Master Of Reality And Volume 4 (1971–1973)

In February 1971, 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, bigtime", 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 release of Paranoid. The album reached the top ten in both the US and UK, and was certified gold in less than two months, eventually receiving platinum certification in the 1980 and Double Platinum in the early 21^st century. Master of Reality contained Black Sabbath's first acoustic songs, alongside fan favourites such as "Children of the Grave" and "Sweet Leaf". Critical response of the era was again unfavourable, with Lester Bangs of Rolling Stone dismissing Master of Reality as "naïve, simplistic, repetitive, absolute doggerel", although the very same magazine would later place the album at number 298 on their 500 Greatest Albums of All Time list, compiled in 2003.

Following the Master of Reality world tour in 1972, Black Sabbath took its first break in three years. As Bill 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. The recording process was plagued with problems, many as a result of substance abuse issues. While struggling to record the song "Cornucopia" after "sitting in the middle of the room, just doing drugs", Bill Ward was nearly fired from the band. "I hated the song, there were some patterns that were just... horrible" Ward 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". 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, with Ward stating "There was no Volume 1, 2 or 3, so it's a pretty stupid title really".

Black Sabbath's Volume 4 was released in September 1972, and while critics of the era were again dismissive of the album, it achieved gold status in less than a month, and was the band's fourth consecutive release to sell a million copies in the US. With more time in the studio, Volume 4 saw the band starting to experiment with new textures, such as strings, piano, orchestration and multi-part songs. The song "Tomorrow's Dream" was released as a single—the band's first since Paranoid—but failed to chart. Following an extensive tour of the US, the band travelled to Australia for the first time in 1973, and later mainland Europe.