The Violin Concerto in G minor, BWV 1056a, by Johann Sebastian Bach (1685-1750) is reverse engineered from his Harpsichord Concerto in F minor, BWV 1056. Bach scholars these days believe that almost all his 15 concertos for harpsichord, alone or with other instruments, were reworkings of earlier concertos (by Bach or others) for other instruments.
He seems to have used them as training and performance vehicles for young players. He was in charge of the Leipzig Collegium Musicum during the 1730s, and, with 20 children of his own born over 34 years, always had a young musician or two in his house, so there was no shortage of players to train and show off.
Some of the models from which Bach made his harpsichord concertos are available: extant violin concertos and cantata movements by Bach, or a concerto for four violins by Vivaldi, for example. In other cases the original has been lost. Harpsichord concertos from known originals show that in making the harpsichord arrangement Bach was inclined to use the entire range of the original solo instrument, and did not alter the contours of the solo part significantly when he made the harpsichord version. Thus, by looking at the range required for the solo part, a fair guess can be made about the original solo instrument. On the basis of evidence of this sort, reconstructions have been made, and published in no less authoritative a source than the Neue Bach-Ausgabe as “original” versions of concertos.
The first movement of the G-minor Violin Concerto is marked by two unusual features. The first is that the violin breaks off into short solos during the opening orchestral ritornello. The other is that the soloist is set off from the orchestra rhythmically, with the orchestra playing in straight two-four time and the soloist playing almost exclusively in triplets. The second movement is one of Bach’s bigger hits, perhaps better known, in a version for oboe and strings, as the Sinfonia to the cantata “Ich steh mit einem Fuß im Grabe” (I stand with one foot in the grave), BWV 156.
