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1971–1973: Master of Reality and Vol. 4

In February 1971, after a one-off performance at the Myponga Pop Festival in Australia, Black Sabbath returned to the studio to begin work on their third album. Following the chart success of Paranoid, the band were afforded more studio time, along with a "briefcase full of cash" to buy drugs. "We were getting into coke, big time", Ward explained. "Uppers, downers, Quaaludes, whatever you like. It got to the stage where you come up with ideas and forget them, because you were just so out of it."

Production completed in April 1971, and in July the band released Master of Reality, just six months after the U.S. release of Paranoid. The album reached the top 10 in the U.S. and the United Kingdom, and was certified Gold in less than two months, eventually receiving Platinum certification in the 1980s and Double Platinum in the early 21st century. It contained Sabbath's first acoustic songs, alongside fan favourites such as " Children of the Grave " and " Sweet Leaf ". Critical response of the era was generally unfavourable, with Lester Bangs delivering an ambivalent review of Master of Reality in Rolling Stone, describing the closing "Children of the Grave" as "naïve, simplistic, repetitive, absolute doggerel – but in the tradition... The only criterion is excitement, and Black Sabbath's got it". (In 2003, Rolling Stone would place the album at number 300 on their 500 Greatest Albums of All Time list.)

Following the Master of Reality world tour in 1972, the band took their first break in three years. As Ward explained: "The band started to become very fatigued and very tired. We'd been on the road non-stop, year in and year out, constantly touring and recording. I think Master of Reality was kind of like the end of an era, the first three albums, and we decided to take our time with the next album."

In June 1972, the band reconvened in Los Angeles to begin work on their next album at the Record Plant. With more time in the studio, the album saw the band experimenting with new textures, such as strings, piano, orchestration and multi-part songs. Recording was plagued with problems, many as a result of substance abuse issues. Struggling to record the song "Cornucopia" after "sitting in the middle of the room, just doing drugs", Ward was nearly fired. "I hated the song, there were some patterns that were just... horrible," the drummer said. "I nailed it in the end, but the reaction I got was the cold shoulder from everybody. It was like, 'Well, just go home; you're not being of any use right now.' I felt like I'd blown it, I was about to get fired". Butler thought that the end product "was very badly produced, as far as I was concerned. Our then-manager insisted on producing it, so he could claim production costs".

The album was originally titled Snowblind after the song of the same name, which deals with cocaine abuse. The record company changed the title at the last minute to Black Sabbath Vol. 4. Ward observed, "There was no Volume 1, 2 or 3, so it's a pretty stupid title, really". Vol. 4 was released in September 1972, and while critics were dismissive, it achieved Gold status in less than a month, and was the band's fourth consecutive release to sell a million in the U.S. "Tomorrow's Dream" was released as a single – the band's first since "Paranoid" – but failed to chart.

Following an extensive tour of the U.S., in 1973 the band travelled again to Australia, followed by a tour for the first time to New Zealand, before moving onto mainland Europe. "The band were definitely in their heyday", recalled Ward, "in the sense that nobody had burnt out quite yet".