Re-defining the borders of the human may be the most important task for twenty-first-century environmentalism; and the high road to a posthuman culture-one that acknowledges our enmeshments and denies our exceptionalism-may circle back through the pre-modern. During the Renaissance, the boundaries of the individual person and the boundaries of the human species tended to rise and, more often, fall, in tandem. Shakespeare’s tragedies predominantly warn of the costs of a hubristic investment in the self and its insularity; the comedies depict the redemptive force of accepting one’s place in nature (and nature’s place within oneself); and the late career tragicomedies reconcile human aspirations with the functions of the biosphere.