There are these two young fish swimming along, and they happen to meet an older fish swimming the other way, who nods at them and says, “Morning, boys, how’s the water?” And the two young fish swim on for a bit, and then eventually one of them looks over at the other and goes, “What the hell is water?”

Joanna Macy, Mutual Causality in Buddhism and General Systems Theory: The Dharma of Living Systems (SUNY Press, 1991)
http://books.google.com/books/about/Mutual_Causality_in_Buddhism_and_General.html?id=APvFjc1VmW4C

Joanna Macy on systems theory/Buddhist philosophy/deep ecology (from her website, not this particular book):

“The greatest revolution of our time is in the way we see the world. The mechanistic paradigm underlying the Industrial Growth Society gives way to the realization that we belong to a living, self-organizing cosmos. General systems theory, emerging from the life sciences, brings fresh evidence to confirm ancient, indigenous teachings: the Earth is alive, mind is pervasive, all beings are our relations. This realization changes everything. It changes our perceptions of who we are and what we need, and how we can trustfully act together for a decent, noble future.”

http://www.joannamacy.net/livingsystems.html