What is Sustainability?

The first time I was really introduced to sustainability was in terms of fuels. In my first year seminar we learned about peak oil, the point at which global production of petroleum would reach its highest point and then begin to run out, making it increasingly more expensive until it was either drained completely or too expensive for most people to use. So in that context we talked mostly about what methods of creating fuels would sustainably be able to provide for the population. It sort of bled into a lot of other ideas about how industries that depend heavily on fossil fuels would change, with most of the focus on agriculture. So for a long time when some one talked about it, that was the idea that popped into my head right away.
A couple summers ago I saw a show about a family in Britain that decided to try and build a sustainable lifestyle, so they moved to an old farm and began to revamp it to supply all their needs for food, power and water on their own. They diverted a stream with an aqueduct to power a water wheel and generate electricity. They started a food garden and bought livestock. They built a water recycling system. It was very complicated. So I think where I’m going with this is that when i think of it now, I think more of being self sufficient and not wasting anything at all. And usually that self sufficiency is tied to having a farm. It’s not something you can really do all the way in a city.