Thanks to a potent mix of rhythmic precision and blinding-fast tempi—just listen to the lift-off 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.