Metabolism-First views the biosphere as a feature of Earth as a whole, a companion to the hydrosphere, lithosphere and atmosphere. Just as ordinary phase transitions change the properties of a liquid or gas, the biosphere can be viewed as emerging through a series of phase transitions operating on chemical reaction networks. A key concept of the theory is autocatalysis, the property of some chemicals to amplify their own rate of formation. Autocatalysis plays the same role in "chemical evolution" as Darwinian selection does in the standard theory of evolution. Additional key concepts include phase transformations, modularity and dissipative adaptation. The text includes a glossary and an annotated bibliography.