While Haydn didn't necessarily invent the string quartet, he certainly helped codify it as a form. Mozart took his lead from Haydn and contributed his genius to the quartet also. These were the two composers that loomed over Beethoven when he was composing his first set of six quartets, Opus 18. As was Beethoven's way, he seldom stayed very long in any niche with his compositions. That's not to say he had no style, but that it could be broad and encompass quite different ideas. The String Quartet No. 11 is one of his giant-step compositions that is quite different from his other string quartets in form and feeling.
Beethoven always showed his originality, even in his first quartets, but he also worked hard to have them conform somewhat to the form as devised by Haydn. He managed to straddle the two extremes of originality and conformity with his first six quartets. His next three quartets, the so-called Rasumovsky Quartets of opus 59 show his development in his craft and the gap between creative originality and tradition grew wider. His next quartet, No. 10 nicknamed 'The Harp' because the strings play pizzacato a lot in the first movement follows the trend. The 11th got its nickname from the tempo indication of the third movement, allegro assai vivace ma serioso. The overall feeling of the quartet is indeed serious, and there are some surprises along the way.
The 11th was composed in 1810 but did not have its first performance until 1814. The first movement opens with the four strings playing the first theme loudly in unison, somewhat of a surprise as to the suddenness of the beginning and the downright harshness of it. The second theme is sweeter in nature in the beginning, but there also outbursts within it. An experienced listener who is hearing this quartet for the first time would be expecting to hear the exposition repeated as the style of the times dictated, but Beethoven has no repeat signs and the music jumps right into the development and recapitulation. The first movement is very short, usually less than five minutes, which in itself is a break from the traditional long first movements. Beethoven boiled down the contents of the first movement to the essence of expression.
The second movement is in song form and leads into the third movement, a scherzo of the most 'serious' kind. The finale goes through a gentle beginning, a spirited rondo movement proper and ends up with all things, a fast, upbeat, short coda that ends the work. This rather 'happy' musics appearance in an otherwise quite serious work can be interpreted in a number of ways. Perhaps Beethoven felt the need to lighten the mood before the end of the quartet, or perhaps he was just playing with the emotions of the listener as he used to do when he improvised on the piano by playing something heavy and then something light at the end.
This quartet is like a conversation between four people, a spirited conversation to be sure, but a conversation and not an argument. What the subject matter of the conversation is in words is anybodies guess. But that conversational quality of chamber music in general and the string quartet in particular, is what's so attractive about it. This quartet with its condensed first movement, surprises that run throughout and the way it ends keeps it somewhat of an enigma. But that too makes it attractive to the ear. And when regard is given for the quartets that come after this one, the great late quartets of Beethoven, we realize that we have heard only the beginning of his genius in the form.