Wagner studied the Opus 131 Quartet all his life, “the dance of the whole world itself,” as he called it in his 1870 essay. In its seven movements, played without pause, this pathbreaking, mood-shifting and mystical quartet could be seen as offering him a manual on how to organize a long through-composed opera to make it come across as a musical and dramatic entity.
There was a movie made last year which revolved around this quartet: "A Late Quartet." It was disappointing--too much talking and not enough quartet.