Between 1970 and 1972, Black Sabbath released four albums that still stand as one of the greatest hot streaks in rock – Black Sabbath, Paranoid, Master Of Reality and Vol. 4. But when it came to making their fifth album, they found the tank was empty.
"I got writer’s block," said Tony Iommi. "It just went dead. We had the studio booked. And it was just one of those times. I really panicked: ‘Oh my God, I can’t seem to think of anything that we like!’. I could play stuff, but it just wasn’t sinking in; I didn’t like it."