According to many pop-musicologists the flat-seventh chord, or subtonic, can be regarded as one of the marks of the Beatles’ experimental period. Some of them even view the way in which the group handled this chord in their songs as one of their real musical innovations. On the Beatles’ 1966 album Revolver, this chord is paired to a lavish use of quartal harmonies. Is this peculiar chord, along with the quartal harmonies, responsible for the album’s meditative atmosphere? Answering this question, Ger Tillekens here takes a closer look at the flat-seventh in songs like “Taxman,” “I’m Only Sleeping,” “Love You To” and “Here, There, and Everywhere.”