The Secret Commonwealth (The Book of Dust, #2)

by Philip Pullman

The Hyperchorasmians, by a German philosopher called Gottfried Brande, was a novel that was having an extraordinary vogue among clever young people all over Europe and beyond. It was a publishing phenomenon: nine hundred pages long, with an unpronounceable title (at least until Lyra had learned to pronounce the ch as a k), an uncompromising sternness of style, and nothing that could remotely pass for a love interest, it had sold in the millions and influenced the thinking of an entire generation. It told the story of a young man who set out to kill God, and succeeded. But the unusual thing about it, the quality that had set it apart from anything else Lyra had ever read, was that in the world Brande described, human beings had no dæmons. They were totally alone.

Reminds me a little about the man in the high castle. A book within a book where reality is completely different