Peck's attack on simplistic thinking in this book is refreshing. There are subtle hints that we are innately lazy, which coincides with Mark Twain's more light-hearted view of mankind (and my own). There are also subtle (i.e. not stated) references to the theory of Yin-Yang in this book... although he doesn't come right out and say it, a good portion of this book is about balance. I don't like the constant references to his other works, but self promotion is a minor flaw. A few passages in this book are so insightful that they should be required reading for young adults... and all of us old dogs, too!