An ecologically sustainable society cannot be achieved without citizens who possess the virtues and values that will foster it, and who believe that individual actions can indeed make a difference. draws on ancient Greek thought—and Plato's in particular—to put forward a new vision of citizenship that can make such a society a reality. Melissa Lane develops a model of a society whose health and sustainability depend on all its citizens recognizing a shared standard of value and shaping their personal goals and habits accordingly. Bringing together the moral and political ideas of the ancients with the latest social and psychological theory, Lane illuminates the individual's vital role in social change, and articulates new ways of understanding what is harmful and what is valuable, what is a benefit and what is a cost, and what the relationship between public and private well-being ought to be. reveals why we must rethink our political imagination if we are to meet the challenges of climate change and other urgent environmental concerns. Offering a unique reflection on the ethics and politics of sustainability, the book goes beyond standard approaches to virtue ethics in philosophy and current debates about happiness in economics and psychology. explains why health is a better standard than happiness for capturing the important links between individual action and social good, and diagnoses the reasons why the ancient concept of virtue has been sorely neglected yet is more relevant today than ever.