Karl Miller wrote:

>What about Bach's arrangements of Vivaldi Concerti, Stokowski orchestrating
>anybody, Casella rearranging Scarlatti and Paganini, Schoenberg rewriting
>Monn, etc.?

I think that you are confusing "arrangement" with "transcription" here.
An arrangement often completely alters notes and harmonies.  Take a simple
example of the Christmas Carol "Silent Night" as found in your hymnal as
compared to the "arrangement" by the Swedish vocal ensemble, The Real
Group.  Although the tune remains the same, everything else is different.

The examples you cite above do not alter the composer's original works,
except to make them playable on instruments other that what was originally
intended.  (Bach's transcription of Vivaldi's violin concerti for
harpsichord, Stokie's transcription of Bach's organ fugues for orchestra,
for example.

It is a subtle difference, but a real one I believe.

Kevin