As R.E.M. sprinted toward a long-developing commercial breakthrough in 1987, they came to more fully understand their powers as a band – both musically and socially. They also came to terms with everything they’d left behind, a workaday existence where nothing is guaranteed.

And all of that happened within “Finest Worksong,” the opening cut on Document. “The minute we wrote that,” Peter Buck said in Reveal: The Story of R.E.M., “we pretty much knew that it had to be side one, track one.”

Document reached the Top 10 on Billboard‘s album chart, a first, even as the band prepared for a shift from indie I.R.S. Records to the major-label exposure provided by Warner Bros. They ended up reeling off five straight Top Five studio projects in the early ’90s, including two chart-toppers, but this is where R.E.M. officially made the transition from college-rock upstarts to mainstream rockers.

“Finest Worksong” showed they weren’t shying away from it, either. This riffy, U2-esque statement of populist purpose blended radio-ready, largely improvised sounds with a new lyrical assertiveness. The intent here, Michael Stipe said in Reveal, was to attack “the idea that you can work and work, and get what you want, and then try for even more. It’s the American dream, but it’s a pipe dream that’s been exploited for years.” He seethes with anger while singing lines like, “What we want and what we need has been confused.”

This topical bent was a new development for a band that had largely avoided politics early on, choosing instead to couch their intent in elliptical phrases and just as elliptical guitar figures. They tended to walk a fine line, partly because of a reluctance to be seen as dilettantes, and also to keep some sense of mystery around the songs. “I don’t like sloganeering, especially when it gets to something like the Clash who don’t know what they’re talking about,” Buck once said. “They’re fucking boneheads. People think that’s revolutionary, and it’s garbage!”

By 1984, however, R.E.M. was turning a corner, as Stipe began to engage in the issues of the day during extemporaneous comments on stage. Document showed they were now ready to fully integrate those steadfast beliefs into their musical narratives, as well.

“Rock ‘n’ roll is supposed to be about personal freedoms,” Buck told UPI in 1987. “How can you do this and act like a clown, jump around in striped trousers, and then just go home and not worry about it because you’ve got your million? That’s just sickening. I’m not saying you have to make social messages, but the Motley Crues and Van Halens, they have a tool to talk to every disenfranchised lower-middle-class kid who works in a garage and tell them something about what’s happening to them – but all they tell them is ‘go ahead and jump.’ A lot of these bands make it on rebellion, but it’s really safe rebellion. All the kids raise their hand in the air and yell and drink a bunch of malt liquor for about three hours, then they go right back home and go to the mall.”

Buck began by banging on a B-string, then R.E.M. leaped into a groove when bassist Mike Mills joined the proceedings. Everything fell into place musically on “Finest Worksong” as that initial run-through unfolded.

Watch R.E.M.’s ‘Finest Worksong’ Video

“When I brought it in, I felt like I knew what I wanted to and kind of vaguely knew what the guys should do, but we played it once and it just kind of came out of nowhere,” Buck wrote in the liner notes for Part Lies, Part Heart, Part Truth, Part Garbage 1982-2011. “Mike and [drummer] Bill [Berry] have always been particularly good at coming up with stuff off the tops of their heads that’s kind of amazing. It sounded great, but I was afraid that Michael might have trouble writing to it, just because it’s a B note. That whole song is in B, except for the chorus. It reminded me of touring with the Gang of Four. It kind of had that vibe to it.”

With nothing left to complete “Finest Worksong” save for the appropriate lyric, Stipe didn’t disappoint – holding fast to a unique, intriguingly associative lyrical approach that was very much in keeping with their dream-based name. We hear him admonish the listener, for instance, to “take your instinct by the reins / Good, better, best to rearrange.”

“Some of the songs are incomplete, and that’s OK,” Stipe told the New York Times in 1987. “I’ve never felt the responsibility to write every song so that it makes perfect sense from beginning to end. But some that have been considered inscrutable and incomprehensible are utterly there. If someone really investigates a song, I like for there to be something there.”

That might be best heard within R.E.M.’s reference to Henry David Thoreau, the 19th-century poet: “To throw Thoreau, and rearrange.” A friend had told Stipe that he “was our generation’s [fellow poet Walt] Whitman, I think because I was an ecstatic, and I liked men and women, and I was a poet in his eyes – even though I hated the word poet,” Stipe wrote in the liner notes for Part Lies, Part Heart, Part Truth, Part Garbage. “Anyway, I meant to write Whitman into the song, but I got mixed up and wrote Thoreau in instead.”

This approach gave fans plenty of openings to find their own stories within the music. It also allowed R.E.M. to push back against misconceptions. When a protester tried to link “Finest Worksong” to the Gulf War, shouting, “The time to rise has been engaged,” Stipe responded with another R.E.M. lyric. “Not everyone can carry the weight of the world,” he said, quoting 1983’s “Talk About the Passion.”

If all else failed, you could simply enjoy “Finest Worksong” as a great moment in indie rock – emphasis on “rock.” That was a goal here for R.E.M., who took over as first-time producers. Their 1984 album Reckoning had a tiny notation on its spine that read, “File Under Water.” The message on Document? “File Under Fire.”

“We were becoming more confident in our ability to play, to pull off whatever we wanted to try,” Mike Mills told David Daley in the liner notes for a Document reissue. “In this case, we wanted to try and come out strong and be loud. We wanted to incorporate some of the angularity, some of the muscle, some of the things we’d seen and learned in touring.”

It was all starting to come together for R.E.M.