The book has three parts ...
Aha! I read it so many years ago that I don't remember that. I was only 16, and it was the first serious book I'd ever read. I was captivated. I stayed up nights reading it, read it under the desk in class, read it at the dinner table (got in trouble). Despite the turgid prose, it was such a tremendous story, and developed such an intellectually fascinating philosophy, that I couldn't put it down.