If I ever do a fourth edition, I might set myself a rule not to expand it any longer.
There's very little that I cut — occasionally I would read a sentence I didn't like. It's rare for me to remove somebody from the history of the music. Mostly, I'm trying to expand my coverage rather than narrow it. That said, if the book becomes too bulky, it's no longer readable. If I ever do a fourth edition, I might set myself a rule not to expand it any longer. I don't want this to be a reference book that people just put on the shelf, I want them to be able to read it from cover to cover.