It is highly debatable whether Grillparzer (a contemporary of Beethoven and Schubert) knew Bach’s six works for violin solo. Nevertheless he manages in this poem, without actually intending to do so, to go right to their core. It seems as if Bach demands the extremes from the violin, even more than it is capable of.
Was there any violinist during Bach’s lifetime capable of playing them? Maybe Pisendel, the leading German violinist of his time? Or had he intended his solo works for none other than himself? We still aren’t sure, but what is for sure is that Ning Feng would have impressed Bach with his reading of the complicated chords and figurations.