A book can't hide it's source code, it can't hide it's contentes. It can't crash like a computer program, so it is kinda free. A book is much more free than a proprietary computer program, since you have the "source code" for the book. And people can sell free software, but not get very much money from each copy, so selling books about the software is IMHO a good way of making money.
Free software vs. Free books (Score:1)
A book can't hide it's source code, it can't hide it's contentes. It can't crash like a computer program, so it is kinda free. A book is much more free than a proprietary computer program, since you have the "source code" for the book. And people can sell free software, but not get very much money from each copy, so selling books about the software is IMHO a good way of making money.