What song does Ozzy refer to in his song "Dreamer"  that was written by John Lennon, that encourages a world at peace?
Imagine (John Lennon song) "Imagine" is a song written and performed by English musician John Lennon. The best-selling single of his solo career, its lyrics encourage the listener to imagine a world at peace without the barriers of borders or the divisions of religion and nationality, and to consider the possibility that the whole of humanity would live unattached to material possessions.
All Things Must Pass (song) "All Things Must Pass" is a song by English musician George Harrison, issued in November 1970 as the title track to his triple album of the same name. Billy Preston released the song originally – as "All Things (Must) Pass" – on his Apple Records album "Encouraging Words" (1970), after the Beatles had rejected it for inclusion on their "Let It Be" album in January 1969. The composition reflects the influence of the Band's sound and communal music-making on Harrison, after he had spent time with the group in Woodstock, New York, in late 1968, while Timothy Leary's poem "All Things Pass", a psychedelic adaptation of the Tao Te Ching, provided inspiration for his song lyrics.