Very little is known of the precise origins of this Bach organ work in the key of F major, BWV 590, which is usually known as the "Pastorale" in F, and sometimes Pastorella in some sources. It comprises of four sections, and is thought by most scholars to have been written for performance during the Christmas services held at the main Leipzig churches with which Bach was closely associated. The work was therefore written presumably around the year 1720. No autograph copy has survived, nor is there any plausible indication of how the work might have fitted into the Christmas liturgy, though it is now regarded as definitely Bach's work, having been long-disputed due to lack of clearly attributable material.
Without question, however, the emergence of certain galant-style features places the Pastorale late in Bach's career. The most interesting attribute is the use (in each of the first two sections) of "Piffero" or "piping" style, based on the drone bass line and skirling bagpipe melodies widely encountered in Italian Christmas folk music. Even in the late twentieth century, the ancient traditions of bagpipe-playing shepherds processing through small towns have been upheld at Christmas, the idea being that the ritual recalls the shepherds' journey to Bethlehem. Traditional Piffero music usually offers two melodies in canon, normally heard against a drone bass line and entirely based on tonic, subdominant, and dominant harmonies. Interestingly, there are also examples of Piffero technique to be found in the Christmas Oratorio, notably in the Sinfonia preceding Part II, and also in a small number of other Bach works.
The third movement is far more sophisticated and its aria-like theme has a special symbolism. The three-flat key signature and triple meter were often used to represent angels, and the assumption is that here Bach intended to depict the appearance of the angels to the shepherds as recorded in Luke's gospel (2:8-15). The concluding section of the work is a gigue in fugal form, the melody of which has been traced by Christoph Wolff to an early Medieval hymn-tune "Resonet in laudibus," itself often sung at Christmas to portray the shepherds' rejoicing upon finding the infant Jesus. ~ Michael Jameson, All Music Guide
