In a Songfacts interview with Tony Iommi
, he talked about writing this song. "I had a wah-wah going and started playing this riff, which was 'Supernaut,'" he said. "Everybody liked it, and we made it into the song."
"That's how we always went about the Sabbath stuff," he added. "I always played something and the others would have to go, 'Oh, I like that.' If nobody said anything about it, we'd just carry on and do something else. It always had to be somebody going, 'Oh, I really like that,' because I can keep playing riffs."