The chorale prelude to "O Mensch, bewein deine Sünde gross" is written by an unknown "M.W.C.B.M". Written for two manuals and pedals, it has the choral melody in the upper voice. The melody is treated in typical coloratura manner. All the notes of the melody are there, on the right spot, on the right moment. There are also a lot of notes in between, which can make it difficult to discern the actual melody. The embelishments are well crafted and written in a very sensitive way. Though we do not know who the man or woman behind the initials was, it is clear that he or she was an composer organist of great ability. As organists we can count ourselfes lucky a few compositions of this composer survive, so we can still play and enjoy them.