The "underground oratorios" Absolutely Free and The M.O.I. American Pageant by the Mothers of Invention are among the major achievements of experimental pop groups. The Mothers draw on a large number of sources for their music. They are competent rock musicians, as the building Invocation and Ritual Dance of the Young Pumpkin demonstrates. However, it is their humor, their satirical gift, that makes the Mothers' two oratorios notable. America Drinks and Goes Home, a selection from The M.O.I. American Pageant, for example, is a marvelous parody of closing time at a less than classy night club ("Oh, Bill Bailey? Oh, we'll get to that tomorrow night. Yeah. Caravan with the drum solo? Right. Yeah, we'll do that.").

The nice thing about the Mothers' humor on the two oratorios is that it is open and democratic rather than aimed at any specific inside group. (p...