Known as the Godfather of heavy metal, Black Sabbath guitarist Tony Iommi changed the way the guitar could sound. After a factory accident cost him the tips of two fingers, he was told he would never play again. Instead, he built his own prosthetic fingertips, adapted his guitar and developed a darker, heavier sound that would define a new genre. In this episode of Ways to Change the World, Krishnan Guru-Murthy talks to Tony Iommi about growing up in industrial Birmingham, forming Black Sabbath with Ozzy Osbourne, the riffs that changed rock music and the friendship that endured through decades of break-ups and reunions. As he releases his latest album From The Dark, he also reflects on Black Sabbath’s emotional final performance with Ozzy, his friend’s death shortly afterwards, and why he’s still making music.