A couple of months ago, I was browsing through a friend's record collection, comparing his most recent acquisitions to mine as we have similar taste in music. "Oh wow, you got In Utero! I only have Nevermind and the MTV Unplugged," I said, at the time still not a proud owner of Bleach. "But what I'd really like to get my hands on is a copy of Incesticide." "Yeah," he answered. "But Incesticide is not even a proper album, is it?" And as we geeked out over our favourite Nirvana albums, we rambled on how the band's collection of B-sides, demos, and covers, which turns 25 this year, is a gem in its own right. Moreover, the inclusion of Incesticide on Nirvana's album timeline proves to be an essential piece for a better understanding of their musical evolution.

I've always been a firm believer in B-sides being the key to a band's true identity, especially when said band is subject to the needs and wants of a major label and/or corporation whose single choices will inevitably rely heavily on what can be most easily propagated. This much is true, for example, on Oasis' The Masterplan (also a personal favourite of mine), whose tracks and subsequent approach inhabit a much lighter atmosphere than the one found on Definitely Maybe or (What's the Story) Morning Glory - a sonic détente that comes as a result of its inherent breathing room.

But Incesticide goes way beyond that status: it emerges as a point of reflection on Nirvana's career, whose unexpected boom - fuelled by 1991's Nevermind - catapulted them to unprecedented visibility. Incesticide is a step back, a swim to the surface for air, despite being commonly -- and cynically -- seen as a mere capitalisation on the band's success by providing new material to the world's sudden and insatiable thirst of Nirvana. But if we take a closer look, we clearly understand Incesticide has an undeniable and everlasting value that comes from its ability to combine both the past and future of Nirvana through a collection of tracks whose heterogeneity paradoxically results in its cohesiveness.

By gathering three covers from the Hormoaning EP (Devo's 'Turnaround' and The Vaselines' 'Son of a Gun' and 'Molly's Lips'), Incesticide makes us look at MTV Unplugged as its direct offspring, as it also provides a valuable insight into the band's schizophrenic list of influences, like the unexpected cover of Shocking Blue's 'Love Buzz' eventually included on Bleach, or their perfect take on VU's 'Here She Comes Now', one-half of their split single with the Melvins.

This, allied to the inclusion of other previously released tracks such as their debut single 'Sliver' (plus its B-side 'Dive'), 'Stain', 'Downer', and 'Beeswax', make for the said reflection of a not-so-distant past; the bridge to the present comes in the form of '(New Wave) Polly', which once again portrays their will to distance themselves (and their music) from any kind of sacralisation. By reinventing one of Nevermind's most beloved tracks, they embarked on a parody of self that found similar ground with their Top of the Pops performance, where Kurt sang 'Smells Like Teen Spirit' an octave below the original as a direct protest against the mandatory instrumental playback.

Incesticide also offers an impromptu glimpse into the future. With In Utero still in the works at the time, it's the album's last four tracks -- some of them coming from the band's first demo tape -- that set the tone to the acceptance of a more meditative and lyrical side to Cobain's songwriting.

While 'Aero Zeppelin''s lyrics discuss the corporate and marketing side of the music business in a similar fashion to 'Radio Friendly Unit Shifter''s ("You could shit upon the stage/ They'll be fans/ All the kids will eat it up/ If it's packaged properly"), the painful despair of 'Big Long Now' allied to the drums' faux delay anticipates the omnipresent black hole that Unplugged did a not-so-good job concealing. But it's 'Aneurysm' - whose featured version is my absolute favourite - that synthesises Incesticide's core spirit perfectly. Neither too heavy nor too melodic, the album's closer is the quintessential Nirvana song, so timeless and versatile one could argue its inclusion to be possible on any other Nirvana album. It also encapsulates the band's live energy, as this was a perfectly understandable setlist favourite.

Ultimately, it all has to do with the way you perceive Nirvana: is it as the DIY-punk breath of fresh air (Bleach)? As the grunge hitmakers whose overexposure you frown upon though deep down you know it's all about the brilliant tunes (Nevermind)? Or as the somehow decadent poets soundtracking Generation X's despair (In Utero)? Whatever your views, Incesticide gathers a bit of all the possible angles Nirvana can be observed from, uncompromisingly constituting the definite testimony of Cobain's superb songwriting skills. After all, rock'n'roll was never supposed to be taken seriously in the first place; Incesticide is a valuable reminder of that.