Hack originally wrote this book in 1960 under the title “Horny Angels Come to Earth to Screw Horny Men,” but reworked it after his cover artist Jonny M. told him of his fondness of Ms. McLachlan’s music and especially her song “Angel.” Although Jonny created the cover for the rewrite because he was contractually obligated to, the pornographic nature of the novel drove a rift between the two men that took years to heal.