(Princess Diana Archive/Getty Images)

There are two events that can define a separation of generations: Where were you when Princess Diana got married? Where were you when she died?

I was a tiny toddler sitting on my young mom’s lap for the first, an awkward 17-year-old for the second. San Diego’s Starlight Musical Theatre was in the middle of a production of Singin’ in the Rain and my job was to get costumes onto cast members before they hurtled out onstage.

Somehow I learned she was dead during the performance, in the time before widespread cell phones or internet. News spread fast, through the usual backstage channels, in whispers and passed notes. The busy dressing rooms were oddly quiet. People danced off stage and started crying in the wings. Downstairs, near the costume shop, they used the pay phone to find out details from friends.

The world seemed stunned, half silent. But why? Why did we spend the next few days glued to the television and the radio? Why did we leave flowers and sing songs and feel personally affected by a woman few knew and even fewer ever understood? Who was this bashful princess, anyway? This reading list contains a few answers—but 20 years after her death, the enigmatic Diana is harder to grasp than ever.

1. “The Wedding of the Century,” by Marie Brenner (New York, August 1981)

For many, their first exposure to Lady Diana Spencer, the shy descendant of royal ladies-in-waiting and commoners, was her engagement to Charles, Prince of Wales. She was just 20 years old when it happened, which begged the question: What kind of girl snags a prince? Brenner’s breathless exposé of the most anticipated wedding of its time provides a lens for the questions that surrounded Diana when she married — and makes predictions that, it turns out, couldn’t have been farther from the truth:

Charles doesn’t seem to have thought about the ramifications of the archbishop of Canterbury’s advice about his future sex life: a good thing given by God that nevertheless, like all God’s gifts, needs to be directed aright. He doesn’t make statements telling the archbishop to mind his own beeswax. Nor does he protest the two miles of TV cables that will be in St. Paul’s. Charles is the first media prince. For him this is normal, and it’s kind of sweet how sheltered he is in the midst of the circus that surrounds him. He’s told his friends—and he means it—that he considers what will go on July 29 an absolutely private event.

His bride, who was called “Two Amp” when she was at school, in this matter is not so dumb. She comes from the real world, the world of media events and divorces, where sisters get anorectic and fathers almost go bankrupt—as hers did—and then suffer near-fatal strokes. Lady Diana escaped into fairy tales as a child—one likes to think that “Cinderella” was a special favorite—but on the matter of her wedding she harbors no two-amp illusions. She understands that this service is pure spectacle, her spectacle. She knows that well enough to have brought in the makeup woman who did A Clockwork Orange and Barry Lyndon to make sure that she will be the perfect TV bride.

For Diana Spencer, the ceremony on the morning of the twenty-ninth will represent the moment when she will finally get the ultimate security, a security never provided by the real world. Her future life will be defined by royal ribbon cuttings and court circulars in the Times, by summers at Balmoral and winters at Sandringham, by weekends at Windsor and weekdays at Highgrove. Her life will be without divorce or deviations from protocol, without ambivalence or being able to escape the obligation of having to attend an RAF show. After Wednesday noon, this twenty-year-old will never again be allowed out on the street alone.

2. Diana: In Search of Herself, by Sally Bedell Smith (August 1999)

Diana immediately set about becoming what Tony Blair later called “the people’s princess.” But though the cracks didn’t show for a while, fitting into her stifling new role was not easy.

She went through the traditional motions, producing heirs, being charitable. We all know now that the glamour was a royal façade. Tiaras, galas, and photo ops couldn’t transform a tepid marriage, one that was complicated by Charles’ longtime affair with Camilla Parker Bowles. And the public couldn’t stifle the sense that something was seriously wrong. Royals didn’t turn away from one another in public, but Charles and Diana did, And the public, so protective and conflicted about royalty felt entitled to know. In her 1999 biography, Smith revealed some of the beloved princess’ darker side.

Diana’s unstable temperament bore all the markings of one of the most elusive psychological disorders: the borderline personality. This condition is characterized by an unstable self-image; sharp mood swings; fear of rejection and abandonment; an inability to sustain relationships; persistent feelings of loneliness, boredom, and emptiness; depression; and impulsive behavior such as binge eating and self-mutilation. Taken together, these characteristics explain otherwise inexplicable behavior. Throughout her adult life, Diana experienced these symptoms severely and chronically. While she received periodic treatment for some of her problems—her eating disorder and her depression—neither Diana nor anyone close to her came to grips with the full extent of her illness.

4. The Diana Chronicles, by Tina Brown (June 2007)

Her darker side may have been well hidden, but Diana used her unprecedented visibility to bring attention to some of her era’s most pressing causes. She could change hearts and minds with a simple hug or handshake, as when she helped reduce stigma toward HIV/AIDS by daring to touch patients in public. During the last year of her life, she toured countries with landmines to raise awareness, created a landmark television special, and made a controversial land mine ban a pet project. Brown exposes the savvy that Diana brought to the cause.

