The St. Mark Passion, which probably originated in the first decade of the 18th century, by a composer known until now only as "Kaiser," is only preserved in various copies. It occupies a prominent place in Bach’s music library as the only music for Passion by another composer which he performed several times, usually in different forms. For the young Bach in Weimar this St. Mark Passion was a didactic piece for learning the art of the modern narrative recitative; as the Leipzig Thomaskantor he also performed it (1726). The present edition reconstructs the third version, first performed in Leipzig (1747), in which Bach inserted seven arias from Handel's famous BrockesPassion. Only in this pasticcio did a direct encounter occur between him and his famous compatriot in London, a real encounter which Bach longed for, but which never came about.