They just don’t make them like they used to. Outside of Grimes’ or Cat Power’s onstage vulnerability, no one does unpredictable like Fiona Apple. Ever since she cackled “This world is bulls---” during an acceptance speech at the 1997 MTV Video Music Awards, the songwriter and pianist has remained an enchanting curiosity of the pop-rock scene.

Her 1996 debut album, Tidal, crashed into the mainstream at a time when Fierce Females were being trotted out by major record labels like prize-winning thoroughbreds. Bolstered by the then-recent artistic and commercial successes of Tori Amos, Hole and Sheryl Crow --  to say nothing of the stratospheric heights reached by Alanis Morrissette's Jagged Little Pill the year before -- by 1996, women were finally starting to get a fair shake on rock radio.

Apple’s label, Sony, took a hands-off approach to the offbeat jazz on Tidal, but marketed the then-19-year-old as a slinky coquette. (See the sexy video above for “Criminal,” which was accused by many to glorify heroin chic.) But Apple was mature beyond her years in tonality, command of her instrument and subject matter. While her teen contemporaries such as the Backstreet Boys were crooning about cotton-candy romances, she was contemplating adult sensuality (the seductive “Slow Like Honey”) and virginal sacrifice (“The Child Is Gone”).

The young artist had more in common with jazz’s volatile talents. She was Nina Simone reincarnated as a “Sullen Girl,” to quote another Tidal track. She was gorgeous and spellbinding, and her fragility made her even more appealing to feminist fans and critics.

This mind, this body and this voice cannot be stifled by your deviant ways,” she dismisses in opening song “Sleep to Dream.” It’s a finger-snapping sendoff to little boys and tongue-wagging men who wanted to own and control her—but in its confidence, it also conveys weariness. “I got my feet on the ground, but I don’t go to sleep to dream,” Apple sings in the chorus. Despite finding some catharsis in songwriting, she always seemed to be outrunning inner demons. She’d further explore that concept on 2012’s The Idler Wheel Is Wiser Than the Driver of the Screw and Whipping Cords Will Serve You More Than Ropes Will Ever Do, but Tidal was the cradle for her illustrious madness.

Beyond being body-shamed for her thinness and being put in a figurative straitjacket by naysayers, Apple could sing. Over a swelling string arrangement by the legendary Van Dyke Parks on “Never Is a Promise,” she undulated between an awesome contralto and a heartbreaking falsetto. Her first single, “Shadowboxer,” was breathy and pugnacious. And the seesawing force of “Carrion” closed the album with a memorable flash of her fangs. In it, she eviscerated a former lover and insisted, “You can’t intimidate me back into your arms.” It was an anthem of walking away on one’s own terms, without fear of physical or emotional retaliation.

Tidal swept up Grammys, MTV Video Music Awards and best-of-the-year nods, but its most vital legacy is that it made it OK for ugly feelings to manifest into beautiful songs. Apple became one of Generation X’s preeminent poets of the piano, a “bad, bad girl” like Angelina Jolie, all pout and pith. She likely introduced many alternative rock fans to jazz, bebop and the blues with her Ella Fitzgerald inflections and her torchy delivery. And as we now know, Tidal was just a glimpse into the Extraordinary Machine-ry of Apple’s mind.

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