Gaia Theory

[Chroma]

I'm looking to get a good book to explain Gaia Theory. It seems to be a strange way of looking at things, what I would almost see as backwards (putting the horse before the carriage with cause and effect). Does anyone have any good books that can fairly describe the idea? From what I can tell Lovelock's early work was pretty sloppy language-wise and hardly does justice to the idea as it is currently discussed.

Also what is everyone's opinion of it, is it just earth systems relabeled with a heavy focus on biological contributions? Does it deserve the term theory, or is it by all rights still a hypothesis? Or even worse non-scientific, as it is too hard to disprove? would appreciate some feedback, thanks.