After a pause of four years, Beethoven returned to the piano sonatas genre in 1809. Unlike its predecessor, the F minor Sonata op. 57 (the “Appassionata”), this work strikes a new and lyrically cantabile tone that must have been the reason for its tradition-breaking two-movement structure; a slow middle movement would not have provided the necessary contrast to the outer ones. Just as unusual as the key of opus 78 is its four-measure Adagio introduction; this does not directly refer to the subsequent motifs and themes, and serves no other purpose than to “conjure up the atmosphere of the entire sonata in our hearts”.