What is sustainability?
In general we refer to sustainability in relation to nature or to the earths well being. Living a sustainable life means that we take from nature as much as it can regenerate, so that a the cycle of life can go on for ever. We also strive towards a local community that can provide all nutritional requirements, without sacrificing quality or depleting the land that produces it.
If we would log a tree to make a chair then this chair should last until nature has regrown a new tree. As a result, with this new grown tree, we can replace the chair when it has become unusable, this way we can go on for ever.