First things first: What’s your daemon?

That’s the single indelible detail you hold on to from Philip Pullman's His Dark Materials trilogy, first published in the US 20 years ago this month. Between rereads, you might forget why the armored bears are fighting or what makes Lyra Silvertongue run from world to world, but you always remember the fantasy of the daemon. It's a kind of externalized idea of the soul that manifests itself as an animal companion — like a pet who’s sentient, psychic, and intelligent and also part of you.

And a daemon’s species reveals something fundamental about its person’s personality. Children, with their fluid identities, have shapeshifting daemons, but at puberty a daemon settles down into a single form: a scholarly raven, a tough Arctic hare, a glamorous and malevolent golden monkey.

The fantasy of the daemon is a fantasy of self-knowledge, of completely understanding your secret, innermost self and your soul — and that makes it perfect for the philosophical, theological His Dark Materials, which is often described as Paradise Lost for teenagers. It’s a trilogy that takes the subtext of Paradise Lost, with its tragically compelling Satan and its coldly authoritarian God, and makes it text. The books are built around a war against an oppressive god, known as the Authority, and his Church; against a force that has "tried to suppress and control every natural impulse. And when it can’t control them, it cuts them out."

"Every advance in human life," Pullman writes, "every scrap of knowledge and wisdom and decency we have has been torn by one side from the teeth of the other. Every little increase in human freedom has been fought over ferociously between those who want us to know more and be wiser and stronger, and those who want us to obey and be humble and submit."

In the universe of His Dark Materials, the Church and the Authority stand for conformity, for the suppression of self-knowledge and sexuality. In contrast, the fallen angels are the side of goodness and right in the moral universe of this trilogy, and they stand for the arts and sciences, for secular humanism, and for the pleasures of the body.

His Dark Materials, in fact, insists on the pleasures of the body. It imagines a kind of tripartite human nature, one that consists of a body, a ghost or spirit, and a daemon or soul — "but the best part is the body," the books conclude. "Angels wish they had bodies."

The body is what makes Pullman’s wicked authoritarian angels envy and hate humans so; fear of the body and of sexuality is what makes the Church castrate children and cut away their daemons. And in the end, our heroine Lyra is able to save all of the worlds by reenacting Eve’s fall and learning the pleasures of the body — by, in other words, kissing a boy. It is only after Lyra and Will kiss that they become "the true image of what human beings always could be, once they had come into their inheritance."

The morality of His Dark Materials is an inversion of the traditional morality of the Christian fall, one that privileges knowledge and experience and the body above innocence and ignorance and the soul. It posits that true self-knowledge and true spirituality can only be experienced through the body.

When His Dark Materials first came out, in 1996, this idea was explosive. The Catholic Herald called it "truly the stuff of nightmares." The New York Times said the trilogy "may well hold the most subversive message in children's literature in years." At the 2007 premiere of The Golden Compass, a film adaptation of the first novel in the trilogy, the Catholic League passed out pamphlets urging Americans to boycott a franchise that "denigrates faith."

But in the 20 years since the first volume of the trilogy was published, Pullman’s theology of the body has become more widespread. Take, for instance, Carol Ann Duffy’s new adaptation of Everyman.

Everyman is a medieval morality play, written in England in the late 15th century. In the original play, Everyman (guess who he represents!) is told by God that he will soon die and be judged. Everyman asks various figures to accompany him to judgment — his friends and family, his worldly goods — but one by one, they all refuse. In the end, Everyman is only able to achieve absolution and be cleansed of his sins by repenting before God and flagellating himself. This is traditional medieval Christian morality at work: It is only by scourging his body that Everyman is able to achieve a soul clean enough to be welcomed into heaven.

But in Duffy’s adaptation, first performed at London’s National Theatre in 2015, salvation by self-flagellation proves to be a false track. Instead, Everyman is only able to accept his death and find spiritual transcendence by repeating the prayer, "For the gifts of my body I give thanks / At the hour of my death." Everyman’s ecstatic gratitude for his body climaxes in a moment reminiscent of the climax of His Dark Materials: "Praise to my tongue for snowflakes, tequila, / marzipan, mint, cheese and honey, every kiss. / Every kiss." (Marzipan, coincidentally, features prominently in Will and Lyra’s kiss.)

Like His Dark Materials, Duffy’s Everyman cannot find the sense in a theology that punishes the body. Instead, theology must be experienced through the body, and it is only through celebrating our bodies that we can experience true spiritual transcendence.

This is not an idea that would have made sense when the original Everyman was written in the 15th century, or when Milton wrote Paradise Lost in the 17th century. At that point in history, bodies were uncomfortable and disgusting; they were filthy and riddled with disease. To get closer to God, you had to transcend the body itself. You had to punish and reject it. Relatively speaking, we've only recently figured out how to comfortably live in a body, with medicine and indoor plumbing and upholstered furniture. So it's really only now that this idea of a theology of the body is finding widespread acceptance in beloved YA fantasy trilogies and in celebrated plays by Britain’s poet laureate.

And it is only with a theology of the body that the fantasy of the daemon can be born. The fantasy of the daemon is that you can hold your soul in your arms, that you can cuddle it and love it and know it with your body, the way His Dark Materials' Lyra cuddles and loves her daemon Pantalaimon. With a daemon, you can even touch your lover’s soul, as Will and Lyra touch each other’s daemons.

These thoughtful, philosophical underpinnings of His Dark Materials are what give it such legs, and have kept it alive for 20 years and counting. They are why the BBC is planning a new TV adaptation even after The Golden Compass flopped at the box office. The trilogy presents the world in ways that can be shocking when you're a child and are still compelling when you’re an adult: It grows with you in the way the best books always do.

Plus, you know, daemons and armored bears are cool.