In 1912 Heinrich Schenker contracted with the Viennese publisher Universal Edition to provide an 'elucidatory edition' (Erl uterungsausgabe) of Beethoven's last five piano sonatas. Each publication would comprise a score, newly edited by Schenker and using the composer's autograph manuscript as principal source, together with a substantial commentary combining analytical, text-critical and performance-related matter. Four of the five editions appeared...