human
So it must have been written before 1715, the date of the Duke's death. Bach was not the only one to make these transcriptions; Mattheson tells us (_Das beschützte Orchester_):
gpt
Compositions of this order (_concerti grossi_, _sinfonie in specie_, overtures) may also be played upon a polyphonic instrument, for instance upon the organ or harpsichord; a few years ago the celebrated S. de Graue, the blind organist of the new Dunes Church in Amsterdam, played from memory and with remarkable clearness in my presence, upon the excellent organ in his church, the latest Italian sonatas and concertos in three and four parts.