As far as endings go, The Big Lebowski's is probably one of the more satisfying. The Dude solves the mystery, defeats the Big Lebowski, and gets rid of those pesky German nihilists. Everything could be tied up with a neat little bow if it weren't for Donny's tragic passing. Rest in peace, Donny. 

And, of course, the Dude can return to his favorite place: the bowling alley.

In the final scene, The Dude has his last conversation with the cowboy narrator. This is where The Dude utters the classic line: "The Dude abides." It's a reference to Ecclesiastes 1:4 in the Bible: "One generation passes away, and another generation comes: but the earth abides forever." Translation? Things may change and get crazy around him, but The Dude is still The Dude. 

Now, the movie takes on a super cosmic-psychedelic view of the universe: The Dude's predicament is one in a sea of predicaments, we are all grains of sand on the mighty beach that is the cosmos. 

Everything is nothing and nothing is everything, man.

While we're on the subject, it's worth mentioning that Walter's Judaism (and the Coens') may be reflected in the cowboy. Some people—like the author of this article—have posited that the Stranger is actually a religious figure of some kind: either God—atching and narrating as he does—or Elijah, the Jewish mythic figure who wanders the earth and declines to show up every Passover.