Diana’s land-mine commitment was not, to use one of the Queen’s favorite pejoratives, a “stunt.” It drew forth everything that was best about her in the service of a cause that was heartrending, underpublicized, and controversial. Chased in Angola by the press the day after the Tory smoke bombs went off in London, Diana did not engage in argument. “It’s an unnecessary distraction…It’s sad…I’m a humanitarian, not a politician.”

And, indeed, few politicians would have had the courage to do what she did next. The Red Cross had decided that it was too dangerous to go to Cuito, believed to be Africa’s most heavily mined town, which was laced with booby traps. Seven children had just been killed playing soccer in an area that was supposed to have been cleared. But Diana would not hear of canceling. She pressed Whitlam, who was anxious about her safety. She lobbied the wife of the president of Angola. And the next day she was in Cuito and then in nearby Huambo, in a visor and body armor over a white cotton shirt and khaki pants, ready to be delicately guided through another allegedly cleared area—even though exposed and half-extracted mines were visible. The staff of the halo Trust, a British charity that clears mines, warned her to stay close to them. “I think by the end of the briefing she was beginning to wonder whether this was a good idea,” said Whitlam. “But she did it.”

4. “The Diana Mysteries,” by Tom Sancton (Vanity Fair, October 2004)

Her personal magnetism, media savvy, and the bravery in the face of the world’s most visible divorce endeared Diana to the world. And after her death, the circumstances of her fatal car crash became just as intriguing as the details of her life. It’s the stuff of a million conspiracy theories, and according to Scanton, there are deeper reasons to care about why, and exactly how, Diana died.

It was probably pericardial strangulation, rather than internal bleeding, that caused Diana’s sudden cardiac arrest in the tunnel.

“The damage to her heart had already happened and her death would have been inevitable at this point,” he says. “Even in the best of trauma centers, this rare condition would have been difficult to diagnose and treat—in most cases, it is only discovered at the time of autopsy. I think the result would have been the same in any trauma center in the U.S.—even if she had been brought to the emergency room 15 minutes after the accident.” If Mattox’s theory is correct, then the French were probably right to say Diana could not have been saved.

“But if Diana was doomed in any case,” I ask Mattox, “what difference does it really make to know that she died of cardiac strangulation?”

“Informing the world of the total truth puts this thing to closure,” he says. “The world is looking for closure. We never reached it on J.F.K., but maybe now we can on Diana.”

5. “Royal Bodies,” by Hilary Mantel (The London Review of Books, February 2013)

It’s chilling, our desire for graphic descriptions of Diana’s wounds, of the way she took her last breath. But then, so is the entire idea of Diana. Dissected and dramatized, her death has brought out uncomfortable truths about both the fallen princess and our obsession with fame.

Nobody captures that better than Mantel, whose examination of Diana and Kate as carefully monitored baby machines puts The Handmaid’s Tale to shame. She also captures the strange atmosphere of mourning the world put on after her death.

You could read a lot about the ways we mourned Diana, from Charles Nevin’s sensitive obituary to her brother Charles’ fierce eulogy to Peter Bradshaw’s telling essay on why her death was so ghoulishly exciting. But Mantel’s description of Diana might be the most disconcerting — and true.

For a time it was hoped, and it was feared, that Diana had changed the nation. Her funeral was a pagan outpouring, a lawless fiesta of grief. We are bad at mourning our dead. We don’t make time or space for grief. The world tugs us along, back into its harsh rhythm before we are ready for it, and for the pain of loss doctors can prescribe a pill. We are at war with our nature, and nature will win; all the bottled anguish, the grief dammed up, burst the barriers of politeness and formality and restraint, and broke down the divide between private and public, so that strangers wailed in the street, people who had never met Diana lamented her with maladjusted fervor, and we all remembered our secret pain and unleashed it in one huge carnival of mass mourning. But in the end, nothing changed. We were soon back to the prosaic: shirtsleeves, stacking chairs, little sticks. And yet none of us who lived through it will forget that dislocating time, when the skin came off the surface of the world, and our inner vision cleared, and we saw the archetypes clear and plain, and we saw the collective psyche at work, and the gods pulling our strings….

In looking at royalty we are always looking at what is archaic, what is mysterious by its nature, and my feeling is that it will only ever half-reveal itself. This poses a challenge to historians and to those of us who work imaginatively with the past. Royal persons are both gods and beasts. They are persons but they are supra-personal, carriers of a blood line: at the most basic, they are breeding stock, collections of organs.