theology and mysticism, as well as the lives of saints and scholars by whom in both departments progress had been effected, on the other hand his investigations revealed the decadence of ecclesiastical life during the Hundred Years War and caused him to amass documents (about 1200) showing the many abuses then prevalent among the clergy both secular and regular. The contrast was marked. As was his wont he resolved to solve the problem that arose, to see what could have been the result of such moral corruption. These new researches were not confined to France, they gradually extended to Germany. Denifle found proof that in both countries, with praiseworthy exceptions, during the fourteenth century things went from bad to worse, but he saw that the end had not been reached yet. He traced the downward course of profligacy to the third decade of the sixteenth century, and there he stopped for he had found the abyss. Crimes which ecclesiastics and religious were ashamed of in the preceding era now became to one section a cause of self-glorification, and were even regarded as miracles and signs of sanctity. At the beginning of this painful investigation Denifle had not a thought about Luther, but now he saw that he could not avoid him; to estimate the new departure it was necessary to understand Luther, for of this appalling depravity he was the personification as well as the preacher. So Denifle devoted many years to the task of ascertaining for himself how, and why, and when Luther fell. The Vatican archives and various libraries, particularly those of Rostock and Kiel, supplied original documents to which this independent study was confined. As usual Denifle made a series of discoveries. His work, which is divided into three parts, if we take its second edition, is in no sense a biography. The first part is a critique of Luther's treatise on monastic vows. It examines his views on the vow of chastity in detail, and convicts him of ignorance, mendaciousness, etc. The second part which is entitled "a contribution to the history of exegesis, literature and dogmatic theology in the Middle Ages", refutes Luther's assertion that his doctrine of justification by faith, i.e. his interpretation of Rom., I, 17, was the traditional one, by giving the relevant passages from no fewer than sixty-five commentators. Of these works many exist only in manuscript. To discover them it was necessary to traverse Europe; this part which appeared posthumously is a masterpiece of critical erudition. The third part shows that the year 1515 was the turning point in Luther's career, and that his own account of his early life is utterly untrustworthy, that his immorality was the real source of his doctrine, etc. No such analysis of Luther's theology and exegesis was ever given to the learned world for which it was written.
For some time previous it had been known that Denifle was engaged on such a work, but when in 1904 the first volume of 860 pages of "Luther und Luthertum in der ersten Entwicklung quelienmässig darstellt" appeared, it fell like a bomb into the midst of the Reformer's admirers. The edition was exhausted in a month. The leading Protestants and rationalists in Germany, Seeberg, Harnack, and seven other professors, besides a host of newspaper writers attempted to defend Luther, but in vain. Denifle's crushing answer to Harnack and Seeberg, "Luther in rationalistischer und christlicher Beleuchtung" appeared in March, 1904, and two months afterwards he issued a revised edition of the first part of the first volume; the second was brought out in 1905 and the third in 1906 by A. Weiss, O.P. He has the second volume on Lutheranism, for which the author left materials, ready (1908) for the press.
Denifle has been censured by some and praised by others for the tone of this work. Perhaps if it were less indignant the amazing erudition displayed would produce a greater effect. There was no need of hard words in a work, to use the words of Cambridge University when it honoured Denifle, on "Lutherum ab eodem ad fidem documentorum depictum". He has thrown more light on Luther's career and character than all the editors of Luther's works and all Luther's biographers taken together. Denifle wished to offend no man, but he certainly resolved on showing once and for all the Reformer in his true colours. He makes Luther exhibit himself. Protestant writers, he remarks betray an utter lack of the historical method in dealing with the subject, and the notions commonly accepted are all founded on fable. As he pointedly observes: "Critics, Harnack and Ritschl more than others, may say what they like about God Incarnate; but let no one dare to say a word of disapproval about Luther before 1521". Denifle's impeachment is no doubt a terrible one, but apart from some trifling inaccuracies in immaterial points it is established by irrefragable proofs.
Denifle, who was beloved by Leo XIII and Pius X was a conductor of the cardinalitial Commission of Studies, a member of the Imperial Academy of Sciences (Vienna), and of those of Paris, Prague, Berlin, Göttingen, honorary Doctor of the Universities of Münster and Innsbruck, member of the Legion of Honour, of the Order of the Iron Crown, etc. He was on his way to Cambridge, where he and his friend Father Ehrle were to be made Honorary Doctors of that university, when he was struck down by the hand of death.
1 -[Heinrich Suso]
2 -[Heinrich Suso : His research]
3 -[Heinrich Suso : theology and mysticism]
Source : REGINALD WALSH, Transcribed by Albert Judy, O.P. in http://www.newadvent.org