Stories can change the world. According to the British Library, child labor laws were passed just six months after the publication of Charles Dickens’ A Christmas Carol, and Victor Hugo hoped that Les Misérables would “inspire people to work toward a truly equal society,” according to the State Library Victoria.

In honor of the fact that books can change us for the better—and in honor of National Book Lovers Day—here’s what brought five of the most successful books to shelves.

“Harry Potter” by JK Rowling

The inspiration for “Harry Potter” came to JK Rowling while she was on the train from Manchester to London.

“I was sitting there staring out the window and the idea just came out of nowhere. It was the purest brainwave I’ve ever had in my life and I’ve been writing about it ever since,” Rowling told ITN a year after the first Harry Potter book was published.

For Rowling, at the beginning of her novel, “Harry was the only idea.”

Her initial ideas for the character revolved around him being an unusual boy “who made very strange things happen for eleven years,” Rowling said.

She continued: “There was clearly a secret about him, but he didn’t know what it was. And then he got the letter telling him he’d got a place at wizarding school, and I just thought it would be a lot of fun to write about it.”

In a later interview with Medium in 2023, Rowling explained how she got inspiration for other aspects of the book.

In particular, Hagrid, the half-giant who lives on the Hogwarts grounds, “was inspired by a biker Rowling met in the west of England,” and Harry’s closest friends, Hermione and Ron, were inspired by their own friends from college.

“A Christmas Carol” by Charles Dickens

The story of Scrooge, Tiny Tim and the visits of instructive ghosts in the middle of the night is a staple of the Christmas season, but Dickens’ novella was initially less about the holidays and more about dealing with poverty.

England was suffering from economic problems in the mid-19th century, and many historians have called the decade in which Dickens wrote A Christmas Carol the Hungry Forties.

In several earlier publications, Dickens had begun to incorporate social and economic themes into his plots, according to an article titled “Children in Dickens’ Novels” published in Arc Journals. Dickens was “himself a victim of child labor.”

An 1842 report on child labour in Britain reflected the climate of the time. It listed the working conditions that prevailed in coal mines in various locations across Britain and found that children began working in the mines at a very young age.

One worker explained to the men conducting the study: “Fathers carry their children downstairs when they are four or five years old.”

Another said: “Children are taken down as soon as they can crawl.”

Dickens originally intended to publish a pamphlet under his own name entitled An Appeal to the English People on Behalf of the Poor Man’s Child, but instead he decided to do something that, according to Penguin Books, was “twenty thousand times more powerful.”

Thus, A Christmas Carol was born. In an effort to bring about change, Scrooge becomes a good person, Bob Cratchet gets a raise, and Tiny Tim is saved from starvation.

Historians also attribute the waves that “A Christmas Carol” made to the Factory Act of 1844, which came into force soon after. The law limited the number of hours that children were allowed to work and made school a part of the working day.

“The Hunger Games” by Suzanne Collins

Collins got the inspiration for “The Hunger Games” one evening while watching television.

In a 2008 interview with the School Library Journal, Collins explained, “One night I was lying in bed flipping between reality TV shows and real war reports. On one channel there’s a group of young people competing for… and on the next channel there’s a group of young people fighting in a real war.”

“I was really tired and the lines between these stories started to blur in a very disturbing way,” she continued. “That’s when Katniss’ story came to mind.”

At the time, Collins was finishing the final book in another series, and she “knew she wanted to continue writing about just war theory for a young audience,” according to a later interview with fellow author David Levithan in 2018.

Collins defined just war theory in the interview as “an attempt to define under what circumstances one has the moral right to wage war and what behavior is acceptable during that war and in its aftermath.”

“Atlas Throws Off the World” by Ayn Rand

Ayn Rand left Russia in 1925 to study film in California. She was disillusioned with the Soviet Union’s philosophy, which led her to write Atlas Throws the World Away. The book is about highly successful innovators and leaders who left society when the government became too oppressive.

The Objective Standard reported that Rand got the inspiration for her biggest hit during a 1943 telephone conversation with her friend Isabel Paterson, a columnist for the New York Herald-Tribune.

Paterson told Rand she had a “duty” to explain her philosophy in a nonfiction book. Some, including The Objective Standard, believe the conversation was about a book Rand was writing, The Moral Basis of Individualism, which was never completed.

Soon after that phone call, Rand began writing a novel called Atlas Throws Off the World, which would set out her own moral philosophy.

In a 1959 interview with journalist Mike Wallace, Rand explained the philosophy on which Atlas Throws Off the World was based. “My morality is based on human life as a standard of value. And since man’s reason is his basic means of survival, I believe that if man is to live on earth and live as a human being, he must regard reason as absolute,” she said.

“His highest moral aim is the attainment of his own happiness,” she continued. “And he must neither compel other men nor accept their right to compel him. Each man must live as an end in himself and follow his own rational self-interest.”

“Les Miserables” by Victor Hugo

The brutal poverty in 19th century France inspired Hugo to write “Les Misérables”.

However, in David Bellos’ book The Extraordinary Adventure of Les Misérables, he explains that Hugo actually witnessed a man being taken away by the police for stealing a loaf of bread.

NPR added: “He wore mud-splattered clothes, his bare feet were in wooden clogs, and his ankles were wrapped in bloody rags instead of stockings.”

In his foreword to “Les Misérables,” Hugo writes: “In my eyes, man was no longer a man, but the specter of misery, of poverty.”

This moment changed the plot of Hugo’s novel, which until then had revolved around Fantine.

Stanford University also reported that three decades before he began writing Les Misérables, Hugo was involved in a violent mob following the death of General Jean Maximilien Lamarque.

“Hugo was surrounded by barricades and threw himself against a wall, as all the shops and stores had been closed for some time. He found shelter between some pillars. For a quarter of an hour bullets flew in both directions,” the article said.

Stanford suspects that this moment helped Hugo describe the barricades in Les Misérables with extreme precision.