Sustainability is not a Thing, but rather a Dynamic State - that is, only measurable in the Present Moment, or forecastable for the Future. 

“A Fully Sustainable State is achieved by managing the interaction of man with the natural environment in such a way that both can flourish”.

In practical terms, this means making choices about policies, programs, and projects that help, 

support, use, and/or mimic natural systems and processes – at similar scales (in 4 dimensions) – so that the 

vital support services they provide in turn to all life on the planet can function fully and 

efficiently. Sustainability suggests that we learn from nature how to deal with problems in 

ways which do not create more problems - addressing ROOT causes, not symptoms (which create more symptoms).