Nirvana's impact on pop culture was intense and confounding. To this day, those involved still sift through the material remains of the sardonic, sad and incontrovertibly talented songwriter Kurt Cobain seeking clues to the life that he abandoned in 1994. Cobain was known to be a perfectionist who labored over his deceptively simple material for years, refining and rewriting songs until they were deigned ready for public consumption, but the four-disc box set With the Lights Out pulls back the curtain and reveals a more complex, less polished Nirvana. On the heels of the publication of the late singer's personal journals, this collection allows critics and fans to pore over his and the band's inchoate ideas, ranging from its first-ever performance to the final months of Nirvana's existence.

It's interesting to note that the box set begins and ends with cover songs. But the choice of tunes cleverly highlights the strange juxtapositions within Nirvana's unique merging of hard rock, experimental noise and bubblegum pop. Disc one starts the 81-track set with a relatively straightforward version of Led Zeppelin's "Heartbreaker," recorded at the band's live debut at a party in 1987. The fourth disc, a DVD of live footage, concludes with a subdued and reverent reading of the Jacques Brel lite-pop hit "Seasons in the Sun."

The set runs chronologically through the band's history, collecting B-sides, demo versions of its biggest hits, and many songs that have previously been unreleased (although several tracks have been repeatedly bootlegged and renamed on file-sharing sites over the past decade). The cassette practice-tape recording of "Smells Like Teen Spirit," for example (which sounds like it was chewed up in Kurt's old boombox), sounds so energetic and powerful, it completely revivifies the intense impact that song had when the original single was released. Elsewhere, songs featuring the group's early succession of drummers (including Melvins skinsman-on-loan Dale Crover) show the band rummaging through its range of influences as it balanced the urge to remain true to punk esotericism while gradually allowing Cobain's love of pure pop to surface.

Acoustic tracks like "Opinion" and "Old Age" rank among Cobain's finest work, while outtakes like three Leadbelly covers and "The Other Improv" show Nirvana's playful side. The DVD begins with nine songs from a downright pathetic party in 1988, where the band performs songs that would show up on the band's Sub Pop debut, Bleach, the next year. Nearly 20 other video clips follow the band's rapid ascent to the top of the pop heap.

The set, on the whole, is a must-have for Nirvana fans, the four-discs hoarding several diamonds-in-the-rough that never saw the light of day while the band was touring and recording, and would probably have remained locked up if Cobain hadn't killed himself in 1994. The protracted legal battles over this material were stomach churning for anyone who regarded Cobain's lyrics as a very personal buffer against life's shortcomings and disappointments, but the material itself should not be overshadowed by the greed of the living. Taken on its own, With the Lights Out sheds even more light on the immense talent and passion of the Seattle trio.

With the Lights Out

(four-disc box set)(DGC)