Keith Jarrett improvised the best-selling solo piano performance of all time, and so did the 18-year-old girl who scrambled to put the show together. Keith Jarrett is an American jazz pianist and composer renowned for his virtuosic improvisational performances, most famously the one that flowed through his fingers at the Opera House in Cologne on the night of January 24, 1975 — the recording of which remains the best-selling solo album in the history of jazz and piano. By flouting all