Richard Bawden

Sustain [v]: cause to be continued for an extended period or without interruption (OED) Ergo from a systems perspective, sustainability is the capability of any system, concrete or abstract, real or imagined, to keep on keeping on into the future. Such a system will need to be able to self-reproduce, self-organize, and keep being what it is, and doing what it does, as an integrated, bounded entity. It will have an inherent capacity for adaptability, enduring and remaining viable over time, even as it may evolve, and more especially co-evolve, with other systems in a manner where that dynamic process itself is sustainable. All of this will be accomplished through the functional, dynamic inter-connectedness of its nested component sub-systems and the environmental supra-system in which it is embedded itself as a sub-system of that higher order system.