When the world first discovered Norwegian black metal, it was largely thanks to a well-publicized crime spree that left several scenesters dead or in jail.

Most of the music available at that point -- by bands like Mayhem, Darkthrone, and Burzum -- was intentionally ugly, poorly produced, and proud of it.

It might have been easy for outside observers to dismiss the music itself as inconsequential noise; that is, if Emperor's debut album In the Nightside Eclipse hadn't arrived at exactly the right moment.

Released just a few months before the well-publicized murder trial of Varg Vikernes, the album would itself soon find three of its four performers imprisoned.

But for anyone drawn in by the surrounding sensationalism, In the Nightside Eclipse resoundingly demonstrated that there was real musical substance and ambition in the world of black metal.

Its epic vision didn't mesh with the general "anti-music" mind set of the rest of the scene, yet somehow managed to capture the essence of the genre while completely rewriting its rule book.

All the basic black metal trademarks -- furious blastbeats, tremolo-picked chords, raspy reptilian vocals -- are here, but combined with atmospheric keyboards, symphonic grandeur, and poetic (if indecipherable) lyrics about nature and ancient Scandinavian paganism.

(Well, OK, and Satan too.) This is music that's extreme yet expressive, meant to evoke not just darkness and death, but the chill of a Norwegian winter, the dread underpinning traditional folktales, and the harsh and unforgiving landscape depicted on the front cover.

Even if the keyboards mostly just outline basic chord changes, they add a melancholy air to all the furious extreme sounds, turning the one-note ugliness of black metal into something emotionally complex.

Original bassist Mortiis had already moved on to a solo project, but his pagan poetry and interest in dark ambient music have left their mark; his earliest co-writes here, "I Am the Black Wizards" and "Cosmic Keys to My Creations and Times," are among the most striking tracks on the album, even if his input was only lyrical.

It's true that the raw, lo-fi production -- in keeping with the standard black metal aesthetic of the time -- obscures some of the music's detail, rendering it an impenetrably thick wall of noise.

For many fans, this actually enhances the much-vaunted ambience of the album, since it's hard to pick out individual elements, everything washes together into a monolithic whole.

It does take a few listens for even the most memorable riffs and melodies to emerge from the maelstrom, and of course, that outward inaccessibility is exactly what black metal purists demand.

Nevertheless, it was pretty clear that Emperor's ambition wouldn't stand for not letting their listeners hear everything they were doing, setting the stage for a major production leap on their next album.

In the meantime, though, In the Nightside Eclipse took its place as perhaps the definitive black metal album.

It pointed the way toward greater use of atmosphere and melody; it was the first to fuse black metal with progressive and symphonic elements, setting the stage for a bevy of future experimentation in the genre, and it created a template for using folk traditions and melodies from one's homeland as inspirations for material.

As such, it certainly possesses the farthest-reaching legacy of anything from Norway's bloody first wave, and ranks as one of the most important heavy metal albums of the ‘90s.