As I found out in the first article of this series, sustainability is the balance allowing a population to fully express its potential without endangering the carrying capacity of its environment.
This balance results from the harmony between five forces interacting with each other: the material domain (natural resources), the economic domain (wealth), the domain of life (biodiversity), the social domain (culture), and the spiritual domain (ethics).
A sustainable project must address all five domains. To do that, Dr. Ben-Eli proposes five corresponding principles.
Material domain: the first principle derives from the fact that all physical processes abide by the first and second laws of thermodynamics. Growth is limited by the law of conservation of energy, so we need to use our natural resources as best as we can. Humans have the potential to act as agents of order that can contain entropy, so we also must do our best to increase the performance of our industrial processes.
Economic domain: the second principle proposes that our approach to economic growth is flawed and that we need to reinvent our conception of wealth to take into account all forms of capital (human, social, manufactured, financial, and natural), measures of human development, and nature's regeneration capacity.
Domain of life: "biosphere diversity has to be maintained", the gene pool of all living beings has to be conserved and diversified.
Social domain: social diversity is the catalyst of human knowledge. All humans should be given maximum freedom to blossom and self-realization opportunities, without anyone adversely affecting others.
Spiritual domain: all sustainable efforts have to take into account the fact that the human spirit seeks transcendence. Without this aspect, we can't be united by "a common purpose to provide a common foundation and stimulate common resolve".