That was VERY interesting to read, yet, at the same time, also pretty dry. I have read several other books while reading this one to make up for this.
So, what is it about? A non-essentialist view on how professions develop. This means that it does not ask “what is a profession?” but rather: “How did particular professions change in the past?”, with a focus on their interactions with other professions (thus the System in the title). The book has nice explainations for a lot of things that one might wonder about: Why is university training so different than how people work in the profession? Why are universities important for professions? Why do some professions have a clear grasp on field they have no real solutions for? What are alternatives to professions?
Its rather Foucaudian, i.e. there are power struggles everywhere and they are intertwine with state, law and knowledge (The process/event ideas and its non-essentialism are Whitehead and Dewey-ish, though). With its focus on history, what is missing is the detailed study of how professional claims are made at the workplace on a small scale, but thats something I point out because of my personal interestes rather than as a lack of the book itself.