Quick by the way- the chronology of Chopin's preludes was the subject of an August 1957 article in the British magazine the Musical Times by Maurice J.E. Brown; on the scanned-in copy of this article (accessible to students/faculty/staff- I'm the last-named) - I'm basing my estimates of the dates of composition of the preludes... I'm not entirely a-ret. but I like writing down the information if I can get it. *gryn*
