In 1966 John Lennon's philosophical journey began that led to the genre shattering "Tomorrow Never Knows"!
The song was released in 1966 and the final track on "Revolver," and marked a turning point for the Beatles, as The Beatles embraced the studio creating music not necessarily made for reproducing in concert.
Coming from Lennon's experiences with LSD and his reading of the 1964 book The Psychedelic Experience: A Manual Based on the Tibetan Book of the Dead by Timothy Leary, Richard Alpert and Ralph Metzner. The Beatles' recording went away from pop music and featured an Indian-inspired modal backing of tambura and sitar drone. Along with tape loops prepared by the band that were overdubbed, Lennon's voice was fed through a Leslie speaker cabinet, as the song's backwards guitar parts and effects marked the first use of reversed sounds in a pop single.
"Tomorrow Never Knows" was the signature song to announce the psychedelic movement that would rule the second half of the 60s, and pioneer sampling, tape manipulation and other production techniques still used today. It's lyrical themes explored mind expansion, anti-materialism and Eastern spirituality into pop music, and was a pinpoint moment of the next evolution in music.