Pink Floyd's "The Dark Side of the Moon" was primarily inspired by the mental illness suffered by former band member Syd Barrett. Barrett was the original lead singer for the band, but drug use and a descent into erratic behavior led to his departure. Roger Waters, another member of the band, proposed an album based around the pressures and the influences that could drive someone mad.
Syd Barrett was one of the original members of Pink Floyd from its inception in 1965. He became interested in psychoactive drugs during the band's early years, and by 1967 they began to take a toll on his creative output and performance. He also began to behave erratically, failing to show up for gigs and refusing to play songs correctly. In 1968, after Barrett began dropping out of shows entirely and became difficult to work with in the studio, the band announced his departure.
One of the creative devices Roger Waters used for the album is the inclusion of random voices, especially during the intro and outro of some of the songs. Waters posed a variety of pointed psychological questions to roadies, bandmates and friends, and his favorite answers made it into the songs. For instance, the end of the song "Money" contains a quote from Wings guitarist Henry McCullough.