"Make hay while the sun shines."

We live in a world of unprecedented wealth, resulting from the harvesting of the enormous storages of fossil fuels created by the earth over billions of years. We have used some of this wealth to increase our harvest of the earth's renewable resources to an unsustainable degree. Most of the adverse impacts of this over-harvesting will show up, as available fossil fuels decline. In financial language, we have been living by consuming global capital in a reckless manner that would send any business bankrupt.

We need to learn how to save and reinvest most of the wealth that we are currently consuming or wasting so that our children and descendants might have a reasonable life. The ethical foundation for this principle could hardly be clearer. Unfortunately, conventional notions of value, capital, investment and wealth are not useful in this task.

Inappropriate concepts of wealth have led us to ignore opportunities to capture local flows of both renewable and non-renewable forms of energy. Identifying and acting on these opportunities can provide the energy by which we can rebuild capital, as well as provide us with an "income" for our immediate needs.

This principle deals with the capture and long-term storage of energy, that is, savings and investment to build natural and human capital. The generation of income (for immediate needs) is dealt with in Principle 3: Obtain a yield.

The icon of sunshine captured in a bottle suggests the preserving of seasonal surplus and a myriad of other traditional and novel ways to catch and store energy. It also reflects the basic lesson of biological science: that all life is directly or indirectly dependent on the solar energy captured by green plants.

The proverb "make hay while the sun shines" reminds us that we have limited to time to catch and store energy before seasonal or episodic abundance dissipates.