Einstein on the Beach was completed in 1976, and quickly became notorious in the musical circles. It was an "opera" composed by Philip Glass and designed by Robert Wilson, which was less of an opera than a show of the vivid collective imaginations of its creators. A snipit of text from the liner notes of the 1993 recording (performed by the Philip Glass Ensemble and conducted by Michael Reisman):

Einstein broke all the rules of opera. It was four interconnected acts and five hours long, with no intermissions (the audience was invited to wander in and out at liberty during performances). The acts were intersticed by what Glass and Wilson called "knee plays" -- brief interludes that also provided time for scenery changes. The text consisted of numbers, solfege syllables, and some cryptic poems by Christopher Knowles (. . .) with whom Wilson had worked as an instructor of disturbed children (. . .) Einstein sometimes seemed a study in sensory overload, meaning everything and nothing.
- Tim Page

An exerpt from one of the "knee plays":

Prematurely Air-Conditioned Supermarket
written by Lucinda Childs

I was in a prematurely air-conditioned super market
and there were all these aisles
and there were all these bathing caps that you could buy
which had these kind of Fourth of July plumes on them
they were red and yellow and blue
I wasn't tempted to buy one
but I was reminded of the fact that I had been avoiding
the beach.