Black Sabbath are the archetypal heavy metal band, the blueprint for countless imitators that sprang up in the late Seventies. While Deep Purple had classical pretensions and Led Zeppelin indulged in mysticism, Sabbath blended down-to-earth heavy rock with highly theatrical occult imagery. Their menacing presence, aided and abetted on stage by the manic leaps of singer Ozzy Osbourne, provided an aggressive contrast to late Sixties flower power. It also established a musical formula, which would, with time, come to seem restrictive, and lead to serious disagreements within the band.
The four original members - guitarist Tony Iommi,...