"Tomorrow Never Knows" was the most experimental and psychedelic track on Revolver, in both its structure and production. This was not a song that could be easily sung by a rock group live, as the special effects and tape manipulation that were integral to the tune could not be re-created on-stage. In addition, there was a conspicuous absence of the riffs and verse-bridge-chorus-dominated construction that had colored virtually every original Beatles composition before 1966. The underpinnings of "Tomorrow Never Knows" were a single-tone drone, influenced by the group's growing interest in Indian music, and unforgettable stop-start, stuttering drum patterns by Ringo Starr. Eerie high-pitched seagull-like chanting was in the background throughout; principal composer John Lennon had actually envisioned the sound of monks chanting, and if this effect was not precisely what he had in mind, it was equally memorable. The lyrics were psychedelic, which is not just a critic's assumption: some of the words were adapted from Timothy Leary's book The Psychedelic Experience and the Tibetan Book of the Dead. Regardless of the source, the lyrics were philosophical, existential, sometimes inscrutable reflections on the state of being: a heavy subject for popular music, whether in 1966 or any other year. It would be difficult to assign an interpretation to the Beatles' own viewpoint as seen through "Tomorrow Never Knows," since the words are themselves a kaleidoscopic shift of thoughts and feelings, sometimes seeming to advocate passive relaxation and acceptance, at others intense karmic exploration, and at others advising unconventional intuition (as in the exhortation to listen to the color of one's dreams). There's way too much going on in the production of the track to detail in one paragraph: readers are advised to consult Mark Lewisohn's The Beatles Recording Sessions for full details of the tape loops, organ, honky tonk piano, wine glass, and Leslie speakers employed to conjure the dreamlike ambience. Bits worth noting, however, are the final verse, in which Lennon's voice suddenly takes on an interstellar intercom-like quality; the alarm-like noise heard just as Lennon starts that final verse; the berserk gyrations of the riffs, as such, in the instrumental break, which sound like a tape being threaded through the machine on varispeed; and Lennon's insistent repetitions of "of the beginning" at the end, which puts things on a somewhat more tranquil note before everything winds down in a cacophony of chants and piano. One would think that "Tomorrow Never Knows" is one of the most uncoverable of all Beatles songs, but actually the new wave raga-rock group Monsoon (with singer Sheila Chandra) did a credible version in the early '80s.