ABSTRACT
The intrinsic barriers are grouped into three categories: barriers related to physical reality, barriers related to human condition, and barriers related to social reality. The first category is barriers related to the nature of our physical reality. The fundamental laws of nature confine our endeavours for sustainability. Complexity, for instance, is an inherent feature of many biological and ecological systems (and, of course, social systems as well). Another is related to energy – the energy return on energy invested.
