Since the 19th century, a violin concerto model has been suggested for Bach's first Harpsichord Concerto, BWV 1052: the violin concertos resulting from various reconstruction attempts seem to indicate, at least according to Peter Wollny, that for this harpsichord concerto there was likely no violin concerto model. From the second half of the 20th century, there were several attempts to reconstruct the St Mark based on extant material from Bach's music library. Bach's two surviving Passions ( St Matthew and St John) are among the composer's most often performed vocal works, and Bach's most popular oratorio, the Christmas Oratorio, written in the early 1730s like the St Mark Passion, was apparently to a large extent based on earlier compositions by Bach: a similar assumption was made for the St Mark. Ī more elaborate undertaking was the reconstruction of Bach's lost St Mark Passion, BWV 247: its libretto, printed in 1732, survived without music. Reconstructions of BWV 1060 to its presumed original version, published from the 1920s, extended the Bach repertoire for oboists. For instance, in the late 19th century it was discovered that Bach likely transcribed his Concerto for two harpsichords in C minor, BWV 1060, from a lost earlier version for violin and oboe. Reasons for such reconstructions include extension of the repertoire and testing hypotheses about the genesis history of known pieces. Lost versions of compositions by Johann Sebastian Bach can be reconstructed on the basis of extant versions of similar music.