A few chapters in the book I knew nothing about before writing them (Heroku, pieces of others) and the review process also pointed out a few places where my knowledge was actually wrong. As a whole, it's been a huge learning process, and that's pretty much been the best part.

So how did you get to the point of writing a book on topics you didn't know about? I always thought the process was more like "well, I know this shit backwards in my sleep, I should write a book!"

It was more like having 50% of the book already known, and knowing that the book wouldn't be great without another 50% on top of it.

How did you find a subject that you felt you knew 50% about? :-) Given how much I've learned from other people, and the web, I have difficulty feeling like an _authority_ on any technical subject.

I think beginner books are easier to get to that 50%. The subject I'm teaching really isn't that hard, it just needs to be explained differently.

So, that said - maybe it's not feeling like an authority, but more feeling like you have an alternate/interesting/different take on a subject.