Energy (earth) & Awareness (people). Energy is external, physical world, awareness is internal.
Energy is required to interface between systems; the energy cost of interaction increases the further apart systems are from each other in terms of storing energy and/or awareness.
Permaculture is a tool that increases our awareness so that we can capture and/or store more energy and cycle it through the system in a greater number more and efficient ways.
We have available a fixed energy budget based on the sunlight that hits the earth. There is also a limited supply of energy stored by life on earth.
Our ever growing awareness is the only thing that can increase.