Book six was all about Zosima. It tells us childhood stories and facts about Zosima so we understand why he became a monk and whatnot. The man who confessed to Zosima that he was a murderer was completely insane. No normal person could hold in a secret like that. I like Zosima's views on religion. I find them intriguing. Zosima is a really cool monk. I'd hang out with him. :]