Simon’s excellent, sinuous single, which hit #1 in 1973, was probably the peak of her career: as critic Ellen Willis said, it proved rock ‘n’ roll was so democratic, even a rich person could make a great single. (Simon’s father was Richard L. Simon, the cofounder of the publishing house Simon & Schuster.) The song was addressed to a rich, self-involved ex-boyfriend, prone to philandering, placing winning bets at the Saratoga racetrack, and flying Lear Jets up to Nova Scotia. “You’re so vain / You probably think this song is about you,” Simon sang in the chorus.

So who was Simon holding up a well-polished mirror for? Speculation has centered, reasonably enough, around Simon’s real-world ex-boyfriends: Mick Jagger, Warren Beatty, Kris Kristofferson, and Cat Stevens–plus James Taylor, whom she had married a month before the song hit the airwaves.

Let’s start with Mick Jagger, who provided backing vocals on the song. If he was, in fact, the subject of the “You’re So Vain,” that would either mean that Simon had deviously tricked him into singing on the track or that he was just so arrogant that he didn’t care who knew how vain he was. Simon says that originally Harry Nilsson was going to do the background vocals, but that when Jagger dropped by the London studio to say hello and pitch in, Nilsson graciously stepped out. Asked point-blank in 2001 if it was about Jagger, Simon said, “Oh, no, no, no.”

So maybe it was about the famously vain Warren Beatty, then? Simon says that Beatty certainly thought so; after the song came out, he called up Simon and thanked her for writing it about him. (And arguably, anyone who genuinely believes the song is about himself is vain enough that the song should be about him.) A Washington Post interviewer asked Simon in 1983, “You had gone with [Beatty]?” Simon replied, “Hasn’t everybody?” “No,” the interviewer replied. “That only means you haven’t met him,” Simon said. “At the time I met him, he was still relatively undiscovered as a Don Juan. I felt I was one among thousands at that point—it hadn’t reached, you know, the population of small countries.” In 2000, Simon said, “It’s certainly not about Warren.”

Simon’s also specifically ruled out James Taylor (“It’s definitely not about James”). In an interview with Rolling Stone in 1973, soon after the song’s release, she said, “James suspected that it might be about him because he’s very vain.” Apparently, soon after the song’s release, Taylor had the discomfiting experience of taking a jet plane to Nova Scotia; fortunately for him, it wasn’t a Lear.

At various points, Simon’s suggested that the song was actually inspired by three or four different people. Just as consistently, however, she’s talked about a specific person being the subject of the song. She could, of course, be engaging in intentional misdirection, but it seems more likely that one particular ex was the inspiration for the song—and that she then garnished that portrait with aspects of some other past paramours, and maybe invented a few details as well. Despite the contrary claims of the lyrics, there may have never been an apricot scarf.

After thirty years of keeping the gavotter’s identity a secret, Simon sold the information in 2003 to the high bidder in a charity auction benefiting Martha’s Vineyard Community Services. The winner: Dick Ebersol, the NBC Sports president (and one of the executives behind the launch of “Saturday Night Live”). For $50,000, Simon invited him and nine of his friends over to her house, performed the song, swore them to secrecy, and told them who it was about. (In the ensuing wave of publicity, she gave the coy clues that the subject’s name contained the letters E, A, and R—which would eliminate Cat Stevens and Kris Kristofferson, but not Jagger, Beatty, or Taylor.)

Not sworn to secrecy, apparently: her husband since 1987, Jim Hart. In 2005, he told a small New York newspaper that “You’re So Vain” was not about any well-known name—just an old boyfriend of no particular notoriety. This makes sense on a number of levels: Simon could easily have had a jetsetter boyfriend before her singing career took off, and when she said in 1973, “I can’t possibly tell who it’s about because it wouldn’t be fair,” she might have meant that she didn’t want to pull a civilian into the spotlight unwillingly. And of course, she’s smart enough to know that speculation about Jagger and Beatty is more titillating than the reality. Or as Simon put it, “I could never really solve it because if I did, then no one would have anything to talk to me about.”

(Excerpted from the 2006 book Is Tiny Dancer Really Elton’s Little John?: Music’s Most Enduring Mysteries, Myths, and Rumors Revealed, published by Three Rivers Press, written by Gavin Edwards.)