The personal intimate spirit from which the reform drew life, however, found an expression in music. To the congregation was allotted a greater or less portion of song. It will be remembered that the early Christians sang together and that not until the seventh century was the privilege taken from them and restricted only to a trained choir. The German people, as a matter of fact, seem never to have quite given up their share in the musical part of the service. At some of the great festival services they joined in the _Kyrie_ and in the _Alleluia_, and very early it became the custom to insert German verses in the liturgy at these places. Thus there developed a literature of German hymns, sometimes partly German and partly Latin, as the following old Easter hymn, obviously interpolated in the _Kyrie_: 'Christ ist erstanden Von der Marter alle. Des sollen wir alle froh sein, Christ soll unser Trost sein, Kyrioleis. Hallelujah, Hallelujah, Hallelujah! Des sollen wir alle froh sein, Christ soll unser Trost sein, Kyrioleis.’ In connection with the mystery plays other hymns were written, such as the following cradle-song, part German, part Latin and part nonsense: 'In dulci jubilo Nun singet und sei froh. Unser’s Herzens Wonne Liegt in præsipio, Und leuchtet als die Sonne. Matris in gremio. Alpha et O. Alpha et O.’ About these hymns there was woven a sort of religious folk music. By the time of the Reformation there was a whole literature to draw from and Luther needed only to organize and standardize many of the hymns which had been familiar to the people for generations. To these he added others of his own writing. The music was drawn from all sources, practically none was especially composed. Luther had to aid him in compiling his hymn-book two famous musicians, Konrad Rupff and Johann Walther. In 1524 these two men were his guests for a period of three weeks. Köstlin[114] writes: 'While Walther and Rupff sat at the table bending over the music sheets with pen in hand, Father Luther walked up and down the room, trying on his fife to ally the melodies that flowed from his memory and his imagination with the poems he had discovered, until he had made the verse melody a rhythmically finished, well-rounded, strong, and compact whole.’ Here we have a picture of the German hymn-tune, later called the _chorale_, in the process of crystallization.