"War and Peace"
When I was a kid, was going through a box of old books that my elders left and found this one. And trust me, with no internet, no TV and no nothing, I had to go through this one to pass time.
Assumed it should be fun reading stories about war right? Only to find it's full of all philosophical discussions and almost no description of war. That was surprising : why talk so much meta talks on war, instead of the actual events on that war?
Later in life, found out that this book is infamous for being too long, even the name of the book is used as a phrase for boring writing.
But you will find philosophical gems in there, no denial there. Though not much on war.