We can argue all day long about who invented heavy metal. But there’s no denying that Black Sabbath largely shaped the genre. Tony Iommi, Bill Ward, Geezer Butler and Ozzy Osbourne banded together to form the legendary quartet in 1968. Four months after releasing their self-titled debut album, the Birmingham, England boys were back in the studio for a follow-up record. Originally written as an afterthought, “Paranoid” became both the title track and the band’s signature song. And 54 years ago today, on Aug. 7, 1970, the world heard it for the first time.