Lost in Thought is a book with four overlapping layers of content: (1) It's a book about thought, thinking, and letting thinking go. (2) It's a book about ideas for books the author (Koren) conceived of, tried to develop, and then discarded. (3) It's a modern-day enlightenment story--a quirky Siddhartha--that involves an avocado sandwich. (4) And it's a book about making a book, and the qualities of paper used to make it.