Thanks to a potent mix of rhythmic precision and blinding-fast tempi—just listen to the liftoff of Variation 5—Glenn Gould burst onto the record industry's radar with his 1955 performance of this Bach masterwork. Appropriately, the pianist also closed his studio career with a more ruminative (yet still exciting) version, in 1981. Gould’s distinct intelligence, palpable in both takes, has inspired generations of Bach interpreters. And though you’ll likely have a preference among them (as well as your own opinions about Gould’s murmurings from the piano bench), you simply can’t have one performance and not the other.