David Bottrill was sitting in Maynard James Keenan’s apartment with the Tool singer’s cat on his lap when Maynard unleashed a blood-curdling scream. Except it didn’t stop. On and on it went: 5, 10, 25 seconds. Finally, after nearly half a minute, the noise stopped.

“I was sitting at the computer recording vocals, with Maynard behind me. I didn’t have a camera or a mirror, just this cat on my lap,” David recalls now. “He starts to scream, and it’s going, and it’s going… At the end, I turn around and Maynard’s on his knees, completely spent. It was the first take. Just one take, and that was it.”

It was 2000, and the pair were recording vocals for The Grudge, the song that would open Tool’s third album, Lateralus. It was a fittingly intense moment. When it finally dropped on May 15, 2001, Lateralus marked the end of a gruelling five-year period for the band, during which time they’d been pinioned by a crushing legal battle with their then-label that had left their future anything but certain.

Lateralus was a huge release of energy and emotion – a 79-minute, spiritually charged behemoth, bursting with dizzying time signatures, seismic riffs and themes of isolation, vulnerability and connection. Twenty-five years on, its impact can still be felt.

In 1997, while touring in support of their second album, 1996’s platinum-selling breakout Ænima, Tool were slapped with a lawsuit from their label, Volcano Entertainment, alleging contract violations. It was the start of a war of attrition that brought on total creative paralysis, as much a psychological battle as a legal one.

“It was a very grating period, having this ‘lawsuit fog’ hanging over us for years,” bassist Justin Chancellor explained in a 2001 interview on MTV2. “But in a way, it forced us to look inward and really solidify as a unit. We had to fight to even be allowed to create, and I think you can hear that struggle and the eventual release of it in the music. It wasn’t just about making a record anymore; it was about survival.”

By the end of 1998, agreements were drawn up and the legal drama ended, freeing the band to return to the studio, which they did with a heightened sense of purpose.

“We had a couple records under our belt and lots of touring,” guitarist Adam Jones told Revolver in 2022. “By that time, we knew our limits. We knew what stuff we could push. We were a well-oiled machine. And we knew each other. And there were things we learned about each other on that record that are pivotal to this day.”

The musical landscape had changed radically since Tool emerged at the start of the 1990s. Many of the bands they’d once shared stages with had splintered or split.

“Alice In Chains, Helmet, Soundgarden, Nirvana, and now Rage [Against The Machine],” said drummer Danny Carey in 2001. “It’s really kind of amazing that all of them are gone. It’s a strange feeling to look around and realise we’re still here. But I think that sense of being the survivors gave us a certain freedom. We didn’t feel like we had to fit into a scene anymore, because the scene didn’t really exist. We just had to answer to ourselves.”

Now more than ever, Tool were marching to their own complicated beat. At the dawn of the 2000s, progressive rock seemed like a bloated relic of a bygone age. A handful of groups – Dream Theater chief among them – were flying the flag for complex, ambitious music, but bands and the public alike seemed largely immune to prog’s charms. Why listen to old dudes in capes when you’ve got Korn and Limp Bizkit?

By contrast, Tool cast their gaze back to the progressive giants of the 70s, particularly King Crimson. Led by the exacting, innovative visionary Robert Fripp, Crimson were the architects of a disciplined, professorial strain of music that prioritised knotty polyrhythms and structural subversion over traditional riffs. With songs such as 1969’s proto-prog metal classic 21st Century Schizoid Man, they proved heavy music could be high-art, trading musical excess for a clinical, forward-thinking precision that redefined the boundaries of the genre.

“We pulled quite a bit of King Crimson into what we’re doing,” Maynard explained in 2001, adding: “I think we’ve brought in a much more vulnerable, emotional element that was missing in King Crimson. Which is good. I would hope that that’s something that they could recognise and… be the master in the corner that nods silently: ‘Very good work.’”

“Tool were one of the greatest bands to take influences from so many different styles and blend them into something completely unique,” says David Bottrill.

“I think you hear King Crimson in the songwriting structure, in the way that Adam builds his tone, and in the way Danny listened to both [King Crimson drummers] Bill Bruford and Pat Mastelotto. It’s also the Led Zeppelin influence Adam had from doing No Quarter [the 1973 Zeppelin song covered by Tool during the Ænima sessions that was eventually released in 2000]. Working on those sonics and that structure amalgamated into what Lateralus became.”

Tool began work on the follow-up to Ænima in the autumn of 2000. They took a different approach to the way they’d made the previous record: where the writing process for Ænima had seen Maynard forging melodies and lyrics alongside the music being created by Adam, Danny and Justin, this time the instrumental trio began poring through four years’ worth of riffs, melodies and ideas while Maynard more or less left them to it.

“They would have a whiteboard and go, ‘OK, well, let’s go from Riff A to B to C,’” explains David Bottrill, who had produced Ænima, and was on board once again for Lateralus.

“They would just work things around, try many different options of arrangements to see which ones felt the best.”

