Beethoven's Piano Sonata in G major, op. 49, no. 1, first movement played by Claudio Arrau. There are great comments on this video that help with expression of the piece, ex: "The very first few notes must be Clear and Determined", "Executing all those slurs at tempo in the 2nd mvt, a great contrast to the 1st, alone should make this harder than even Op 2/1, which I have played. As the marking is 'Andante' and each harmony usually takes up one measure ideally the tempo should be around 20% faster, but this is still OK"