It's easy to look at Blackstar as David Bowie's darkest album. After all, it immediately preceded his demise after a secret bout with cancer. But Heathen, released on June 11, 2002, actually dug far more deeply into the notion of aging and death – and did so far more explicitly, too.

Heathen took shape at Allaire Studios in upstate New York just before 9/11, though the tragedy hangs like a heavy shroud over the entire album. We find Bowie once again attempting – as with the earlier triumphs like Station to Station – to discern some rhyme or reason amongst life's inevitable chaos.

"My entire career, I've only really worked with the same subject matter," he told the AP in 2002. "The trousers may change, but the actual words and subjects I've always chosen to write with are things to do with isolation, abandonment, fear and anxiety."

This time, however, the issues came from within, rather than without: How to cope with the slow decline of aging, the lingering injustices that threaten our humanity, the legacy we leave behind for future generations. If Bowie's earlier personas were trapped in some form or another of outer space, this one was searching the darkened corners of our inner feelings.

"He would go somewhere in the mornings, when he was writing these songs," producer Tony Visconti said in Strange Fascination: David Bowie - The Definitive Story. "You could see he was really struggling with questions. After a few weeks, I said: 'It seems like you're addressing God himself.' The concept of Heathen was a godless century. He was addressing the bleakness of our soul – and maybe his own soul."

First, Bowie would have to deal with his own history, head on. Visconti was returning for the first time since their 1980 collaboration on Scary Monsters. Together, they'd created a string of celebrated studio projects, among them the Berlin Trilogy.

"We didn't want to repeat what we did in the past, because people hold our albums in high esteem and we didn't want to cheapen that," Bowie told MTV in 2002. "It was on my shoulders to produce structures lyrically that were strong enough to produce an autonomous piece of work, so that we didn't have to pull back into the past."

Hints of what came before inevitably bubbled up. "Slip Away" connects instrumentally with "Space Oddity," as Bowie returns to the stylophone organ. "Slow Burn," which asks "who are we in times such as these?" amid an eruptive solo by Pete Townshend, connects emotionally with "Heroes." The tour that followed paired these new songs with a full reading of 1977's Low, also from the Berlin albums.

"We do know, between us, how to landscape a song and give it a real place, an identity and a character," Bowie admitted in a 2002 talk with the New York Times. "I guess that's the vestiges of the more theatrical things."

Listen to David Bowie Perform 'Slip Away'

At the same time, Heathen worked hard to find fresh musical purchase, blending the familiar with newer conceits inside the dim ambience "Sunday," the deceptive buoyancy of "A Better Future," and a surprising trio of cover songs highlighted by the Pixies' "Cactus." Not as downbeat and closed off as 1999's Hours, or as experimentally contemporary as 1997's Earthling, Heathen beat a confident path in between.

"I suppose, for me, [Visconti is] always great when stuff tends to be experimental," Bowie told the Tampa Bay Times in 2004. "I went into the writing mode for Heathen not really knowing what I’d be doing. He’s a great guy to let the artist run with whatever’s on his mind. It’s a very liberal working process with Tony."

The album is bookended by hushed songs that face mortality with a quiet determination. And like "Slow Burn," the concluding title track seemed to presage the swirling despair that followed the 2001 attacks on his adopted hometown. Especially when he sings: "Still on the skyline, sky made of glass/ Made for a real world, all things must pass."

In reality, however, the intent was much more personal. "Heathen (The Rays)" is "about knowing you're dying," Bowie told Rolling Stone in 2014. "It's a man confronting the realization that life is a finite thing, and that he can already feel it, life itself, actually going from him, ebbing out of him, the weakening of age."

Still years away from his cancer diagnosis, Bowie nevertheless made his own concessions to such things: He took a minimum amount of time away from home, where he and wife Iman were caring for a two-year-old daughter. During a headlining tour with Moby that summer, he returned to Manhattan between every one of six East Coast dates.

Yet contentment, if anything, made Bowie peer more deeply into his own fears. "Slip Away," as its title suggests, was a moment of gorgeous melancholy. But "Everyone Says Hi," like "A Better Future," eventually revealed itself as an indescribably sad song about loss, too. "The Angels Have Gone," with its heartbreaking line "we never talk anymore," was dedicated to the recently passed Who bassist John Entwistle.

Bowie would turn to more positive ruminations on the 2003's Reality, a true post-9/11 record. "Ironically, the sad and more poignant and, in a way, more introspective piece was Heathen – which was before the event," he told the Tampa Bay Times. But neither strayed too far from the core topics that Bowie admitted to exploring across the length of his career.

"When it's taken that nakedly, these are my subjects," Bowie told the New York Times. "And it's like, well, how many times can you do this? And I tell myself, actually, over and over again. The problem would be if I was too self-confident and actually came up with resolutions for these questions. But I think they're such huge unanswerable questions that it's just me posing them, again and again."

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