Lovelock

The title?  Gaia: A New Look at Life on Earth by James Lovelock.  This is the original Gaia Theory.  The real deal has less to do with the spirit than with the natural biological rhythm of Earth, in light of the idea that the world's homeostasis certainly acts as any given living organism.

Lovelock also wrote The Ages of Gaia : A Biography of Our Living Earth.

I hate to admit that I've not read through either of them.  However, it is on my list.