One of more interesting facets of Sgt. Pepper's was the Beatle's use of abstract lyrics. In the early years of Rock lyrics were expected to make sense. But, how do you make sense out of Lucky in the Sky with Diamonds? Later, "I Am the Walrus, and Abbey Road's "Come Together" became even more abstract. I think this was one of Lennon's greater contributions to rock. (However, one has to give Bob Dylan credit for being among the first to use abstract lyrics) For Lennon, it was like throwing paint on a canvas and allowing the viewer to see what they saw. If no two people saw it the same way, the better. The lyrics of these songs create unique images in the mind and perceptions of reality. What bands today are good at employing abstract lyrics?

The Mars Volta

pretty much all of the lyrics could be described as abstract, never really have a clear idea of what he (Cedric Zavala) is talking about.

I don't have time to get into specifics now, but Andrew Bird's lyrics are always crazy and open to many interpretations.