The St. John Passion ranks among the great vocal works from Bach's Leipzig years. In contrast to his other large-scale choral works, however, Bach never gave this work a definitive final form. Rather, for every performance he made numerous changes. All previous editions of the St. John Passion have combined readings from various layers of sources. The wish often expressed by conductors to perform an authentic version is made possible for the first time with the present edition in this fourth and final version which was performed under Bach's direction in 1749. At the same time, with the aid of the appendix it is possible to perform the work in the traditional "mixed version."