“The best reason to hate Bach’s Goldberg Variations,” writes pianist Jeremy Denk, “is that everybody loves them.” As part of Denk’s iconoclastic challenge to this universal love, he cites another reason: “everyone asks you all the time which of the two Glenn Gould recordings you prefer.” Without a doubt the most celebrated pianist of the twentieth century, and perhaps the greatest interpreter of Bach’s keyboard compositions, the eccentric genius Gould famously opened and closed his career with the Goldberg Variations, Bach’s “annoyingly unimpeachable” (in Denk’s words) Baroque piece, written originally for the harpsichord. Gould made his first recording of the piece in 1955, and it immediately launched him to stardom, becoming “what may well be the best known of all piano recordings,” Colin Fleming tells us, with its “masterful showing of command, balance, [and] vigor.”

Twenty-six years later, Gould made his second recording, in 1981, a year before his untimely death at the age of 50. Gould had already retired from public performance 18 years earlier, due in part to his stage fright, but also to a devotion to studio recording techniques that allowed him total control over his musical output. The filmed recording session of Gould’s second Variations, above, opens with a shot not of the pianist and his instrument, but of the bank of analogue dials and switches inside the studio’s control booth. As the camera pans over and pushes in to Gould himself at the piano, we hear the familiar melody of the Goldberg aria, slowed to a snail’s pace. Gould sits in his familiar hunched-over posture, looking aged beyond his years, his body swaying over the keys in an expressive genuflection to the piece that made him more famous—and more controversial—than perhaps any other classical musician.

The shift in Gould’s style between the two Goldberg recordings is remarkable. Revisiting Gould’s legacy thirty years after his death, pianist Steven Osbourne writes in The Guardian of the 1981 performance above:

The contrapuntal detail he finds in every bar is amazing; no one has equalled the way he plays the aria. But even more extraordinary is the line he creates that connects the whole piece. I’m not sure I have heard anything where every single note is placed so carefully, is so carefully thought about. For some people, it’s too controlled, but I don’t find that.

“And yet,” says Osbourne, “I prefer his 1955 recording of the piece. I can’t think of a single artist who made such a profound change in their approach to a piece throughout their whole career.” Certainly Gould’s first Goldberg recording—fueled, as the liner notes inform us, by five bottles of pills, “all different colors and prescriptions”—stands as perhaps the most idiosyncratic, and memorable, rendering of Bach’s composition. But while the first performance has “speed and lightness going for it,” writes Erik Tarloff in Slate, the second has “an autumnal grace and the marvelous clarity Gould seems to privilege above all other qualities.” Luckily for us, Gould, who “never recorded the same piece twice,” but for this “significant exception,” left us these two career bookends to debate, and enjoy, endlessly.

The Art of Fugue: Gould Plays Bach