In a sustainable economy, all forms of capital will be conserved and we will live off the interest. In a green economy, biodiversity becomes part of the logic of production, and will be recognized as the ultimate source of all wealth. This is a significant departure from the conventional view, which sees environmental protection as primarily a task of meeting social expectations, and as a cost burden to minimize. This distinction is important because it opens up new possibilities. There are limits to quantitative growth.
Planet earth is a closed system and can only support a finite amount of activity.
Unless exponential economic growth eventually ceases, one or all of these limits will be crossed and human beings will struggle with each other and the natural world to protect their lives and livelihoods. There are mountains of evidence suggesting some limits may have already been crossed. The good news is there are no limits to development. We can always find ways to make life better, more beautiful, more just, more creative, more efficient and more fulfilling. Humans have an enormous capacity to learn, change and evolve.