At the heart of every last one of Diana Wynne Jones' fantasy novels—I've never read a book of hers that wasn't extraordinary—lies two profound ideas.

First: that the world is stranger, more chaotic, and more confusing, in ways both sinister and wondrous, than we believe it is. (Jones spoke of how her childhood experiences living through World War II in Great Britain, and watching the absurd and bizarre ways that the adults around her responded to it, gave her the sense that "normalcy" was a myth at best.)

Second: that we take the world in all its madness for granted. Whether our experiences are typical or extraordinary, we come to the conclusion that this is just the way things are, and usually hold onto those beliefs through adulthood.

Children, in Jones' stories, take magic for granted, whether or not they should. Magic is one of many reasons why they might find the world confusing; it's one explanation among many as to why the world is what it is. Sometimes children mistake magic for natural phenomena—and sometimes they confuse natural phenomena for magic. One of the many tricks Jones likes to play on her readers is flat-out asserting that certain magical properties are true in a story, then revealing on that those rules were bullshit. Or she'll present a scenario as completely ordinary, thoroughly realistic, only to explain later that some supernatural force was behind everything we believed to date.

If Diana Wynne Jones wrote primarily about children, perhaps it's because childhood is where we most find ourselves trying to figure the world out—where we're sorting out the rules, discovering patterns, and determining for ourselves what sanity and reasonableness most look like. And when Jones writes adults, they often fit one of two patterns: either they've learned to approach the world with uncertainty, curiosity, and wonder, or they're so convinced of their own understanding that they become annoying or monstrous or both.

I've thought a lot, over the last decade, about a passage from her excellent novel Witch Week, in which a young boy encounters a witch-hunting inquisitor and understands the horrible, surreal injustice of witch burnings for the first time:

Jones writes, more explicitly and intricately than she lets on, about power. Children are, in many ways and forms, powerless; they live in a world which has been shaped for them by others, and have no choice but to trust what they are taught. The people who hold power, meanwhile, hold it for reasons that often have little to do with wisdom, knowledge, or good intention. Evil, for Jones, is never glamorous or compelling: it's dull and irritating and stupid and awful, and none of that matters, because there's no rule that keeps stupid, awful, irritating dullards from inflicting themselves upon the innocent and the ignorant alike.

While she wrote a few fascist dystopias in her day, Jones rarely focuses on a grand, sweeping sense of oppression: her focus is on the people who grow up in these horrible, oppressive worlds, too preoccupied with what is to mourn what could have been. When she depicts monstrous people, it's with a sense that they're too dim to imagine the horrors of their own actions: to them, they are merely acting as one acts, deaf to the senseless cruelties they inflict.

The counterpoint to these horrors is rarely idealism or principle or a sense of justice: it's open-mindedness and wonder. If the world is capable of unthinkable barbarism, it also holds a near-infinite capacity for novelty, originality, discovery, playfulness, joy. Evil, in the end, is finite; the forces that oppose it, however scattered and confused and unprincipled they might be, have an endless ability to conceive of something new. And that sheer possibility reduces all the evils in the world to abject senselessness: why bother, Jones asks, with all the terrible monotonous nonsense of the world as it exists today, when you could be out discovering everything else it might become?

Hence magic, which in Jones' hands is a crucible in which new kinds of worlds are born. Magic, in a Diana Wynne Jones novel, is rarely orderly or makes particular sense: it is innately extraordinary, capable of more than the reader will witness or fully comprehend. Every novel Jones ever wrote seems to invent a brand-new flavor of magic, and a new scintillating universe shaped by whichever magic came to her mind. It defies order, defies tedium, defies sensibility: it is the world as we understood it when we were young, which is to say it is everything in the world that we cannot possibly comprehend. Its purpose is to give birth to hypothetical new societies, and then to thwart those social orders the moment we think we know what we're looking at.

Witch Week, which takes place in a world identical to ours but with far realer witches, is book four in The Chronicles of Chrestomanci, which is the longest (and one of the only) series that Jones ever wrote. Unlike most fantasy sagas, each book in the Chrestomanci series seems to follow a completely different set of rules: one plays out like Romeo and Juliet if the Capulets and Montagues happened to be families of gifted, temperamental magicians, while another follows a criminal gang of interdimensional smugglers. Chrestomanci is a bureaucratic regulator who monitors a panoply of different worlds, each of which has its own unique magical properties; he is a scathing, sarcastic deus ex machina, called into every story just as everything seems to be falling to bits. He is an excuse, in other words, to bind a handful of completely distinct fantasy universes together—and in The Lives of Christopher Chant, in which we follow the future Chrestomanci himself as he hops between worlds, every new leap brings with it a brand-new kind of magic, the rules of which are foreign and cryptic and sometimes flat-out lied about.

Dark Lord of Derkholm is perhaps as close to an ideological novel as Jones ever wrote. Its entire universe, which is innately magical in a vague fantasyish sort of way, has been enslaved by Walt Disney Roland Chesney, a mean little man from our own world, who forces its inhabitants to stage dreary, small-minded "tours" for wealthy Floridans, all of whom are permitted to murder as many natives as they think would be fun. Emirs protest the racist caricatures they're told to playact of their own cultures, and enchantresses around the world complain about being dressed in skimpy clothes and promoted as seductresses; meanwhile, the world is strip-mined for its natural resources, ranging from gold and jewelry to magic itself. But this colonialist critique happens around the edges. Derkholm presents itself, instead, as the story of the weary man who's forced to run the show this year, and of his precocious, extraordinary children, most of whom aren't human. The family as a whole is capable of astonishing things, none of which are appreciated or even permitted; instead, they're all forced into various flavors of wage slavery (and literal slavery), and bent to the service of middle managers too small-minded to comprehend exactly what they're ignoring or destroying.

