Rodriguez describes Lennon's "Tomorrow Never Knows" as "the greatest leap into the future" of the Beatles' recording career up to this point. The recording includes reverse guitar, processed vocals, and looped tape effects, accompanying a strongly syncopated, repetitive drum-beat. Lennon adapted the lyrics from Timothy Leary's book "The Psychedelic Experience: A Manual Based on The Tibetan Book of the Dead", which equates the realisations brought about through LSD with the spiritually enlightened state achieved through meditation. Originally known as "Mark I", and then briefly "The Void", and his choice of a black-and-white cover was in deliberate defiance of the preference for vivid colour. When he submitted his work to the Beatles, Epstein wept, overjoyed that Voormann had managed to capture the experimental tone of the Beatles' new music. Voormann also designed a series of four images, titled "Wood Face", "Wool Face", "Triangle Face" and "Sun Face", which appeared on the front of the Northern Songs sheet music for each of the album's songs.