Maynard, for his part, spent much of 2000 on the road with his side-project A Perfect Circle while his bandmates worked. His stance, as David recalls, was one of blunt pragmatism:

“‘Look, you guys get the arrangements sorted out… send it to me when you’re closer, then I’ll work on the lyrics.’”

The songs that resulted achieved a rare balance between technicality and humanity, where the intricate musical arrangements never choked out the raw, visceral pulse at the centre of it all. Thematically, Lateralus ditched the cynical edge that had partly defined Ænima and their 1992 debut EP Opiate for a radical, wide-eyed vulnerability. Maynard framed the album as a “spiritual roadmap” designed to transform toxic energy into transcendence.

“If I have a spiritual side, it’s about trying to be as honest as I can,” he noted at the time. “The one thing that was missing from that very heady, artistic progressive rock approach was the emotional… we didn’t seem very ‘vulnerable.’”

That approach was encapsulated by The Grudge, the album’s eight-and-a-half-minute opening track and the song on which Maynard unleashes that monumental scream heard by David Bottrill and a cat.

Lyrically, it’s the singer’s warning against what he called the “lead weight” of grievances that drag the soul under. It’s seemingly loaded with both alchemical and astrological symbolism: Tool-watchers have suggested the line ‘Saturn ascends’ refers to the time it takes Saturn to orbit the sun, around 29.5 years.

Maynard has never revealed the specific significance of that line, though he did say that the track was a conscious decision to choose “the transformation of negative energy into positive energy” over the easy payoff of rage.

Musically, Lateralus dispenses with any remnants of the marginally more straightforward alt metal sound with which Tool made their name in favour of music that is complex and expansive.

Schism is defined by a coiling, serpentine bassline and a constant rotation of odd time signatures, The Patient uses restraint as a weapon, its slow burn mirroring the very process of the existential survival that birthed the record, while the transition from the ethereal Parabol into the earth-shaking Parabola remains one of heavy music’s most devastating payoffs, its tension slowly building until it has no choice but to explode with the force of a neutron bomb.

The mid-album firestorm Ticks & Leeches hits like a high-velocity exorcism, pushing Maynard to a level of vocal strain that purportedly sidelined his ability to sing for weeks. The album’s final descent is the 25-minute suite of Disposition, Reflection and Triad, which trade sheer force for a trancelike, Jungian exploration of ego-death and spiritual realignment.

Beyond the sprawling song structures, the band still left room for moments of eccentric experimentation. This manifested in the album’s atmospheric segues, most notably on the track Mantra. Though it sounds like a deep, meditative hum, Maynard later revealed to the Japanese magazine Buzz that the recording was actually a “treat” for fans: the sound of him squeezing his Siamese cat, slowed down until the animal’s protest became a cavernous, ambient pulse.

It wasn’t the only found sound to make the cut. Elsewhere, Danny Carey growled through a tube to simulate the chanting of Tibetan monks for Parabol, and the album’s closer, Faaip de Oiad, utilises a sampled 1997 radio call to Coast To Coast AM from a man claiming to be a panicked, former Area 51 employee – a paranoid interlude that tapped into “the sheer frequency of human desperation”, as described by Maynard.

But the album’s most famous Easter Egg is embedded in the album’s title track. The Fibonacci sequence is an ancient mathematical pattern in which each successive number is the sum of the two that precede it. Somehow, Tool found a way to work it into one of their songs.

“Justin brought in this amazing bass riff,” Adam recalled. “He said, ‘The first part’s in 9, the second part’s in 8 and the last part’s in 7.’ Danny was like, ‘[987] is a number of the Fibonacci. That’s really cool.’… We told Maynard, and he went, ‘Oh, my god, I’ll write my lyrics like that!’”

The singer’s vocals follow this pattern, each syllable representing a number in the series. It’s a very clever arrangement that has, over time, been wildly mythologised and over-emphasised by those hungry for esoteric secrets. Maynard himself has spent years trying to deflate that particular balloon.

“I feel like I kind of pulled a very pedestrian, sophomoric move,” he told podcaster Joe Rogan in 2017. “It’s good to let people know about [Fibonacci] but it was kind of a dick joke, in a way. I could do better.”

Intellectual dick jokes notwithstanding, the album sounded like nothing else that had come before. It was closer in spirit to Radiohead’s Kid A, released the previous year, than any contemporary metal band.

Just like Kid A – another album that refused to play by the music industry’s rules – Lateralus proved that mainstream success didn’t have to come at the expense of intelligence and vision.

Yet Tool weren’t completely exempt from having to play the game. Schism was released as a single at the start of 2001, a taste of what was to come. Even so, it was a defiant choice for radio.

“I found it very hard when we came to pick a single,” Justin told Prog magazine in 2021. “Adam and Danny immediately were like, ‘Schism is the hit, that’s the one, everybody is going to love it.’ I was honestly really on the opposite end of that. ‘Really? It’s so odd.’”

The gamble paid off, with the song’s success amplified by a disquieting stop-motion video directed by Adam that featured no footage of the band. Justin credited this to the group’s refusal to sign away their autonomy, noting that the guitarist’s background in special effects allowed them to ignore the industry’s demand for a typical rock promo.