Year of the Griffin, a rare sequel to Derkholm, takes this political critique one step further, and depicts an education system destroyed by decades of cranking out an unimaginative capitalist labor force. It's a classic college hijinks story—frat house versus unamused dean—but the future of the world is at stake. The innate curiosity of students discovering a heretofore unknown world of potential is jeopardized by the banality of their classes and the petty grievances of their professors; the students might be foolhearty and immature, Jones suggests, but the condescension and contempt of their supervisors is far worse. Year of the Griffin is at once a farce and a nuanced coming-of-age story, and a depiction of a society that dishes out injustice, not with any calculation or intent, but for the sheer dumb reason that it's forgotten how to do anything else.

Time and again, these themes of power and oppression trickle their way into Jones' work. Archer's Goon is an urban fantasy about a family of demigods who collectively control their city, splitting up its various forces like a divine pantheon or an old-money dynasty. A Tale of Time City follows a rich family who'd rather destroy history itself than let themselves fall out of power. In Howl's Moving Castle, a wicked wizard and a wickeder witch each break hearts and destroy families for the sake of romantic convenience. And in Hexwood, one of the most disorienting fantasies ever written, an Arthurian fantasy serves as a pleasant facade for a tale about a brutal empire that abuses and tortures children to further its galactic reign.

But nowhere do Jones' ideas and themes come more clearly into focus than Fire and Hemlock, perhaps her masterpiece. Fire and Hemlock follows Polly Whittacker, age 19, as she desperately recalls the last nine years of her life, convinced that she's forgotten something terribly important: at some point, she thinks, she lost the one memory that made life meaningful, and she has a sinking feeling that she's running out of time to remember it. She's up against a family that's either magical or just tremendously wealthy—she's not sure which—and the book takes place across either a decade or one frantic night, depending on how you want to look at it.

The missing memory concerns both a childhood friend and a strange, older man, and a game of Let's Pretend that she and this man began to play. Bit by bit, over the years, the fantasy they invent seems to predict the world around them, until it's unclear whether their make-believe story was the real truth all along. This is interlaced with Polly's discovery of the arts—literature, music, dance, theatre, even pantomime—and with the fragmented little memories that, in retrospect, seem to define the years of her life, in the way that tiny moments and odd tidbits somehow become the bits we cherish most about our past.

There is something ineffable, Fire and Hemlock says, something not quite nameable, that separates the wondrous from the mundane. It's easy to think of it as a kind of fantasy, just as it's easy to think of it as a kind of artistry or a kind of love. Perhaps it's this: sometimes we share the world with other people, which is to say we create the world with them. We build moments together, however whimsical or serious, that only come to life because of the people we shared those moments with. And if we remember them fondly, it's because this is the essence of being human: to come together, in feeling and imagination and wonder, and to know that this, in the end, is what the world is made of. It's made of us. It's made of what we make of it, when we allow ourselves to make anything at all. Or, as Fire and Hemlock puts it:

When Jones lets herself mythologize evil, for once, it's as a kind of inevitability. Whether they're fey or not, the Leroy Perry family pushes the idea that this is how things must be, where "this" is a world in which the rich get richer, and the poor are either preyed upon or torn apart by the misfortunes of their own lives; "this" is a world where people are too preoccupied with their own miseries to care about anybody else, and where anybody's pleasure comes at the price of somebody else's suffering. "This" is the only life that Polly remembers, at first, where nothing—even her own engagement—means much of anything at all; "this" is the conviction that things couldn't possibly work any other way.

Against this impossibly ancient and powerful evil stand a cadre of unlikely heroes. Each one's gift—to the extent that they have a gift—is paltry; it's only worth what it's worth when it's combined with all the others. Most of these heroes first manifest as a struggling string quartet, and Fire and Hemlock is itself structured as a musical composition. The line blurs, between music and magic, music and life, life and magic, magic and love, love and life... and the more it blurs, the more each thread weaves with all the rest, the more it deepens. Magic is described, at one point, as something that you scarcely let yourself believe at first: it's a ridiculous whim, and then it's hardly conceivable, and then you tell yourself that it's impossible, until slowly, inevitably, you conclude that it couldn't possibly be anything but. This describes the joy of music too, Jones says, and the joy of reading, and the joy of meeting someone who you immediately know that you love, whether or not you realize that you know it. It's the scarcely believable joy of life itself, the magic that makes everything worth it, utterly implausible no matter how many times you encounter it.

After two and a half decades of reading Diana Wynne Jones, I'm still not sure whether this is a childishly simple view of the world or a profoundly complex one. At times, I think about all the unfathomable horrors of the world, and feel like a single passage of Jones somehow manages to lay them all bare; I then wonder whether I'm foolish to think that the world could really be so simple. But simple is not the same as straightforward—Jones taught me that too. What's simple about her worldview is that she takes for granted that the world is convoluted, confusing, and incredibly weird. Or, as one character in Fire and Hemlock succinctly puts it:

Strangeness versus straightforwardness. The embrace of all the wonders of the world versus the determination to force the world into a single form or shape. The dimwitted, monotonous banality of evil, set against the curious, imaginative good. And between the two a kind of magic, at once explaining the world and rendering it completely inexplicable, forging a reality that's impossible to comprehend until you stop expecting to comprehend it to begin with.

Of all the writers I've ever known, whomever their intended audience, Jones still describes the deepest magic of them all. She makes it look easy. Perhaps, when you see the world like her, it is.