J. K. Rowlingshe made a generation read

The idea arrived on a delayed train from Manchester to London in 1990 — a boy who does not know he is a wizard — and she had no working pen and was too shy to ask for one, so she sat and thought about it for four hours instead. The seven years that followed included her mother's death, a brief marriage abroad, a return to Britain as a single parent, and a manuscript typed out twice on a manual typewriter because she could not afford to photocopy it.

The chairman of Bloomsbury took the first chapters home. His eight-year-old daughter read them and came back asking for the next one. The advance was £1,500, the first print run five hundred copies, and an editor advised her to keep a day job on the grounds that nobody makes money writing children's books.

Seven novels later the series had done the thing publishing had decided was no longer possible: persuaded a generation of children to read long books voluntarily, in order, and then wait years for the next one. The later volumes are markedly darker and longer than the first, which is roughly what happens when you write a series while its readers grow up alongside it.

“It is our choices that show what we truly are, far more than our abilities.”

J. K. Rowling