Now a proven commercial commodity, even if rock’s critical aristocracy chose not to acknowledge it, Black Sabbath had earned the benefit of a much larger budget and more time to make their third album, 1971's ‘Master of Reality,’ which the band gradually pieced together as they juggled increasing touring commitments.

Even though it lacks 'Paranoid''s incredible harvest of career-defining classic songs, ‘Master of Reality’ delivers another batch of power-chord monoliths like ‘Sweet Leaf’ (the official birth of stoner rock), ‘Children of the Grave’ (another antiwar anthem for the ages) and ‘Into the Void’ (doom blasted into outer space) that remain at the top of every Sabbath fan's best-of list.

‘Master of Reality’ takes on a heavier and gloomier tone than any of the records that preceded it. It's no accident. Guitarist Tony Iommi and bassist Geezer Butler de-tuned their strings super-low (three semi-tones below the standard E tuning, in case you care about such things) to produce the album’s ominous, sludgy sound.

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