I don't remember ever having heard Chopin's variations on "La ci darem la mano" from Mozart's Don Giovanni, Op. 2, until I heard a snippet of it on The Schumanns--Their Lives and Music, the latest Teaching Company course I'm "taking." Apparently, after hearing this piece, Robert Schumann reviewed it, writing, "Hats off, gentlemen. A genius!"
And Chopin wasn't even famous yet.
These are delightful. I'm glad I have now "discovered" them for myself. Better late than never. Hear snippets for yourself (Tracks 7 through 13) here.