two times four = a high pitched whoah, whoaahhh!

(above)This is Vivaldi's Concerto for four violins in b minor.
(below) Bach's Concerto for four harpsichords in a minor

These blew me away today and I heard them back to back on the way home from work.  The first piece played,Vivaldi's, made me smile (once I turned it up to the appropriate volume) then I was blessed to hear the harpsichord interpretation.  Now, I love harpsichords so this made me double happy.  They are amazing.

The story is that a wealthy prince let Bach hand copy the Vivaldi sheet music and this is where Bach got the inspiration to 'cover' the piece.  He added more movement within it by sprucing it up with added notes because the harpsichord cannot sustain notes like the violin can.  I heard this explanation on NPR or WMNR Fine Arts Radio.  I don't remember the man's name who's show was on.