The very last chapter of the novel is called "The Marriage of Quasimodo," and the very last image of the book is the skeletons of Quasimodo and Esmeralda (conveniently still in her white dress) locked in an embrace. The ugly and the beautiful, together at last. What a happy ending, right?
Okay, not really.
For those of you who are wondering, the message is not "beauty is on the inside." Remember, Esmeralda never gets over her aversion to Quasimodo; to the very end, she's all about the svelte physique of Phœbus. After all, this is a novel about appearances and how they matter, like, a lot (check out our "Themes" section for more). Quasimodo, frankly, doesn't have a chance.
But it's no coincidence that the final image is of the ugliest character next to the most beautiful character. The fact is, the only way Quasimodo and Esmeralda could ever be together is in death, when appearances cease to matter. Pretty morbid, huh?
But the end of the book actually goes beyond appearances. Let's look at another big theme here: the idea of temporality. Remember how Book V.II was all about how the printing press will kill the cathedral because printed books can endure through history better than even a building can? While you're at it, take a look this passage from the Author's Preface:
The man who wrote this word on the wall disappeared man centuries ago, the word in its turn has disappeared from the wall of the church, the church itself will perhaps soon disappear from the face of the earth.
The widely printed novel may be more permanent than a stone edifice, but both are more permanent than the human body. You see, human histories are pretty frail objects. Once a person dies, all that might remain of his or her life are some graffiti they once etched onto a cathedral wall. But the novel itself is like a cathedral: it makes an individual's story permanent. Quasimodo's skeleton might fall to dust, but his novel survives. It's his cathedral.