It is useful to think of sustainability in the metaphor of an athletic game: It is possible to “lose”–that is, to become unsustainable, as happened to the Western Roman Empire. But the converse does not hold. Because we continually confront challenges, there is no point at which a society has “won”–become sustainable in perpetuity, or at least for a very long time. Success, rather, consists of staying in the game.
– Jospeh Tainter, author of The Collapse of Complex Societies, in a 2009 talk you can read here.
