Beethoven's "Eroica" SketchbookBeethoven's many surviving sketchbooks bear witness to the vast creative labor that lay behind the musical masterpieces he left to posterity. Among them, one of the most famous is the ""Eroica"" Sketchbook, containing all the known sketches for the ""Eroica"" Symphony, the ""Waldstein"" Sonata, and other works of 180304. These include his first sketches for the opera Leonore (later entitled Fidelio), as well as the unfinished opera Vestas Feuer, the