The musicians were now starting to fully endeavour to write original material and found ideas for seven songs, more than on either of their first two albums. Musical and lyrical inspiration came from very disparate sources. The opener "Chasing Shadows" was based upon African rhythms created by drummer Ian Paice. The dour and baroque "Blind" was written by Lord about one of his nightmares. The short instrumental "Fault Line" was inspired by an earthquake that the band had experienced while in Los Angeles and featured Paice's drum patterns reversed and double tracked. Roman Polanski's movie "Rosemary's Baby", which the band members had watched together at a cinema, was the main inspiration for the blues rocker "Why Didn't Rosemary?" "April" was a tune written by guitarist Ritchie Blackmore about his birthday month before the recording sessions had begun; it was later augmented with a long middle section of classical music written by Lord, becoming the album's 12-minute-plus final track and Deep Purple's longest ever studio recording. The only cover song on the album is the Donovan-penned ballad "Lalena", which had been a Top 40 single for its author in the US in the autumn of 1968.