Since the field's inception in the 1990s, ecocriticism has characterized eighteenth-century thinkers as imperialist and utilitarian. Treating romanticism as the dawn of an environmentalist re-enchantment of the world, ecocritics claimed that eighteenth-century writers saw nature as inert matter upon which to assert human mastery. Their critiques had some basis; many — perhaps most — eighteenth-century writers saw the use of nature for human benefit as both a necessity and a divine right. Yet as eighteenth-century scholars like Christopher Hitt, David Fairer and Sylvia Bowerbank have pointed out, eighteenth-century writers and texts expressed care and concern for the non-human world as often as they asserted mastery over it. In fact, simultaneously advocating anthropocentric utilitarianism and ecocentric care of nature is, as Hitt argues, characteristic of eighteenth-century writers. The challenge now is to recover the ecocentric aspects of eighteenth-century thought that were left out of early ecocritical accounts without glossing over the period's utilitarianism. My dissertation examines the ways eighteenth-century writers attempted to reconcile human beings' right to profit from nature with their responsibility to protect it. Because eighteenth-century thinkers saw use and care as complementary rather than contradictory goals, I argue that their attitude to nature is best described by the concept of 'usufruct.' A legal term for the 'right of temporary possession, use, or enjoyment of the advantages of property belonging to another, so far as may be had without causing damage or prejudice' (OED), usufruct explicitly combines the right to use nature for human benefit with the responsibility to steward it for future generations. Eighteenth-century writers, I show, were acutely aware of the interdependence of human and non-human beings, and believed that human beings had a responsibility to use nature in a way that would guarantee the ongoing stability of non-human and human life. Tracing the concept of usufruct in eighteenth-century literature reveals that the period's writers grappled more profoundly and consistently with the need to reconcile the often-contradictory ethical imperatives to improve human life and steward non-human life than has previously been appreciated by either ecocritics or eighteenth-century scholars.