Revolver (Beatles album) group collective since 1962, and gave them an unprecedented amount of time to prepare for a new album. Writing in "The Beatles Forever", Nicholas Schaffner cites 1966 as the start of the band's "'psychedelic' period" and adds: "That adjective implies not only the influence of certain mind-altering chemicals, but also the freewheeling spectrum of wide-ranging colors that their new music seemed to evoke." Music journalist Carol Clerk describes "Revolver" as having been "decisively informed by acid", following John Lennon and George Harrison's continued experimentation with the drug LSD since the spring of 1965.<ref name="Clerk/Uncut"> Available at Rock's Backpages (subscription required).</ref>
Rarities (Beatles compilations) as part of "The Beatles Collection" box set. Most of the tracks on the "Beatles Collection" disc titled "Rarities" were already available on American Beatles LPs. As a result, Capitol assembled an album of Beatles tracks that were considered rare in America. They include tracks not previously issued on a Capitol or Apple LP and alternative versions of several well-known songs which were also not readily available in America. A highlight of the album was the gatefold sleeve featuring a reproduction of the original controversial "butcher" cover photo of the 1966 "Yesterday and Today" album. Although the Capitol "Rarities" album