setting. The Leslie speaker treatment applied to Lennon's vocal originated from his request that Martin make him sound like he was the Dalai Lama singing from the top of a high mountain. Reising describes "Tomorrow Never Knows" as the inspiration for an album that "illuminates a path dedicated to personal freedom and mind expansion". He views the song's message as a precursor to the more explicitly political statements the Beatles would make over the next two years, in "All You Need Is Love" and "Revolution". North American format "I'm Only Sleeping", "And Your Bird Can Sing" and "Doctor Robert" were the tracks omitted from Capitol's version of Revolver. In the case of "I'm Only Sleeping", the version issued on Yesterday and Today was a different mix from that included on EMI's Revolver. Due to the exclusion of the three Lennon tracks, there were only two songs on the Capitol release for which he was the principal writer, compared with three by Harrison and six by McCartney. In Riley's opinion, aside from underplaying Lennon's contribution, his voice is thereby confined to a "sudden swing to the surreal" at the end of each LP side, which distorts the intended mood across the album. The eleven-song North American LP was the band's tenth album on Capitol Records and twelfth US album in total. The release of Revolver marked the last time that Capitol issued an altered UK Beatles album for the North American market. When the Beatles re-signed with EMI in January 1967, their contract stipulated that Capitol could no longer alter the track listings of their albums. Packaging Artwork The cover for Revolver was created by German-born bassist and artist Klaus Voormann, one of the Beatles' oldest friends from their time in Hamburg during the early 1960s. Voormann's artwork was part line drawing and part collage, using photographs mostly taken over 1964–65 by Robert Freeman. In his line drawings of the four Beatles, Voormann drew inspiration from the work of the nineteenth-century illustrator Aubrey Beardsley, who was the subject of a long-running exhibition at London's Victoria and Albert Museum in 1966 and highly influential on fashion and design themes of the time. Voormann placed the various photos within the tangle of hair that connects the four faces. Turner writes that the drawings show each Beatle "in another state of consciousness", such that the older images appear to be tumbling out from them.