“Nobody gets to tell us what to do at all,” Justin said. “We never felt under pressure to make a typical rock video with the band jumping around onstage.”

Nor was the album’s packaging comparable to anything their contemporaries were doing. For the artwork, they enlisted artist Alex Grey, whose anatomical, translucent illustrations – rendered in a multi-layered, clear plastic booklet – mirrored the album’s obsession with peeling back layers of the self to reveal the luminous spiritual core beneath.

“Alex has a way of visualising the things we were trying to articulate lyrically,” explained Maynard. “It’s that sense of a ‘spiritual roadmap’. When you look at the layers of the Lateralus booklet, you’re literally peeling back the physical to find the light inside. It perfectly captured the intent of the record: the idea that we are more than just these meat-suits.”

When Lateralus itself landed in May 2001, it dashed any hopes or expectations for an Ænima Pt. 2. Critics were predictably split. While Metal Hammer praised its “proper serious heavyweight rock” as being on par with Led Zeppelin’s equally epic Physical Graffiti or Pink Floyd’s The Wall, chronically petulant hipster music website Pitchfork issued a baffling 1.9/10.

By that point, Tool were critic-proof anyway. This sprawling, cerebral monolith demolished the competition, debuting at No.1 on the Billboard 200 and selling a jaw-dropping 550,000 copies in its first week, beating the likes of Missy Elliott and Destiny’s Child.

In the years since its release, Lateralus has taken on a life beyond the band. Fans had proposed alternate track sequences, dived deep into the album’s vast numerical realms, and come up with some truly head-scratching theories, like the one claiming the band wrote Lateralus along to the film The Passion Of The Christ, a movie released three full years after the record.

Adam recalls first hearing about that theory from a fan email: “I wrote her back and said, ‘Cool. You figured it out.’”

The factual impossibility was beside the point. The engagement wasn’t. Within the scene, Lateralus emerged as a beacon for what prog metal could become. While some bands simply mimicked Tool’s technical quirks to infinitely lesser effect, acts such as Mastodon took the album’s spirit of ambition to forge their own conceptual paths on albums like Leviathan.

By clearing a space for atmosphere and experimentation, Tool provided a vital blueprint for the challenging music made by the likes of Gojira, The Ocean and Tesseract.

“Lateralus redefined what heavy music can be,” says David Bottrill. “There’s nobody that sounds quite like them. I can tell you, you’ve got no idea how many demos I get that are pastiches of what they do, and nobody comes close.”

Perhaps Danny Carey himself put it best: “It still makes my hair stand on end when I listen to it alone in the dark.”

Iron Maiden have announced that they will complete the filming of their forthcoming Run For Your Lives tour documentary at their much anticipated Eddfest show at Knebworth.

As previously reported by Metal Hammer, the East London band had originally planned to centre the film around their June 22 show in Paris in front of 30,000 fans at the La Défense Arena in Paris, but they were forced to play a shortened set in the French capital due to a power outage in the city.

To comply with a strict 11:30pm venue curfew, Steve Harris’ band were reluctantly forced to drop three proposed encore songs, Aces High, Fear Of The Dark and Wasted Years., from the show, much to their disappointment. But quoted in a post-gig press release, frontman Brice Dickinson promised “like every other challenge Iron Maiden have faced over the years, we’ll find a way to deal with and overcome the missing songs in the encore when it comes to the final film.”

The solution to the problem will now ensure that the upcoming Eddfest show will now be captured by the film-makers for posterity.

Band founder and bassist Steve Harris comments, “You all know what happened in Paris, we all know what happened in Paris, so we’re gonna finish it off at Knebworth, and we’ll see you there.”

Bruce Dickinson adds, “We’re not going to lose what we did in Paris but we’re going to add to it with some amazing stuff from Knebworth. So Knebworth, be on ya best behaviour!!”

The Knebworth spectacular is the concluding show of the band’s European Run For Your Lives tour. The East London metal legends will headline the second day of Eddfest, with The Hu, The Darkness, Airbourne, The Almighty, and former Maiden frontman Blaze Bayley also on the lineup.

“This weekend is for you, our fans,” says manager Rod Smallwood. “We are trying to do something special and a bit different in celebration of 50 years– a full on Maiden experience from the moment you arrive on site to the minute you leave. And of course, a very special couple of days for the campers, and I will certainly join them both nights, as I don’t want to miss anything!. So enjoy it, try to get to see and be part of a bit of everything, and I’ll see you in the bar!”

Maiden are on the the cover of the latest issue of Metal Hammer magazine, which comes with an exclusive Eddfest water bottle! Get the issue here.

Classic Rock and Metal Hammer have also teamed up with Maiden to create a killer-collectible: the official programme and museum guide!

Eddited by Iron Maiden Fan Club Edditor Alexander Milas, the programme features exclusive interviews, Steve Harris looking back at over 50 years of heavy metal mayhem, plus the official guide to the Infinite Dreams Experience, the open-air Maiden Museum full of stage props and Maiden memorabilia collected over a half-century of historic tours. Pre-order it here.