Peter Wollny has known the Ciacona in D minor and the Ciacona in G minor for more than 30 years now — ever since he discovered the organ works at the Royal Library of Belgium. The handwritten manuscripts were from an unknown writer — undated and unsigned. Yet Peter Wollny, now director of the Bach Archive in Leipzig  , had a sense his discovery could actually be a hidden treasure, composed by Johann Sebastian Bach . His meticulous hunt for clues began. "To confirm the pieces' identity, I