With 1973's Sabbath Bloody Sabbath, heavy metal godfathers Black Sabbath made a concerted effort to prove their remaining critics wrong by raising their creative stakes and dispensing unprecedented attention to the album's production standards, arrangements, and even the cover artwork. As a result, bold new efforts like the timeless title track, ""A National Acrobat,"" and ""Killing Yourself to Live"" positively glistened with a newfound level of finesse and maturity, while remaining largely faithful, aesthetically speaking, to the band's signature compositional style. In fact, their sheer songwriting excellence may even have helped to ease the transition for suspicious older fans left yearning for the rough-hewn, brute strength that had made recent triumphs like Master of Reality and Vol. 4 (really, all their previous albums) such undeniable forces of nature. But thanks to Sabbath Bloody Sabbath's nearly flawless execution, even a more adventurous experiment like the string-laden ""Spiral Architect,"" with its tasteful background orchestration, managed to sound surprisingly natural, and in the dreamy instrumental ""Fluff,"" Tony Iommi scored his first truly memorable solo piece.