"Anathem" by Neal Stephenson
It was a long, windy book with so many philosophical concepts that make you go "hmmm" that I don't have the candor to review it properly. It is relatively long, yet I don't see how it could be smaller. I'm afraid of even thinking about how long the manuscript was before the author started shortening it with the editors.
Overall, it's a fictional universe going parallel to ours (in more than one way) where all the smart people were round up to monastic way of life and the rest of the humanity kept living as is, resulting in a bit of an idiocracy type of a scenario.
Neal touched upon many concepts like perception vs reality, stagnation of new knowledge creation (probably my favorite part of the books was the Lorites whose whole job was to point out existing scholarly works to whoever thought they came up with something new).
Unfortunately, the main crisis of the book is very anticlimactic akin to the main crisis of The Three Body Problem. Nothing epic, but something roughly plausible. Stephenson wrote another one of his roadtrip-like novels that resolves in one of the side characters having supernatural abilities (seriously, that jump from everybody's dead to the main character waking up in a hospital is like the nukes from the Herbert's Dune).
Overall, I'd recommend reading this book. At least this time Neal didn't write underage sex into it!