New textbooks on various aspects of theoretical physics seem to overflow the market. A prospective author must be able to provide convincing answers to at least the following questions (posed by the publisher, colleagues, and last but not least, by him/herself and the associated family members). (i) Why bother writing the book? (ii) Is there a sufficient audience for the text? (iii) Isn't the topic already covered by a number of books, and isn't the author's best hope just to add a new wrinkle to the existing lore (and perhaps enhance his/her own publication record)? (iv) Is there any practical need for the book? (v) Are there any important open problems that the book will contribute to finding solutions to (or, at least, be able to identify points where the present understanding is insufficient).