BLACK SABBATH released their third studio album "Master of Reality" on August 6th, 1971, through Vertigo in Europe and Warner Bros. in the United States. Recorded at Island Studios in London across two blocks of sessions in February and April with producer Rodger Bain, it is the album where Tony Iommi began detuning his guitar as far as three semitones — originally to ease the pain in the fingertips he had lost in an industrial accident — and in doing so invented the sonic vocabulary that stoner rock, sludge and doom metal would spend the next fifty years exploring. "Sweet Leaf," "Children of the Grave" and "Into the Void" are among the heaviest recordings of their era by a considerable margin. Critics of the day were dismissive; the album is now routinely named one of the foundational documents of heavy metal.
