Deliberately promotes a novel approach, by emphasising the physical concept of action, to complement that of energy. It shows that too much attention may have been devoted to energy in biothermodynamics and insufficient to action. This relative neglect may now be limiting our capacity to understand how ecosystems function, how they evolved and if they can be sustained as human demands for food and shelter increase. The idea that an appreciation of action will be needed in future to ensure a proper integration of physical, chemical and biological phenomena essential to safeguard and sustain the Earth's ecosystems is developed.