Every fan of Batman knows Arkham Asylum, the madhouse for Gotham City’s criminally insane. When the Dark Knight manages to foil a plan and capture a criminals, he takes them there to move onto the next. What fans may not know is Grant Morrison’s classic story Arkham Asylum: A Serious House on Serious Earth. Widely viewed as the definitive Arkham story, it’s also one that deconstructs not only Batman’s rogues, but Batman himself. Asking the question: does Batman belong in the madhouse as well?

The join effort from Grant Morrison and artist Dave McKean marked the writer’s first dive into the Batman mythologoy, propelling him to popularity becoming a regular Batman writer in the years to come. The book remains one of the best selling graphic novels of all time in America, considered one of the great Batman tales, alongside stories like the The Killing Joke or The Dark Knight Returns. And such special honor should be expected, considering the premise… when the criminals break out and take control of the asylum, forcing Batman to head into a home for the mad, seeking to find order instead of chaos.

Arkham Asylum’s positive reception has largely to do with the fact that Morrison reveals more about Arkham and its residents than was ever attempted prior, introducing new layers of depth and symbolism between Batman and his foes. As Batman travels through Arkham, he comes into contact with several of his iconic enemies in ways he never thought he would, challenging him with the suggestion that he might have more in common with his foes that one would think.

The suggestion starts even earlier at the novel’s outset, before Batman even goes to Arkham. Where other writers keep Batman on a strictly black and white scale of morality and sanity, Morrison’s admits to Commissioner Gordon that he’s afraid. That sometimes he questions himself and the rationality of his actions. A man dressed as a bat who beats up criminals? It doesn’t seem all that far away from a man dressed as a clown who commits crimes. Batman admits he’s worried that when he walks through the gates of Arkham, it will feel like coming home. And as if he belongs there as much as any other Arkham resident

But what makes it even more interesting, and what begins the layering of ideas that makes Morrison and McKean’s work so acclaimed, is the hero’s confession to Gordon that it isn’t Batman who’s afraid… it’s Bruce, the man using Batman as a symbol to protect himself. Bruce has Batman, Two-Face was once Harvey Dent, Scarecrow was once Dr. Jonathan Crane, and so on, and so on. The commonality certainly seems like it would be a frightening thought for the Dark Knight. Or it arguably should be.

Morrison’s symbolism goes even further, taking this questioning, uncertainty, and fear, and applying it to show how diametrically opposed Batman is with the Joker. While Joker is an agent of chaos, Batman is one of control and order. Even so, the idea of Batman himself is a diametric symbol, meaning different things to whoever’s in contact with him. To his foes, Batman serves as a symbol for fear and intimidation. To those he protects, he’s a symbol for hope. And that distinction ultimately makes all the difference, from an academic and heroic perspective. Sure, the rationality of dressing up as a bat could put Bruce in the category of the ‘mentally troubled.’ But it’s the symbol that alter ego represents, and what Bruce chooses to do with it that sets him apart. In other words, the good that the Batman stands for as a symbol.

Batman fans know that there’s not much that can shake or scare the Dark Knight. Arkham Asylum is a truly dark and disturbing place, meant for the worst of the worst. It’s no surprise that it could cause Bruce Wayne to question his crusade or motives. While Morrison’s Arkham Asylum does explore the commonalities of symbolism in the Batman mythos and those of the villains he fights, like many other creators before and since, he concludes by showing the symbols that separate Batman as the hero and protector that Gotham needs. In Arkham, and without.

More: Batman: Arkham Asylum Explains Why The Movie Has So Many Villains