J.K. Rowling, author of the beloved Harry Potter series, created the best-selling book series of all time. But her success was not an inevitability. Rowling was an unemployed single mother on public assistance when she wrote the first book, but with a little inspiration from some unlikely places, she took the literary world by storm.

Rowling owes her success to an 8-year-old girl

Like many first-time authors, Rowling struggled to get her first book, Harry Potter and the Philosopher’s Stone published. (The name was changed to Harry Potter and the Sorcerer’s Stone in the United States.) The book was rejected by over a dozen publishers. Finally, a small British publisher, Bloomsbury, said yes. Bloomsbury saw the potential of the book because the chairman of the publishing house gave the first chapter to his then 8-year-old daughter, Alice, to read. Upon finishing, she immediately demanded the rest of the book. However, Bloomsbury was not convinced that it had a bestseller on its hands. Rowling’s editor, Barry Cunningham, warned her that she needed to get a day job because it was impossible to make a living writing children’s books.

Rowling made up her middle initial in response to her publisher’s sexism

In addition to assuming that the book would not sell well, the editorial team at Bloomsbury advised Rowling that she should not publish under her real name, Joanne Rowling, because boys would not read a book written by a woman. That sexist assumption certainly did not give much credit to boys, and took it for granted that girls would read a book written by men. Rowling, eager for success, agreed to write under the name J.K. Rowling. The J was her first initial. But Rowling does not have a middle name, so she used K as a tribute to her grandmother, Kathleen.

The names of the houses at Hogwarts were originally written on a barf bag

Rowling likes to write her first drafts in longhand, preferably in black ink. Sometimes she found herself inspired, but short on paper. So she wrote on anything she could find. She told Amazon UK that she used a truly novel paper substitute when she was concocting the name of the Hogwarts houses: “The names of the Hogwarts Houses were created on the back of an aeroplane sick bag. Yes, it was empty.”

The increasingly dark tone of the series was inspired by Rowling’s life experiences

The Harry Potter series becomes considerably more sophisticated as it progresses, grappling with serious issues like death and bigotry. Rowling has been open about the fact that much of the darkness is autobiographical. She told Oprah Winfrey that, though she did not realize it when she began writing the series, making Harry an orphan, along with his subsequent experiences with death, was her way of dealing with the death of her mother, who died of multiple sclerosis when Rowling was 20: “If she hadn't died, I don't think it's too strong to say that there wouldn't be Harry Potter. The books are what they are because she died.”

The Dementors, among the most frightening creatures in the franchise, were inspired by her struggles with depression during her 20s: “It's so difficult to describe to someone who's never been there because it's not sadness. I know sadness. Sadness is to cry and to feel. But it's that cold absence of feeling — that really hollowed-out feeling. That's what Dementors are."

Quidditch was based on basketball

Quidditch, the sport of choice at Hogwarts, resembles flying lacrosse in the Harry Potter films. One might imagine that the British Rowling thought of cricket when creating the game. After all, the Quidditch brooms look a little bit like bats. Actually, her inspiration was the all-American basketball. In her Amazon interview, Rowling explained, “I wanted a sport for wizards, and I'd always wanted to see a game where there was more than one ball in play at the same time. The idea just amused me. The Muggle sport it most resembles is basketball, which is probably the sport I enjoy watching most.”

Thanks to the popularity of the books, Quidditch has become an actual sport, with teams at many universities and its own world cup tournament. Rowling approves since she put a lot of effort into making it a fully realized sport: “I had a lot of fun making up the rules and I've still got the notebook I did it in, complete with diagrams, and all the names for the balls I tried before I settled on Snitch, Bludgers and Quaffle.”