früher zugeschrieben Reinhard Keiser St. Marc Passion

It’s complicated. The author’s inscription “R. Keiser” is found only on the cover of a St Matthew Passion (!), which today contains the St Mark Passion; however the initial R isn’t original, but the result of a correction; similarly the description “Matthaeum” (as in the Passion of St Matthew) was only corrected to “Marcum” (of St Mark) at a later date, probably by a nineteenth-century owner of the manuscript. This allows for a variety of interpretations. Reinhard Keiser can’t realistically be considered the composer of the St Mark Passion; stylistically and biographically, this does not fit at all. Possibly the composer was Gottfried Keiser (Reinhard's father - and the "G" could have been later changed to the "R" for the much better-known Reinhard). As we do not know whether the cover has anything to do with the St Mark Passion at all, Nicolaus Braun (cantor at Hamburg Cathedral) could also be a possibility. He performed the piece several times, but did not identify himself as its composer in the surviving text booklets. Gottfried Keiser, on the other hand, probably composed for Braun several times (which does not mean that the Passion was necessarily written by him). We simply do not know. There is a detailed summary of the source and attribution problems in the edition "Kaiser". Markus Passion als Pasticcio von Johann Sebastian Bach (Leipzig um 1747) mit Arien aus Georg Friedrich Händels "Brockes-Passion" ("Kaiser”. The St Mark Passion as a pastiche of Johann Sebastian Bach [Leipzig, ca. 1747] with arias from George Frideric Handel's "Brockes-Passion"), ed. by Christine Blanken, Stuttgart 2012 (Edition Bach-Archiv Leipzig), Carus 35.502.