"You can't work on an empty stomach."

The previous principle focused our attention on the need to use existing wealth to make long-term investments in natural capital. But there is no point in attempting to plant a forest for the grandchildren if we haven't got enough to eat today.

This principle reminds us that we should design any system to provide for self-reliance at all levels (including ourselves) by using captured and stored energy effectively to maintain the system and capture more energy. More broadly, flexibility and creativity in finding new ways to obtain a yield will be critical in the transition from growth to descent.

Without immediate and truly useful yields, whatever we design and develop will tend to wither while elements that do generate immediate yield will proliferate. Whether we attribute it to nature, market forces or human greed, systems that most effectively obtain a yield, and use it most effectively to meet the needs of survival, tend to prevail over alternatives. A yield, profit or income functions as a reward that encourages, maintains and/or replicates the system that generated the yield. In this way, successful systems spread. In systems language, these rewards are called positive feedback loops that amplify the original process or signal. If we are serious about sustainable design solutions, then we must be aiming for rewards that encourage success, growth, and replication of those solutions.

The original permaculture vision promoted by Bill Mollison of growing gardens of food and useful plants rather than useless ornamentals is still an important example of the application of this principle. The icon of the vegetable with a bite taken shows the production of something that gives us an immediate yield but also reminds us of the other creatures who are attempting to obtain a yield from our efforts.