This is a book about the natural history of human nature. It is not a book about philosophy for philosophers. It is a plain and straightforward statement for ordinary people of what another very ordinary sort of man who has considerable experience with the mechanisms of human life and how they work thinks about it all. We all want to understand human nature better, because it is our nature. The better we understand it the more likely we are to get along with ourselves, our neighbors, and our surroundings in general. We want to make life more worth while, to get as much out of it as we can and to put as much into it as we can, to make a better living and to have as much fun doing it as possible. We need to know how we live, what the apparatus of life is and how it works, in order to make a better job of it. -- Preface.