As personal/subjective MYTH, "Gaia" denotes the archetypal awareness of all indigenous cultures, including those of all our ancestors, that they belong to the land, rather than vice versa; that, as Shakespeare says, "the Earth that's Nature's mother is her tomb; What is her burying grave, that is her womb..." It also can refer, therefore, to the intuitive sense of communion, of the sacred, that most people who are honest with themselves will admit that they feel in the midst of beautiful natural settings - something celebrated by poets the world over, from time immemorial.
GAIA: The Model
As objective MODEL, Gaia refers to the Lovelock/Margulis theory of life on Earth as a self-organizing, sun energized system. In the few eons since life began, Gaia has reached a state of relative stability with an average atmospheric temperature of 20C and an oxygen level of 21%. This atmospheric cocktail is the result of, and wholly dependent on, a vast network of living biodiversity.
Gaia is a model which already has proven its worth in generating important new questions for research into the codetermination of life and its environment--and of course, a model with far-reaching policy, ethics and values implications arising from its core conception of nature as an integrated system rather than a random "resource" available for plunder.
GAIA: The Metaphor
Metaphorically, "Gaia" represents the notion of inherent web-like interconnectedness - everything effects everything else. It relates to the emerging episteme wherein Humanity is viewed as inherently part of the Ecosphere - a self-regulating, living system, not a "resource" that we can be exploited with impunity. This awareness of Humanity's embeddedness within Gaia increasingly goes under the name of "Gaian consciousness."
GAIA: The Movement
Growing numbers of us, locally and globally, as environmentalists, policy analysts, teachers, and concerned citizens of the planet, are trying to awaken humanity from the delusions that human sustainability could emerging from continued industrial growth - from TV consumerism and addiction to money and power. The Gaia Movement includes the many organizations concerned with human population such as: Optimum Population Trust (Europe), Negative Population Growth Inc. (USA) or Global Population Concerns (Canada).
The Gaia movement seeks, quite simply, to save us from ourselves by expanding our identification -- our sense of "self" -- beyond community and nation-state, beyond even humanity -- to the whole biosphere -- to Gaia. This movement can/must lead to a new relationship between politics and governance, Humanity and the environment.