Very possibly Beethoven’s greatest sonata (it may or may not be edged out by the Hammerklavier, and also has a good punt at the title), and certainly one of the greatest piano works ever written. There is a lot to say about this, but suffice to say that Chopin admired it enough to imitate both the beginning and end of the first movement (in the opening of his B-flat Minor sonata, and in the end of the Revolutionary etude respectively).
The boogie-woogie variation is at 16:47, but the best moment of the generally awesome second movement comes at 21:56. [Brendel’s comment: “...perhaps nowhere else in piano literature does mystical experience feel so immediately close at hand.“]
This is also a marvellous rendition by Pogorelich, who plays with absolutely clarity, with no indulgence and quite a lot of intensity (as in “focus“, not “aggressive“). The tempo choice is especially good -- the music has space to breathe.
Movement I: 00:00
Movement II: 9:54 (Theme and Variations)