“Cynics and Stoics” is an investigation into ecological aspects of both schools’ injunction that individuals should practice “self-sufficiency” (autarkeia) and live “according to Nature.” The relationship of autarky to the sustainability of systems on a global scale is considered in light of Cynic and Stoic cosmopolitanism and virtue ethics. The relationship of subsistence to sustainability is illuminated by Cynic practice and grounded in the modern concept of “appropriate technology.” The Stoic doctrine of oikeiōsis (“proprioception”) is presented as an early instance of an “environmental ethics” that still speaks to the manifold relationships that human beings have to one another and that our species has to the rest of the natural world.