In 1912 Heinrich Schenker contracted with the publisher Universal Edition to provide an 'elucidatory edition' (Erläuterungsausgabe) of Beethoven's last five piano sonatas. But that of the 'Hammerklavier' Sonata, op. 106, was never published. As Nicholas Marston shows in a detailed history of the Erläuterungsausgabe, despite Schenker’s failure to