From Scott Rao:

"When I began in the coffee business in 1993, I had read every book I could find about coffee.  After reading all of those books, however, I felt as if I hadn't learned much about how to make great coffee.  My coffee library was chock-full of colorful descriptions of brewing styles, growing regions, and recipes, with a few almost-unreadable scientific books mixed in.  I would have traded in all of those books for one serious, practical book with relevant instruction about making great coffee in a café.  After being in the coffee business for 15 years, I decided someone needed to write that book, so I wrote The Professional Barista’s Handbook."