Gaia's Garden presents ideas for creating a garden space that looks, feels and behaves as if it happened naturally, instead of being planned and groomed by civilized folk. This doesn't mean it looks unkempt, but that each plant within a garden group exists in a relationship with others in a mini ecosystem. This type of planting produces healthier plants and greater yeilds while preserving or improving the health of the soil and reducing the amount of work it takes to maintain established beds. (Though the amount of work it takes to establish them in the first place is not reduced by any means.)
Although I think that the book could have been simpler in its execution (although it promises it won't read like a text book it does in some places) and it digressed a little too often for me (examples are nice, but I got tired of them) I was very pleased with it. It was both informative and inspiring.