Chopin thought the first two bars were too much like Beethoven's masterwork the "Moonlight Sonata," therefore, he did not have it published. It was written in 1824 and one of his pupils published the work against the composer's wishes. It is now considered one of the greatest and most popular works among piano students for it's polyrhythm, which leads to a beautiful legato middle section. I guess he considered destroying the piece because he didn't want to be plagiarizing Beethoven. If you listen Beethoven measure 187, in the 3rd movement you will hear a similarity. Perhaps this was a goof on Chopin's part, which he realized late.