The third movement, Allegro moderato is a mere fragment, an operatic-like recitative in A major that introduces the fourth movement, an extended set of seven variations that sticks very tightly to A major, while unfolding an impressive array of rhythmic and textural variety. Let's listen to the third and fourth movements:
The fifth movement, a Presto scherzo and trio, is based on a simple, rustic theme. In his later works, Beethoven is capable of some remarkably child-like music. One of my favorite passages occurs towards the end when a really remarkable effect is used: the strings are asked to play sul ponticello which means that the bow is played close to the bridge, giving an eerie, nasal sound (about 5:18 in the clip). Then they move back to a normal position. I think this might have been the first use of this technique--and what is remarkable is that Beethoven was completely deaf when he wrote this so he had to rely on his mind's ear alone. Here is the Presto:
The sixth movement, like the third, is a mere fragment, a cavatina-like lament. This movement was chosen as the soundtrack for a poignant moment in the TV series Band of Brothers. I find delightful the character's comment "That's not Mozart -- that's Beethoven." He says "Beethoven" with exactly the right inflection.
They repeat the movement for the purposes of the soundtrack and overlay it with dialogue, so let's hear it straight and followed, without pause, by the last movement. Let me point out again, how powerfully this quartet hangs on four notes: C# D A G#. These were the stressed notes (and their resolutions) in the very beginning of the fugue and the whole quartet has been a kind of writing large of them. The first movement was in C# (minor), the second in D, the third and fourth in A, the fifth in E (the only real departure) and now the sixth in G# (minor) followed by the finale in C# minor. For the last movement, which the whole quartet has been leading up to, Beethoven unleashes all his resources as a composer. You can hear echoes of the previous movements, but no exact repetitions of themes. There are great soaring mottos, like a kind of cantus firmus over top of the wild dance.
One Karl Holz reports that Beethoven said to him regarding this movement the most astoundingly humble thing: "An Phantasie fehlts, Gottlob, weniger als je zuvor" which we could translate as "thank God, there is less lack of fancy than ever before..."