Rowling uses numerous devices to make her book a credible representation of an actual book from the Hogwarts' library.

First and foremost, she does not identify herself as the author, but rather she creates a fictional character who anyone immersed in the magic world of Harry Potter can believe had the proper credentials to write the book. Then she embellishes her story with other colorful characters who, like Whisp, add to the suspension of disbelief.

The creation of a network of secret societies also adds to the suspension of disbelief.

Rowling mentions the regulations on the game of Quidditch imposed by the Department of Magical Games and Sports, for instance. She explains that this department developed as a result of the International Statute of Wizarding Secrecy of 1692, which made every Ministry of Magic "directly responsible for the consequences of magical sports played within their territories."

Furthermore...