The book that rocked my world? That is so very hard to choose: The Martian Chronicles by Ray Bradbury or Stranger in a Strange Land by Robert Heinlein.
One reimagines an ancient race of Martians and their response to a human invasion. Their genocide from a human carried disease leaves ghosts and terrors that walk the planet. The book is tiny... but full of horrors. And is also a call to arms about the way invader and occupied frame each other.
Bradbury taught me about perspectives, about the world unseen, about hatred that reaches over the years, over generations.
Heinlan though of Mars as well, but as a failed experiment. An abandoned attempt at colonization, humanity packed up and left. Accidentally leaving one child behind. That human was raised by martians, rocklike giants that spoke slower than water. And years later, when he was discovered, humans "rescued" him, bringing him back to earth, a stranger. And the way he viewed the familiar world, the way he saw through corruption and need, hope and anger... transformed the book from a science fiction work to a messianic one.
Devastating. And to this day, you will see people use the word "Grok" to mean Love, eat, imbibe, accept, understand, become one, join, etc... It has no translation outside of that novel. But that word is just about everything. And it was an idea created by one imagination, transforming readers.
That is what I hope to do one day: change the world for my readers, one idea at a time. So, I started with ordinary magic, the hidden powers held in secrecy right in front of our eyes: the magic of houseflies. Because they are everywhere, known to everyone, and because they are non harmful and yet annoying. What if I could write a world that changed everything?