In a Guardian piece, Stephen King recalls how two disparate thoughts crashed together in his head, allowing him to create his first novel, Carrie, 40 years ago. The opening:

“While he was going to college my brother Dave worked summers as a janitor at Brunswick High. For part of one summer I worked there, too. One day I was supposed to scrub the rust-stains off the walls in the girls’ shower. I noticed that the showers, unlike those in the boys’ locker room, had chrome U-rings with pink plastic curtains attached.

This memory came back to me one day while I was working in the laundry, and I started seeing the opening scene of a story: girls showering in a locker room where there were no U-rings, pink plastic curtains or privacy. And this one girl starts to have her period. Only she doesn’t know what it is, and the other girls – grossed out, horrified, amused – start pelting her with sanitary napkins … The girl begins to scream. All that blood!

I’d read an article in Life magazine some years before, suggesting that at least some reported poltergeist activity might actually be telekinetic phenomena – telekinesis being the ability to move objects just by thinking about them. There was some evidence to suggest that young people might have such powers, the article said, especially girls in early adolescence, right around the time of their first —

POW! Two unrelated ideas, adolescent cruelty and telekinesis, came together, and I had an idea …”