Strangely enough, for all of the fixation of the movie and its audience on dancing, the Bee Gees' new songs were weighted equally toward ethereal ballads, which may be one reason for the soundtrack album's appeal - it delivers what its audience expects, plus a "bonus" in the form of the soaring, lyrical romantic numbers that were, as with most ventures by the Gibb Brothers in this area, virtually irresistible. Instead, Stigwood fired him and brought in the very talented but much more agreeable John Badham, the movie's title was changed to Saturday Night Fever, the Bee Gees' music stayed, and the result was the biggest-selling soundtrack album in history, a 25-million copy monster whose sales, even as a more expensive double-LP, dwarfed the multi-million units sold of Children of the World and Main Course. The group's involvement even survived the decision by the original director, John Avildsen, that he didn't want their music in the film. More out of loyalty to him than any belief in the viability of the film, they obliged. Instead, Robert Stigwood asked them in early 1977 to contribute songs to the soundtrack of a movie that he was financing, a low-budget picture called Tribal Rites on a Saturday Night. The Bee Gees had written "Stayin' Alive" (then called "Saturday Night"), "Night Fever," "How Deep Is Your Love," "If I Can't Have You," and "More Than a Woman" for what would have been the follow-up album to Children of the World, and they might well have enjoyed platinum-record status with that proposed album. Saturday Night Fever, as a movie and an album, plus a brace of hit singles off of it, suddenly made disco explode into mainstream, working- and middle-class America with a new immediacy and urgency, increasing its audience ten-fold overnight. Ironically, before its release, the disco boom had seemingly run its course, primarily in Europe, and was confined mostly to black culture and the gay underground in America. Saturday Night Fever, although hardly as prodigious an artistic achievement as those precursors, was precisely that kind of musical phenomenon for the second half of the '70s. Pepper's Lonely Hearts Club Band album served this purpose for the era of psychedelic music in the 1960s. Every so often, a piece of music comes along that defines a moment in popular culture history: Johann Strauss' operetta Die Fledermaus did this in Vienna in the 1870s Jerome Kern's Show Boat did it for Broadway musicals of the 1920s, and the Beatles' Sgt.