Admittedly, I haven't yet read this book cover-to-cover and don't even own my own copy, as I was merely borrowing the copy from the MSRI library during a brief visit there. But wow, what a book! This work strikes a great balance between speculation and formalization, and shines a light on perspectives on self-reference in philosophy, computer science, linguistics, and other areas. It's surprisingly accessible for the level of rigor it achieves, and while some familiarity with set-theory is a helpful pre-requisite, I imagine that non-mathematicians might also be able to enjoy this book with a bit of patience and some willingness to cross-reference unfamiliar topics.