Two years before this (1524) he had published the first Protestant hymn-book (_Geystliche Gesangk Buchleyn_, for four voices), with the assistance of his friend and musical adviser, Johann Walther. In 1525 Walther published another and larger one, with a preface by Luther. Chorale-books now multiplied with such astonishing rapidity that at the time of Luther’s death in 1546 there were no less than sixty collections in use, including the various editions. The very first hymn-melodies sung by the congregation were not harmonized at all. Soon simple contrapuntal settings were given to these melodies, and in all the early chorale-books the melody, following the contemporary usage in contrapuntal writing, was placed in the tenor, the congregation singing it in unison while the choir supplied the contrapuntal parts. But by the end of the sixteenth century harmonic feeling had progressed far enough to permit the melody to pass to the treble,[45] where it naturally belonged in the people’s song. Henceforth it is generally found there, supported by solid chord-movement, and its early contrapuntal character becomes transformed into a simpler harmonic style. The development of the organ in Germany during the closing decades of the sixteenth century made it possible for this instrument to take the place of the choir as an accompaniment to the unison congregational song, the choir after 1600 finding ample scope for its powers in the elaborate motet. The brutal devastation of the Thirty Years’ War was followed by a weakening of religious faith and vigor, and after the middle of the seventeenth century interest in the chorale waned and the steady stream of chorales slackened and soon came to a full stop. The sturdy militant enthusiasm of the early years of the Reformation was superseded by religious apathy which had a corresponding influence on church music. The rhythmical freedom and variety of the early chorales gradually disappeared and their vigorous character became tamed down to the type as now sung, in which the tones of the melody assumed a uniform length. While this style is undoubtedly dignified and imposing, it represents a distinct loss of energy and vigor, as compared with the original free form. But the chorale had already passed into the larger arteries of German secular art-music, and here its tremendous powers of stimulation were no longer dependent on the spiritual pulse of the church.