From the reviews: "The articles present recent research on conceptual and mathematical issues aiming at a unified framework for quantum field theory and general relativity. ... In my experience, this is the best single text to use to learn field theory that one can buy today. ... for a solid grounding in the fundamentals of field theory there is no better place to start then this." (Philosophy, Religion and Science Book Reviews, bookinspections.wordpress.com, March, 2014)