Although the manuscript for the book was completed in 1993, the author did not have an opportunity to publish it before her death in 2001. Diana Wright of the Sustainability Institute saw the manuscript to publication in 2008. The work is a wonderful introduction to systems thinking, and many of the examples chosen to illustrate systems concepts relate directly to issues of sustainability. Meadows discusses the principles of systems, including: stocks, flows, and dynamic equilibrium; feedback loops; shifting dominance, delays, and oscillations; scenarios and testing models; constraints on systems; reliance, self-organization, and hierarchy; sources of system surprises; and mindsets and models. She points out system traps and how to avoid them, including: policy resistance; the tragedy of the commons; drift to low performance; escalation; success to the successful; shifting the burden to the intervenor; rule beating; and seeking the wrong goal. She lists the most effective leverage points at which we may intervene in systems from least to most effective: numbers; buffers; stock-and-flow structures; delays; balancing feedback loops; reinforcing feedback loops; information flows; rules; self-organization; goals; paradigms; and transcending paradigms. Finally, she provides guidelines for living in a world of systems that could be a moral code for living on Earth: 1. Get the beat of the system; 2. Expose your mental models to the light of day; 3. Honor, respect, and distribute information; 4. Use language with care and enrich it with systems concepts; 5. Pay attention to what is important, not just to what is quantifiable; 6. Make feedback policies for feedback systems; 7. Go for the good of the whole; 8. Listen to the wisdom of the system; Locate responsibility within the system; 10. Stay humble -- stay a learner; 11. Celebrate complexity; 12. Expand time horizons; 13. Defy the disciplines; 14. Expand the boundary of caring; and 15. Don't erode the goal of goodness. This is a book to be read more than once and thought about carefully.