Doom Generation: Inside Black Sabbath's MASTER OF REALITY

Black Sabbath was only two albums into the band's storied career when they produced what many believe to be their magnum opus: Master of Reality. Still riding high on the success of 1970 release, Paranoid, Sabbath was more than ready to stretch out and really rock. With guitarist Tony Iommi tuning his guitar down a step and half to make it easier to play (and bassist Geezer Butler doing the same to match), the resulting lower than low bottom-end created an ominous sound that would lay the blueprint for everything from heavy metal to grunge.

"I believe Master Of Reality was a lot heavier than anything we'd attempted before. We had a lot more confidence and really wanted it to use this properly," drummer Bill Ward told Metal Hammer in 2016. "On the previous two records, we had so little time that all we could do was record as a live band - that was our strength, anyway. We'd done so many gigs that we were very tight. But this was the first time when we didn't have gigs booked in, and could just focus on making the album a landmark."

The landmark recording arrived with a landmark intro: the most famous cough in rock and roll history that opens first track, "Sweet Leaf."

"Yes, this was done deliberately. And totally appropriate for the song, because it is about marijuana," Ward cackled about the tune. As for the identity of the person coughing? "Tony Iommi! He'd just sucked on a big joint," Ward regaled. "We had the tapes rolling, and it was the perfect way to begin the record."

Released on July 21, 1971, Master of Reality was the first Black Sabbath album to crash the top 10 on the American charts, peaking at #8 for the week of September 25, 1971 (they'd come close with Paranoid, which hit #12). The #1 album in America that week: Carole King's Tapestry. It launched the band on an epic world tour that lasted for more than a year.

"I always look at the first three albums as being part of the same time period for us. But for me, it was Master Of Reality that defined how good we'd become," Ward said. "I know people feel that Sabbath invented heavy metal with our debut album - and that is true to some extent, but I believe that it's with Master Of Reality that we proved the potential and power of the music. It's also a record when we weren't afraid to show our vulnerable, sensitive side."