The underlying premise of this book is as follows, taken from the first paragraph: "Every substance and raw material required for our existence comes from Earth's biosphere, and all depleted or discarded substances and materials are returned to the biosphere as waste to be assimilated and recycled by Earth's ecological systems. These materials and processes are literally our life support systems. They are also the foundation upon which all economic activity and every other human endeavor are based. Consequently, Earth's ability to provide these essential materials and to regulate these critical processes establishes the limit for all human enterprise." The book is an accessible scientific explanation and assessment of Earth's fundamental biogeochemical systems and natural resources. The book provides a detailed explanation of the functioning of the carbon, nitrogen, oxygen, water, methane, and phosphorus cycles, along with critical natural resources such as water, soil, rare earth minerals, phosphates, reactive nitrogen, and arable land. Along with the explanation of each cycle and resource, you will find a detailed explanation of how human activities are disrupting each of these ecological cycles and depleting and damaging these resources. Through the course of the book, the reader learns that linear economic growth, a wide assortment of injurious land-use practices, and population momentum are the primary global drivers that have led us to collectively exceed the biogeochemical boundaries of our Earth systems. The book closes with the principles of the steady-state economy of H.E. Daly, along with economic and natural resource accounting models that could provide the tools for quantifying and accounting for the environmental impacts of human enterprise. We are at a juncture in the history of our planet and our species where we must return to thinking about our economy and sustainability as fully interdependent factors and begin to measure our economic progress in ways that account for our environmental and social impacts. Now that we can measure, we can manage. The road to a healthier environment will be paved with a shared vision of a world where we recognize natural capital as valuable, or some some cases, more valuable, than economic capital and begin to treat it as such in the choices we make at every level of human enterprise.