I was surprised by how much I liked this book. It is a very brief survey of problems involving the concept of "self" or "person." Castell argues plausibly enough that we are only able to understand human action as purposive and not merely as mechanical. Then he argues more interestingly that the classical notion of the agent as something apart from human activity is necessary to explain human action. Since I am myself very attracted by Hume's deflation of the idea of self, this was food for thought. I don't find that Castell argues against deflationary accounts of self as sophisticated as Hume wants to give, but even so, this reading stimulated me to think about what an account of the self has to account for. The writing is very readable and not at all technical.