“The metabolic requirements of a city can be defined as all the materials and commodities needed to sustain the city’s inhabitants at home, at work and at play. Over a period of time these requirements include even the construction materials needed to build and rebuild the city itself. The metabolic cycle is not completed until the wastes and residues of daily life have been removed and disposed with a minimum of nuisance and hazards.”

Abel Wolman, “The Metabolism of Cities,” 1965¹

“Circulation is as new and as fundamental an idea as gravitation, preservation of energy, evolution, or sexuality. But neither the radical newness of the idea of circulating “stuff” nor its impact on the constitution of modern space has been studied with the same attention that was given to Kepler’s laws or to the ideas of Newton, Helmholz, Darwin, or Freud.”

Ivan Illich, H₂O and the Waters of Forgetfulness, 1986²