I could easily talk in-dept about every chapter of this book. Each and every one is worthy of a prolonged discussion, discussion involving theologists, historians, sociologists, psychologists... (pardon my english).
It will reveal how big of a donkey each one of us is, but it'll do it in a poetic manner. One concept that I found very interesting is something that could be translated as "mind mirror". Imagine a mirror standing in front of you and showing your deepest thoughts - good and bad ones. From thinking about nature and its beauties, to murdering your friend. Now imagine if others, lets say that same friend could also see the mirror. Saint Nicholas suggests we try to imagine that mirror every night before sleep, in order to clean up garden of our soul.
Other interesting ideas are being pesimistic because certain politicians are not making our life better, as if several people could actually make our lives better. Society gets better by its individuals being better and making new generations better than they currently are.
I'm making all of this sound too simple, retriving it all from depts of my memory. All in all - great book that talks about wide range of topics in a deep way. If you are a Christian you'll appreciate it even more.