as follows: The Mass in B minor is the consecration of a whole life: started in 1733 for "diplomatic" reasons, it was finished in the very last years of Bach's life, when he had already gone blind. This monumental work is a synthesis of every stylistic and technical contribution the Cantor of Leipzig made to music. But it is also the most astounding spiritual encounter between the worlds of Catholic glorification and the Lutheran cult of the cross. Scholars have suggested that the Mass in B minor belongs in the same category as The Art of Fugue, as a summation of Bach's deep lifelong involvement with musical tradition—in this case, with choral settings and theology. Bach scholar Christoph Wolff describes the work as representing "a summary of his writing for voice, not only in its variety of styles, compositional devices, and range of sonorities, but also in its high level of technical polish ... Bach's mighty setting preserved the musical and artistic creed of its creator for posterity." The Mass was described in the 19th century by the editor Hans Georg Nägeli as "The Announcement of the Greatest Musical Work of All Times and All People" ("Ankündigung des größten musikalischen Kunstwerkes aller Zeiten und Völker"). Despite being seldom performed, the Mass was appreciated by some of Bach's greatest successors: by the beginning of the 19th century Forkel and Haydn possessed copies. Autographs and editions Two autograph sources exist: the parts for the Kyrie and Gloria sections that Bach deposited in Dresden in 1733, and the score of the complete work that Bach compiled in 1748–50, which was inherited by C.P.E. Bach (the autograph has been published in facsimile from the source in the Staatsbibliothek zu Berlin). However, for his 1786 public performance of the Symbolum Nicenum, C.P.E. Bach, as was typical practice in the era, made additions to the autograph score for performance by adding a 28-bar introduction, replacing the now-obsolete oboe d'amore with newer instruments (clarinets, oboes, or violins) and making other changes in instrumentation for his own aesthetic reasons. C.P.E. also wrote in his own solutions to reading some passages made nearly illegible by his father's late-life handwriting problems. For this and other reasons, the Mass in B minor poses a considerable challenge to prospective editors, and substantial variations can be noted in different editions, even critical urtext editions. The Bach Gesellschaft edition, edited by Julius Rietz, was