Three years and one great album after they were booed at the 1995 Source Awards, OutKast still held a grudge against the rap establishment. On the last song of Aquemini, the scorching, Funkadelic-flavored “Chonkyfire,” they finally squashed it. As the track melts away, they hit play on the entirety of their Best New Artist acceptance speech, on which a 20-year-old André Benjamin claimed he was tired of “them closed-minded folks” and asserted that “the South got somethin’ to say.”

If the previous 71 minutes of Aquemini had proven anything, it was that Dre and Big Boi had plenty to say to closed-minded rap purists. Two years earlier, they fretted about their new fame leaving them floating face down in the mainstream, but with Aquemini, that question turned moot: They put Atlanta on the map while hovering far above the noise. Aquemini was not only the best album released in 1998, it was also Southern rap’s The Chronic and Are You Experienced?, a rap album full of live funk that established new lanes for “real”-ness and psychedelia. The same year that Jay-Z hit the pop charts, New Orleans blew up, and Lauryn Hill’s R&B/rap mind-meld swept the Grammys, OutKast earned their crown—one of their own design.

Driven by Dre’s increasingly spaced-out spirituality—a cocktail of astrology, Rastafarianism, and Baduizm—and leveled by Big’s technical skill and knack for hooks, and as always supported by the duo’s Dungeon Family associates (including members of Goodie Mob) and the Organized Noize team of producer/instrumentalists, Aquemini doubled down on ATLiens’ groove-first extra-terrestrialisms in service of their own Southern-fried G-Funk. Needless to say, the first single from the album, “Rosa Parks,” was unprecedented in popular music, let alone rap: a brilliant flip of 1960s Civil Rights iconography into a back porch country hoedown (complete with harmonica solo) themed to OutKast’s dominance. The deep-cut “Liberation,” featuring Cee-Lo Green and Erykah Badu, was equally novel for a putative rap record—a brooding, nine-minute jazz-n-b meditation on black identity and struggle that dialogued directly with Badu’s nascent Soulquarian collective.

Eight years before Idlewild, OutKast wrote a feature-length screenplay to accompany Aquemini. Though a studio squashed the film idea, the album’s “Da Art of Storytellin’” diptych clearly demonstrates that the duo’s capacity to work in Southern hood realism and post-apocalyptic sci-fi modes. Then there’s the eternally great “SpottieOttieDopaliscious” on which the full gamut of the duo’s world-weariness and knack for rich detail power seven delirious minutes of blaxploitation reggae. At a time when rap storytelling primarily comprised coming-of-age stories that inevitably ended in wild success, Dre and Big carved out new narrative territory: both new fathers in their early twenties, they warned of the inevitable comedown of street life and recalled being too drunk to get out of the van at the club. It’s not hard to imagine a precocious, preteen Kendrick Lamar taking notes.

The late 1990s were an odd time for pop music, and 1998 might have been the weirdest of all. While styles and scenes rapidly mutated into new forms, digital technologies transformed adventurous sampling and genre recombination into the pop norm, not the exception. OutKast were the new kings of this fractured landscape, and Aquemini is their magnum opus, a minor miracle of creative synthesis. Perhaps most impressively, they pushed against the tides of gangsta rap without sounding like scolds, coming across like true iconoclasts probing the outer reaches of what the culture could withstand. No one has matched it since. –Eric Harvey

Listen: OutKast, “SpottieOttieDopaliscious”