PREFACE.I publish the history of the Reformation in advance of the concluding volume on the Middle Ages, which will follow in due time.The Reformation was a republication of primitive Christianity, and the inauguration of modern Christianity. This makes it, next to the Apostolic age, the most important and interesting portion of church history. The Luther and Zwingli celebrations of 1883 and 1884 have revived its memories, and largely increased its literature; while scholars of the Roman Church have attempted, with great ability, an ultramontane reconstruction of the history of Germany and Europe during the period of the Reformation. The Cultur-Kampf is still going on. The theological battles of the sixteenth century are being fought over again in modern thought, with a slow but steady approach to a better understanding and filial settlement. Protestantism with its freedom can afford to be fair and just to Romanism, which is chained to its traditions. The dogma of papal infallibility is fatal to freedom of investigation. Facts must control dogmas, and not dogmas facts. Truth, the whole truth, and nothing but the truth, is the aim of the historian; but truth should be told in love (Eph. 4:15).The signs of the times point to a new era in the ever onward March of Christ's kingdom. God alone foreknows the future, and sees the end from the beginning. We poor mortals know only "in part," and see "in a mirror, darkly." But, as the plans of Providence unfold themselves, the prospect widens, old prejudices melt away, and hope and charity expand with our vision. The historian must be impartial, without being neutral or indifferent. He must follow the footsteps of Divine Providence, which shapes our ends, and guides all human events in the interest of truth, righteousness, and peace.I have collected much material for a comprehensive history of the Reformation, in the libraries of Europe, during several summer visits (thirteen in all), and digested it at home. I have studied the Luther literature in Berlin, the Zwingli literature in Zuerich, the Calvinistic literature in Geneva and Paris, the English and Scotch Reformation in London, Oxford, and Edinburgh. Two years ago I revisited, with great satisfaction, the classical localities made memorable by the Reformation,--Wittenberg, Eisleben, Eisenach, the Wartburg, Halle, Leipzig, Jena, Weimar, Erfurt, Gotha, Heidelberg, Zuerich, Geneva,--and found kind friends and Christian brethren everywhere. At Marburg, Coburg, Augsburg, I had been before. By way of contrast I made in the same year an interesting tour through Roman-Catholic Spain, the land of Ferdinand and Isabel, Charles V., Philip II., and Ignatius Loyola, and compared her former and present state with the Protestant North. In Italy I have been three times, including a three-months sojourn in Rome. A visit to the places of events brings one nearer to the actors, and puts one almost into the position of a witness.This volume embraces, besides a general introduction to modern church history, the productive period of the German Reformation, from its beginning to the Diet of Augsburg (1530), and the death of Luther (1546), with a concluding estimate of the character and services of this extraordinary man. I have used the new Weimar edition of his works as far as published; for the other parts, Walch and the Erlangen edition. Of modern Protestant historians I have chiefly consulted Ranke (my teacher), and Koestlin (my friend), with whose views, on Luther and the Reformation I am in essential harmony.