services of the two most important churches in Leipzig, St. Thomas and St. Nicholas. As can be seen below, the work was only performed in its entirety at the St. Nicholas Church. First performances: 25 December 1734: Part I – 'early in the morning' at St. Nicholas; 'in the afternoon' at St. Thomas 26 December 1734: Part II – morning at St. Thomas; afternoon at St. Nicholas 27 December 1734: Part III – morning at St. Nicholas 1 January 1735: Part IV – morning at St. Thomas; afternoon at St. Nicholas 2 January 1735: Part V – morning at St Nicholas 6 January 1735: Part VI – morning at St. Thomas; afternoon at St. Nicholas Text The ease with which the new text fits the existing music is one of the indications of how successful a parody the Christmas Oratorio is of its sources. Musicologist Alfred Dürr and others, such as Christoph Wolff have suggested that Bach's sometime collaborator Picander (the pen name of Christian Friedrich Henrici) wrote the new text, working closely with Bach to ensure a perfect fit with the re-used music. It may have even been the case that the Christmas Oratorio was already planned when Bach wrote the secular cantatas BWV 213, 214 and 215, given that the original works were written fairly close to the oratorio and the seamless way with which the new words fit the existing music. Nevertheless, on two occasions Bach abandoned the original plan and was compelled to write new music for the Christmas Oratorio. The alto aria in Part III, "Schließe, mein Herze" was originally to have been set to the music for the aria "Durch die von Eifer entflammten Waffen" from BWV 215. On this occasion, however, the parody technique proved to be unsuccessful and Bach composed the aria afresh. Instead, he used the model from BWV 215 for the bass aria "Erleucht' auch meine finstre Sinnen" in Part V. Similarly, the opening chorus to Part V, "Ehre sei dir Gott!" was almost certainly intended to be set to the music of the chorus "Lust der Völker, Lust der Deinen" from BWV 213, given the close correspondence between the texts of the two pieces. The third major new piece of writing (with the notable exception of the recitatives), the sublime pastoral Sinfonia which opens Part II, was composed from scratch for the new work. In addition to the new