I have a question about measure three of Chopin's Prelude in C minor. My book has an editorial comment that Chopin is supposed to have added a flat sign before the last E (G, C, E) in a copy belonging to one of his pupils but that it does not appear in the original. I have mistakenly been playing the E as E flat, and now when I play it E natural, it doesn't sound right and, in fact, sounds better to me as E flat. I've listened to other people play this, and sometimes it seems they're playing E flat instead of E natural. What's the accepted way of playing this? Thanks for your help. It's such a beautiful piece and I want it right.