And Boyd almost didn't write it. Robert Coram (the author of the aforementioned biography) summarizes the unconventional manner in which the manual was written (on page 104 of my edition):
Boyd could not write the manual and continue flying and teaching; there simply wasn't enough time. Plus, the idea of sitting down at a desk and spending hundreds of hours writing a long document brought him to the edge of panic. He was a talker, not a writer. When he talked his ideas tumbled back and forth and he fed off the class and distilled his thoughts to the essence. But writing meant precision. And once on paper, the ideas could not be changed. ...It's a subject I didn't really cover much in my last post: the method of communication can impact the actual message. The way we communicate changes the way we think. Would Boyd's work have been as great if he didn't dictate it? Maybe, but it probably wouldn't have been the same.
Spradling came up with the solution. "John, don't make this a big thing. We have some good Dictaphones. Why don't you just dictate the damn thing?"
Incidentally, I don't normally go in for biographies, but this is an excellent book so far. Part of that may be that Boyd is a genuinely interesting guy and that he was working on stuff that interests me, but I'm still quite enjoying myself.