When I first started teaching sustainability in gardening, these two articles were the most profound thinking I had read on the subject at that time. I am grateful to have had these in my head for the past five or six years and I am happy to share them with you.
The following links give you the material I used for the last part of our first class. All of what I worked from was in the second link, but the first link provides an excellent introduction to the meatier second.
This first link, provides some background leading up to where we are today. This second link, Imagining a Better Garden gives you the meat and potatoes of what I was addressing.