Frodo says the line, quoting Bilbo, on the road to Crickhollow, near the very beginning: “It’s a dangerous business, Frodo, going out your door. You step onto the road, and if you don’t keep your feet, there’s no knowing where you might be swept off to.” It is one of those lines Tolkien drops almost in passing, without emphasis, tucked into a conversation among hobbits walking through the Shire, and yet it contains the entire thesis of his work.

Going out your door is dangerous. Not going out is worse.

Hobbits are the most domestic creatures in Middle-earth. They eat six meals a day. They smoke pipes in the garden. They have no interest in adventures, consider them a nuisance, an inconvenience, the sort of thing that makes you late for dinner. Their ideal life is a comfortable house with a well-stocked pantry and no surprises. Tolkien describes them with obvious affection, because Tolkien was, in many ways, a hobbit himself: a man of fixed habits who loved his garden, his pipe, his beer, his academic routine at Oxford, and who looked at the modern world with a mixture of distrust and sadness.

But Tolkien, who was a hobbit, wrote books about hobbits who leave home. That is the fundamental tension. He didn’t write about elves seeking adventure, which would have been easy, because elves are immortal and curious and have nothing to lose. He wrote about hobbits, about creatures for whom adventure is the least natural thing in the world, the most costly, the most contrary to everything they are. And precisely for that reason, the most necessary.

Bilbo doesn’t want to go with the dwarves. The first chapter of The Hobbit is the story of a man trying with all his might not to be dragged into an adventure. Gandalf shows up, the dwarves invade his house, eat all his food, sing him a song about a faraway mountain, and Bilbo says no, he’s not interested in this sort of thing, he is a respectable Baggins. And the next morning he runs after them without so much as a handkerchief. Why? Tolkien gives no clear psychological reason. He says something woke up in Bilbo, something Tookish, something from the adventurous branch of his family, and that this something was stronger than comfort.

It is tempting to read this as a narrative trope: the reluctant hero who answers the call. Campbell systematised it, Hollywood turned it into formula. But in Tolkien it is something else. In Tolkien, adventure is not a dramatic arc. It is a spiritual necessity. Bilbo doesn’t leave home to become a hero. He leaves because staying would be a form of death, a comfortable, warm, well-fed death, but death all the same. The Shire without adventure is a paradise that becomes a prison. Tolkien shows this at the end of The Lord of the Rings, when the hobbits return and discover the Shire has been taken over by Saruman: the safe place ceased to be safe because absolute safety does not exist, and those who believed they could ignore the outside world found that the outside world did not ignore them.

Frodo repeats Bilbo’s pattern but in a darker key. Bilbo goes on an adventure and comes back richer and wiser, with a magic ring in his pocket and good stories to tell. Frodo goes and doesn’t really come back. He returns to the Shire, yes, but he can no longer live there. He is broken. The Ring damaged him in ways that don’t heal, and in the end he sails from the Grey Havens with the elves, westward, towards something that is not exactly death but is not life as he knew it either. The adventure cost him everything. And Tolkien, who was not naïve, does not pretend the cost is less than it is. There is no proportional reward. There is no happy ending in the conventional sense. There is a man who did what had to be done and paid the price.

This is what separates Tolkien from the generic fantasy that came after him. In generic fantasy, adventure is desirable. It is fun, exciting, it comes with rewards. The hero goes out, fights, wins, returns in glory. In Tolkien, adventure is necessary but not desirable. It is something that breaks you. That changes you in ways you did not choose. That takes you away from the things you loved and doesn’t let you fully return. Sam can go back to the Shire and plant his garden and raise his children. Frodo cannot. Adventure affects each person differently, and some it affects in ways that have no remedy.

There is something profoundly Catholic in this vision, and I don’t think you can understand Tolkien without understanding it. In Catholicism, vocation is not a career choice. It is a calling. Something that comes from outside, that asks of you what you don’t want to give, that pulls you from your comfort and sets you on a path you didn’t design. The correct response to a calling is not enthusiasm but obedience, and obedience carries a cost no one can anticipate for you. The saints were not people who had a good time. They were people who said yes to something that destroyed them and rebuilt them as something else. Frodo is a secular version of that: someone who said yes and was destroyed and rebuilt, and the rebuilt version no longer fits in the world where he used to live.

In a world like ours, which optimises comfort with an efficiency unprecedented in human history, the idea that comfort is insufficient sounds almost offensive. We have food delivered to our doors, infinite entertainment, climate control, minimised risk. We can live entire lives without ever leaving our particular Shire. And yet something fails. Depression and anxiety rates in the developed world are the highest in recorded history. People have everything they need and feel empty. They medicate, distract, anaesthetise, and the emptiness persists.

Tolkien diagnosed this in 1937, before smartphones, before the internet, before industrial comfort reached its present form. He diagnosed it because he was a medievalist who knew a world where comfort did not exist and where life had an intensity that modernity sacrificed on the altar of safety. He did not idealise the Middle Ages, he was not a naïve reactionary who wanted to return to plagues and serfdom. But he understood that something was lost in the transaction, something to do with risk, with exposure to the unknown, with the real possibility of failing, of suffering, of not coming back.

Adventure, for Tolkien, is not tourism. It is not a gap year. It is not skydiving or backpacking through Southeast Asia. Adventure is the willingness to be transformed by something you do not control. It is saying yes to a road whose end you cannot see. It is stepping out your door knowing that what lies on the other side may destroy you, and stepping out anyway, not out of bravery but out of the intuition that staying would destroy you in a worse way: slowly, silently, through the accumulation of identical days.

“It’s a dangerous business, going out your door.” Yes. And not going out is the most dangerous business of all.